TeV Particle Astrophysics 2011

Aug 1, 2011, 8:00 AM → Aug 5, 2011, 6:30 PM Europe/Stockholm

AlbaNova University Center

Thanks to all participants for coming to TeVPA!

The fields of high energy astrophysics, particle astrophysics and particle physics at colliders are dealing with some of the most pressing subjects in modern physics, like

• What is the nature of dark matter?
• What is the origin of cosmic rays?
• How do cosmic accelerators work?

The complexity of the above mentioned questions makes it necessary to interprete the whole suite of experimentally available data consistently. TeVPA 2011 will provide this opportunity as a place where the consistency of experimental results can be checked and possible interpretations can be discussed among both experimentalists and theorists.

Format

The format will be plenary invited talks before lunch and invited and contributed talks in parallel sessions after lunch. The invited speakers, with tentative titles, are:

• AMS, Stefan Schael
• Latest PAMELA results, Mirko Boezio
• Air Cherenkov Telescope overview, Jim Buckley
• Recent results from the LHC, David Berge
• Recent results from neutrino telescopes, Ignacio Taboada
• Recent results from Fermi, Seth Digel
• Direct detection of dark matter, Paolo Gondolo
• Recent results from AUGER, Lorenzo Perrone
• Overview of recent results from ultra-high energy gamma ray experiments, Gus Sinnis
• Cosmic ray acceleration and sources, Pasquale Blasi
• Distribution of dark matter (observations and simulations), Justin Read
• Dark matter in light of recent cosmic ray data , Fiorenza Donato

Parallel sessions
There are seven parallel sessions at TeVPA running in the afternoons:

• Gamma rays. Conveners: Seth Digel, Christian Stegmann and Gabrijela Zaharijas.
• Neutrinos. Conveners: Tom Gaisser and Dan Hooper.
• Charged cosmic rays. Conveners: Mirko Boezio and Fiorenza Donato.
• Cosmic rays above the knee. Conveners: Michael Kachelriess and Esteban Roulet.
• Direct dark matter searches. Conveners: Paolo Gondolo and Neil Spooner.
• Distribution of dark matter. Conveners: Andrea Maccio and Justin Read.
• Particle physics. Convener: Kerstin Jon-And.

Local organising committee

• Lars Bergström (Stockholm University)
• Jan Conrad (Stockholm University)
• Alessandro Cuoco (Stockholm University)
• Hugh Dickinson (Stockholm University)
• Joakim Edsjö (Stockholm University)
• Chad Finley (Stockholm University)
• Klas Hultqvist (Stockholm University)
• Miranda Jackson (Royal Institute of Technology)
• Maja Llena-Garde (Stockholm University)
• Elena Moretti (Royal Institute of Technology)
• Tanja Nymark (Royal Institute of Technology)
• Mark Pearce (Royal Institute of Technology)
• Antje Putze (Stockholm University)
• Joachim Ripken (Stockholm University)
• Felix Ryde (Royal Institute of Technology)
• Christopher Savage (Stockholm University)
• Stephan Zimmer (Stockholm University)

Scientific organising committee

• Felix Aharonian (DIAS Dublin & MPIK Heidelberg)
• Laura Baudis (U. of Zurich)
• John Beacom (Ohio State U.)
• Gianfranco Bertone (IAP Paris & ITP Zurich) - chair
• Elliott Bloom (KIPAC-SLAC)
• Jonathan Feng (UC Irvine)
• Gian Francesco Giudice (CERN)
• Francis Halzen (U. of Wisconsin, Madison)
• Dan Hooper (Fermilab)
• * Konstantin Matchev (U. of Florida)
• Olga Mena (U. "La Sapienza", Rome)
• Igor Moskalenko (KIPAC - Stanford U.)
• Xinmin Zhang (IHEP Beijing)

The TeVPA 2011 Conference has received support from the Nobel Committee for Physics at the Royal Academy of Sciences and from the Swedish Research Council.

document tevpa2011-info-conf-dinner.pdf

Monday, August 1

Registration

Registration for the conference

Plenary talks

1 Welcome address

Speaker: Prof. Gianfranco Bertone (ITP Zurich)

Slides Bertone-tevpa2011.pdf

2 Introductory remarks

Speaker: Prof. Joakim Edsjö (Oskar Klein Centre / Stockholm University)

Slides Edsjo-Welcome-talk.pdf

9:50 AM Coffee break

Plenary talks

3 Status of the AMS-02 Experiment on the ISS

The Alpha Magnetic Spectrometer (AMS) is a high precision general-purpose particle physics detector that has been constructed in the past twelve years by a group of 600 scientists and engineers from 16 countries for the operation on board of the International Space Station (ISS). NASA and its international partners decided in 2010 that the ISS will be operated at least until 2020 with a possible extension till 2028. To use this new opportunity and to widen the scientific program of AMS, the originally proposed superconductive magnet was replaced by a permanent magnet. In order to guarantee the same detector resolution at a reduced magnetic field the lever arm of the silicon tracker of AMS-02 was increased. The new detector configuration was calibrated in a test beam at CERN in August 2010 and delivered to Kennedy Space Center in September 2010. In May 2011 AMS-02 was launched with the last flight of the Space Shuttle Endeavour and installed on the ISS. Since the first day AMS-02 is fully operational and delivers high quality measurements of cosmic rays with a precision and a statistical volume never reached before. The status of the experiment and the perspectives for the coming years will be presented.

Speaker: Prof. Stefan Schael (RWTH Aachen University)

Slides AMS_Schael_TevPA2011_v01.pptx.pdf

4 Cosmic-ray measurements with the PAMELA space-borne experiment

The PAMELA satellite-borne experiment has presented new results on the composition of the charged cosmic radiation that challenge the current paradigm of cosmic-ray acceleration and propagation in the Galaxy. The instrument was launched from the Baikonur cosmodrome and it has been collecting data since July 2006. The combination of a permanent magnet silicon strip spectrometer and a silicon-tungsten imaging calorimeter allows precision studies of the charged cosmic rays to be conducted over a wide energy range with high statistics. The primary scientific goal is the measurement of the antiproton and positron energy spectrum in order to search for exotic sources. PAMELA is also searching for primordial antinuclei (anti-helium), and testing acceleration and propagation models through precise measurements of the cosmic-ray energy spectrum and precision studies of light nuclei and their isotopes. This talk illustrates the most recent scientific results obtained by the PAMELA experiment.

Speaker: Dr Mirko Boezio (INFN Sezione di Trieste)

Slides TeVPA2011_MBoezio.pdf

12:00 PM Lunch break

Charged cosmic rays - astrophysics and dark matter

Charged cosmic rays - astrophysics and dark matter

5 The Three Flights of ATIC: Summary of Results

The Advanced Thin Ionization Calorimeter (ATIC) balloon experiment traveled to McMurdo, Antarctica four times, resulting in three successful circumpolar flights: ATIC-1, a test flight; ATIC-2, a science flight; ATIC-3, a balloon failure; ATIC-4, the final science flight. In particular, ATIC-4 provided the data to understand the discrepancy between the H, He spectra reported from ATIC-1 and 2 (the ATIC-1 results are withdrawn) and allowed an increase in calorimeter depth by 25%, thereby yielding improved measurements of the cosmic ray electron spectrum. ATIC results revealed the hardening in the very high energy H and He spectra, provided new measurements of the spectra of the major heavy nuclei and demonstrated the existence of an excess of cosmic ray electrons in the sub-TeV energy range. The ATIC flights and the ATIC science results are discussed in the context of other recent measurements and astrophysical models.

Speaker: Prof. John Wefel (Louisiana State University)

Slides Wefel-TeV-PA-Sweden.pdf

6 Fermi-LAT measurement of Cosmic-Ray positron spectrum using the Earth's magnetic field

With a precise measurement of the combined Cosmic-Ray electron and positron spectrum, the Fermi Large Area Telescope (LAT) has proven to be an excellent electron detector. Being a purely calorimetric experiment, the LAT is not capable to directly distinguish particle charge. However, we can exploit the Earth's magnetic field to effectively separate negatively and positively charged particles. With the aid of a precise tabulation of the geomagnetic field, we are able to predict trajectories of particles in this field and use this information to discriminate between positrons and electrons. In this talk we present the details of this analysis together with the preliminary results on the positron and electron spectra for energies greater than 20 GeV. The derived positron fraction will be also discussed.

Speaker: Dr Carmelo Sgro' (INFN-Pisa)

Slides carmelo_tevpa2011_positrons.pdf

7 PAMELA: Electrons and Positron Spectra Measurement in the Cosmic Rays

PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays in a wide energy range. The study of the antimatter component is one of the PAMELA main objectives. The lepton component of cosmic radiation has been measured by PAMELA in a wide energy range with unprecedent sensitivity. The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June 15th 2006 in a 350 - 600 km orbit with an inclination of 70 degrees. The measurement of galactic electron and positron spectra in the energy range between 1 GeV and few hundred GeV will be presented.

Speaker: Dr Emiliano Mocchiutti (INFN (Istituto Nazionale di Fisica Nucleare) Trieste)

Slides Mocchiutti_PAMELA_electrons_and_positrons_-_WEB.pdf

Ultra high energy cosmic rays - above the knee

8 High-energy cosmic rays measured with KASCADE-Grande

The detection of high-energy cosmic rays above a few hundred TeV is realized by the observation of extensive air-showers. By using the multi-detector setup of KASCADE-Grande the energy spectrum, elemental composition, and anisotropies of high-energy cosmic rays in the energy range from below the knee up to 1 EeV are investigated. The most distinct feature of the spectrum, the ‘knee’, is thought to be the beginning of the end of the galactic origin of cosmic rays. As the highest energies (above the ‘ankle’) are most probably of extragalactic origin, between 10 PeV to 1 EeV one expects the transition of galactic to extragalactic origin. KASCADE-Grande is dedicated to explore this transition region. The estimation of energy and mass of the high-energy primary particles is based on the combined investigation of the charged particle, the electron, and the muon components measured by the detector arrays of Grande and KASCADE. Recent results from the KASCADE-Grande experiment will be shown and compared with results from other experiments, and their astrophysical implications discussed.

Speaker: Dr Andreas Haungs (Karlsruhe Institute of Technology)

Slides Haungs-TeVPA.pdf

9 Results from the Telescope Array Experiment

The Telescope Array (TA) Experiment is the largest experiment studying ultrahigh energy cosmic rays in the northern hemisphere. TA is a hybrid experiment, which means it consists of a large surface array of scintillation counters plus three fluorescence detectors overlooking the surface array. TA has been collecting data for about three years. Measurements of the spectrum and composition of cosmic rays between about 1 and 100 EeV will be presented, and searches for anisotropy in their arrival directions will be described.

Speaker: Dr Hiroyuki Sagawa (ICRR, University of Tokyo)

Slides TA-sagawa-TEVPA.pdf

10 Mass composition studies and photon fraction limits of UHECR with the Pierre Auger Observatory

Due to its hybrid design, the Pierre Auger Observatory provides a variety of independent experimental observables for the study of the composition of ultra-high energy cosmic rays. Ground level measurements from the surface detector allow to define composition sensitive parameters while the fluorescence detector provide a direct observation of the depth of maximum development of the longitudinal profile of air showers. A comparison of the results obtained with both techniques will be presented. Furthermore, these composition sensitive observables combined with the large collection area of the Observatory, also provide an excellent opportunity to search for photons within the hadronic background. These photons are expected to be produced, for example, from the decay of neutral pions in the standard GZK process or in exotic scenarios such as "top-down" models. Upper limits on the fraction of photons above 1 EeV that place severe constraints on "top-down" models will be also presented.

Speaker: Maria Monasor Monasor (University of Chicago)

Slides MonasorTeVPA.pdf

3:30 PM Coffee break

Charged cosmic rays - astrophysics and dark matter

Charged cosmic rays - astrophysics and dark matter

11 GAPS: An Indirect-Detection Dark Matter Search Experiment

The General Antiparticle Spectrometer (GAPS) experiment is a balloon-borne instrument designed to detect low-energy (< 0.5 GeV/n) anti-deuterons, which could be a signature for dark matter annihilation. In the energy region probed by GAPS, very little anti-deuteron background is expected from conventional astrophysical sources and hence the detection by GAPS of even a few anti-deuterons would be very significant. GAPS will consist of a large Si(Li) tracker, surrounded on the top and sides by a time-of-flight system, that also serves as an anti-coincidence shield. Anti-deuterons are detected by an exotic atom technique which produces characteristic X-rays and pion tracks in the Si(Li) detector. The current status of GAPS will be reviewed with emphasis placed on the development of a prototype detector (pGAPS), scheduled for flight in 2011.

Speaker: Rene Ong (LLR-Ecole Polytechnique/UCLA)

Slides TeVPA2011-GAPS-Ong.pdf

12 Cosmic Ray Anisotropy at TeV energies with ARGO-YBJ

The ARGO-YBJ experiment, located at the Yangbajing Cosmic Ray Laboratory (Tibet, 4300 m asl, 606 g/cm2), is an EAS-array exploiting the full coverage approach at high altitude. We analyzed the data taken since November 2007 looking for anisotropies in the arrival directions of cosmic rays on different angular scales. The results of the analysis are reported and compared with other experiments.

Speaker: Dr Giuseppe Di Sciascio (INFN - Sezione di Roma Tor Vergata)

Slides DiSciascio-TeVPA11-Anisot-OK.pdf

13 The search for TeV cosmic ray electrons with the CREST experiment

The Cosmic Ray Electron Synchrotron Telescope (CREST) high-altitude balloon experiment is a pathfinding effort to detect multi-TeV cosmic-ray electrons. These electrons would be indicative of nearby cosmic accelerators, since energetic electrons from distant Galactic sources are depleted by radiative losses during interstellar transport. The electrons will be detected indirectly by the characteristic signature of their geomagnetic synchrotron losses: a group of collinear x-ray photons intersecting the instrument. Since the primary electron itself need not traverse the payload, an effective detection area is achieved that is several times the nominal 6.4 m^2 instrument. The payload is composed of an array of 1024 BaF2 crystals surrounded by a set of plastic scintillator detectors which veto through-going charged particles. A long-duration balloon flight in Antarctica is planned for the upcoming 2010-11 season.

Speaker: Prof. Scott Nutter (Northern Kentucky University)

Slides Nutter-TeVPA2011-CREST-upload.pdf

14 Measurement of the Hydrogen and Helium absolute fluxes with the PAMELA experiment

The PAMELA experiment has recently reported results on the absolute fluxes of hydrogen and helium nuclei. The high-precision measurement performed by the experiment revealed for the first time interesting spectral features, which are presently at the centre of a lively debate. In this presentation the results will be discussed focusing on the experimental issues related to the measurement.

Speaker: Dr Elena Vannuccini (INFN - Firenze)

Slides PAMELA-HHe-Vannuccini-TeVPA.pdf

15 Measurement of Cosmic Ray antiproton/proton flux ratio at TeV energies with ARGO-YBJ

Cosmic ray antiprotons provide an important probe for the study of cosmic-ray propagation in the interstellar space and to investigate the existence of Galactic dark matter. The ARGO-YBJ experiment, located at the Yangbajing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm$^2$ ), is the only experiment exploiting the full coverage approach at very high altitude presently at work. The ARGO-YBJ experiment is particularly effective in measuring the cosmic ray antimatter content via the observation of the cosmic rays Moon shadowing effect. Based on all the data recorded during the period from July 2006 through November 2009 and a full Monte Carlo simulation, we searched for the existence of the shadow produced by antiprotons at the few-TeV energy region. No evidence of the existence of antiprotons was found in this energy region. Upper limits to the antip/p flux ratio are set to 5% at a median energy of 2 TeV and 6% at 5 TeV with a confidence level of 90%. In the few-TeV energy range this result is the lowest available.

Speaker: Dr Giuseppe Di Sciascio (INFN - Sezione di Roma Tor Vergata)

Slides DiSciascio-TeVPA11-Antip-OK.pdf

Ultra high energy cosmic rays - above the knee

16 The first result of the CERN LHCf experiment

LHCf is an experiment at CERN LHC and is dedicated to measure photons and neutrons in the very forward region to calibrate M.C event generator. Cosmic ray research over 10^14 eV normally uses air shower observation technique which must employ M.C simulation to derive incident cosmic ray energy and species etc. Air shower development is governed by the energetic secondary particles but we have meager information about the spectra of such particles. Therefore, we must calibrate M.C codes by experimental data. The first LHCf data on the photon spectrum is compared with M.C used in the cosmic ray field. The interaction model validity will also be discussed in conjunction with other LHC data on the eta distribution in the central region.

Speaker: Prof. katsuaki kasahara (waseda university)

Slides kasaharaStockholm.pdf

17 High energy CR composition, interaction models, and LHC data

The present status of high energy cosmic ray composition studies is discussed. In particular, the issue of the model-dependence of experimental results is addressed. The impact of recent LHC measurements on the interpretation of cosmic ray data is investigated.

Speaker: Dr Sergey Ostapchenko (Norwegian University for Science and Technology (NTNU))

Slides tevpa_models_ostapch.pdf

18 Anisotropy studies at the Pierre Auger Observatory

I will review the recent results of the Pierre Auger Observatory on the arrival directions of ultrahigh-energy cosmic rays . I will present the latest salient results of the Pierre Auger Observatory, namely the current level of correlation between arrival directions of ultrahigh-energy air showers and the direction of nearby active galactic nuclei, the diffuse excess of events in the region of the radiogalaxy Centaurus A, as well as the intrinsic anisotropy seen in the ultrahigh-energy sky. At lower energy, I will mainly focus on the search for galactic neutron point sources. Finally I will attempt to discuss these previous studies in the context of the cosmic- ray spectrum and composition estimated with the Pierre Auger Observatory data.

Speaker: Mr Denis Allard (APC)

Slides TeVPA-denis.pdf

19 Cosmic Rays in IceCube

IceCube is composed of the surface array IceTop and the volume detector InIce/DeepCore. This offers unique opportunities for cosmic-ray physics. One major objective is the measurement of cosmic-ray composition around and above the knee by correlating the electromagnetic content of air showers to the high-energy muon yield. Presented are first results from the surface array and from analyses using cosmic-ray muons in the in-ice detector. Cosmic ray primary spectrum and composition were measured from the knee to the 100 PeV region using combined surface and deep detector data. Independently, the InIce array alone can be used to constrain primary flux models and investigate the behavior of the proton flux around the knee. Using high-energy bremsstrahlung cascades along muon tracks, the cosmic ray-induced muon energy spectrum can be measured up to hundreds of TeV.

Speaker: Mr Patrick Berghaus (Bartol Research Institute, University of Delaware)

Slides icecube_cr_pb.pdf

20 GRBs and the UHECR connection

I will review the arguments on which a GRB origin of UHECR are based, including hypernovae-related models. I will discuss recent calculations as well as mention counterarguments and possible constraints.

Speaker: Prof. Peter Mészáros (Pennsylvania State University)

Slides meszaros-sto-cr11.pdf

21 Ultrahigh energy heavy nuclei from newly-born magnetars

Newly-born magnetars are good candidates for the acceleration of ultrahigh energy cosmic rays (Blasi et al. 00, Arons 03). We discuss issues related to the production of ultrahigh energy heavy nuclei in newly-born magnetars, in light of the latest results of the Auger Observatory.  Magnetars offer favorable sites for the injection of heavy nuclei (by stripping from the star surface or by r-process in the wind), and for their further acceleration to the highest energies by unipolar induction. Once accelerated in the wind, nuclei have to escape from the dense supernova envelope surrounding the magnetar. We examine this escape analytically and numerically.  We find that iron nuclei can escape from the envelope for a certain range of magnetar parameters, while protons and light elements never can. Iron escape leads to a transition from light to heavy nuclei from low to high energy as observed in the Auger data (Abraham et al. 2010), due to the production of secondary nucleons. Heavy nuclei escape from the envelope also results in a much softer spectral slope than the original injected power-law in -1, and, after propagation in the intergalactic medium, allows a good fit the observed ultrahigh energy cosmic ray spectrum.  In conclusion, we find that the injection of iron nuclei in magnetars within a certain range of parameters gives a picture that is surprisingly consistent with the UHECR overall data measured with Auger.

Speaker: Dr Kumiko Kotera (University of Chicago)

Slides kotera_11_08_01_TeVPA-web.pdf

22 Effects of Lorentz Invariance Violation in Ultra High Energy Cosmic Ray Physics

After a general overview we discuss constraints on the size of Lorentz symmetry breaking terms resulting from comparing measured ultra-high energy cosmic ray spectra with theoretical predictions in the presence of Planck scale suppressed Lorentz Invariance Violation (LIV). Finally, we will discuss how LIV tests could become more sensitive in the future due to the anticipated progress in UHECR observations, with particular focus on how a better understanding of chemical composition could be exploited.

Speaker: Andrey Saveliev (University of Hamburg)

Slides Saveliev_TeVPA2011.pdf

23 Sources and signatures of heavy nuclei UHECR

Recent results from the Pierre Auger Observatory show that the composition of ultra-high energy cosmic rays (UHECR) becomes increasingly heavier on average with energy. We discuss potential sources of UHECR in light of these results. In particular, we detail on how some models of GRBs naturally predict UHECRs that can even be dominate by very heavy nuclei beyond iron. We also discuss potential signatures of nuclei UHECR.

Speaker: Dr Shunsaku Horiuchi (CCAPP, Ohio State University)

Slides TeVPA2011horiuchi.pdf

7:30 PM Welcome Reception

Tuesday, August 2

Plenary talks

Convener: Prof. Per-Olof Hulth (Stockholm University)

24 Dark matter in light of recent cosmic ray data

I will review the interpretation of the most recent data on cosmic antimatter in terms of a possible Particle Dark Matter contribution. A major attention will be paid to the production of positrons and antiprotons by astrophysical sources, acting as a background in the indirect Dark Matter searches. The particle candidates confronted with the most recent antimatter data will be discussed. Perspectives for the searches with antideuterons will be touched.

Speaker: Dr Fiorenza Donato (Torino University)

Slides Donato.ppt

9:50 AM Coffee break

Plenary talks

Convener: Prof. Per-Olof Hulth (Stockholm University)

25 Ultra-High Energy Cosmic Rays with the Pierre Auger Observatory

The Pierre Auger Observatory has been designed to investigate the origin and the nature of Ultra High Energy Cosmic Rays using a hybrid detection technique. It is located on a plateau in the Province of Mendoza, Argentina, and it consists of a surface array of about 3000 km^2 overlooked by 24 air fluorescence telescopes grouped in 4 sites, which together provide a powerful instrument for air shower reconstruction. The combination of information from the surface array, measuring the lateral distributions of secondary particles at the ground, and the fluorescence telescopes, observing the longitudinal profile, enhances the reconstruction capability with respect to the individual detector components. The Observatory was completed in 2008 and it is taking data smoothly since 2004. Moreover, detector enhancements are being constructed to extend the sensitivity of the Observatory towards the lower energies. A review of selected results is presented with the emphasis given to the measurement of energy spectrum, arrival directions, chemical composition and search for photons and neutrinos as primary particles.

Speaker: Dr Lorenzo Perrone (University of Salento and INFN Sezione di Lecce (Italy))

Slides TevPa_talk_upload.pdf

26 High-energy astrophysics with Neutrino Telescopes

We will review the status and results of future and current neutrino telescopes. We discuss methods for data analysis and signal to background discrimination. The search for potential sources of galactic and extragalactic cosmic rays with neutrino telescopes is discussed. Emphasis is placed on the results of IceCube, a on gigaton neutrino telescope in operation at the South Pole.

Speaker: Ignacio Taboada (Georgia Institute of Technology)

Slides TeVPA_Neutrinos-web.pdf

12:00 PM Lunch break

Charged cosmic rays - astrophysics and dark matter

Charged cosmic rays - astrophysics and dark matter

27 The USINE cosmic-ray propagation code and recent results from an MCMC analysis

We implemented a Markov Chain Monte Carlo technique to estimate the probability-density functions of the cosmic-ray transport and source parameters in a diffusion model. From the measurement of the B/C ratio and radioactive cosmic-ray clocks, we calculate their probability density functions, with a special emphasis on the halo size L of the Galaxy and the local underdense bubble of size r_h. We also derive the mean, best-fit model parameters and 68% confidence level for the various parameters, and the envelopes of other quantities. Finally, we check the compatibility of the primary fluxes with the transport parameters derived from the B/C analysis and then derive the source parameters (slope, abundance, and low-energy shape). We conclude that the size of the diffusive halo depends on the presence/absence of the local underdensity damping effect on radioactive nuclei. Models based on fitting B/C are compatible with primary fluxes. The different spectral indices for the propagated primary fluxes up to a few TeV/n can be naturally ascribed to transport effects only, implying universality of elemental source spectra. The analysis relies on the public USINE package which deals with the propagation of Galactic cosmic-ray nuclei (all existing nuclei) and antinuclei (antiprotons and antideuterons) in various models (Leaky-Box and diffusion models).

Speaker: Dr Antje Putze (Oskar Klein Center (Stockholm University))

Slides TEVPA11_Putze.pdf

28 Radio data and synchrotron emission in consistent cosmic ray models

It is well established that even very simple phenomenological two-zone diffusion models of the galactic halo can reproduce cosmic-ray nuclear data, and the observed antiproton flux, surprisingly well. Here, we consider lepton propagation in such models and compute the expected galactic population of electrons, as well as the diffuse synchrotron emission that results from their interaction with galactic magnetic fields. We find models that are consistent not only with cosmic ray data but also with radio surveys at essentially all frequencies. Requiring such a globally consistent description of seemingly unrelated galactic phenomena strongly disfavors both very large (L > 15 kpc) and small (L<= 1 kpc) values for the effective size of the diffusive halo. This has profound implications for, e.g., indirect dark matter searches.

Speaker: Dr Torsten Bringmann (University Hamburg)

Slides TeVPA2011_Bringmann-web.pdf

29 On the SNR contribution to the spectra of secondary nuclei

We calculate the production and re-acceleration of secondary nuclei in supernova remnants using a time-dependent treatment of the acceleration process. The obtained spectra are compared to results of other recent calculations. The predictions for the energy-dependence of B/C and Ti/Fe ratios are presented and the implications for cosmic ray propagation models are discussed.

Speaker: Dr Sergey Ostapchenko (Norwegian University for Science and Technology (NTNU))

Slides snr-ostapchenko-web.pdf

Neutrinos - astrophysics and dark matter

30 UHE neutrinos from GRB and related sources

I will discuss the model dependence of the neutrino flux in the GeV to EeV range implied in the common GRB paradigm, in the light of recent IceCube constraints. Possible differences in the neutrino spectra expected in some recent variations on the GRB model will also be reviewed.

Speaker: Prof. Peter Meszaros (Pennsylvania State University)

Slides meszaros-sto-nu11.pdf

31 Search for neutrino sources with the IceCube Neutrino Observatory.

The IceCube Neutrino Observatory is a kilometer-scale detector located in the South Pole. The full detector comprises 5,160 photomultipliers (PMTs) deployed along 86 strings from 1.5-2.5 km deep in the ice. The detector construction finished during the Austral summer of 2010-11. In addition, a dense sub-array of 6 strings in the center of the detector together with 7 surrounding IceCube strings form DeepCore, which increases sensitivity to low energy neutrinos (< 100 GeV). Muon tracks arriving in the detector from neutrino interactions are reconstructed using the time and charge information detected by the array of PMTs. One of the main scientific goals of the IceCube experiment is the detection of astrophysical neutrinos that will help to understand and settle the unresolved questions about the origin and nature of cosmic rays. In this contribution we present the results of time-integrated and time-dependent searches for astrophysical neutrino sources performed over the whole sky using data collected between April 2008 and May 2010 with the 40-string and 59-string configurations of the IceCube Neutrino Observatory. An unbinned maximum likelihood ratio method is used to search for astrophysical signals, and for the first time adapted to combine data from multiple different detector configurations. The combined integrated sensitivity of the search is about a factor ~2.5 better than the previous 1 year limit of the 40-string configuration alone. Apart from the all sky survey we perform a dedicated search based on a catalog of sources, as well as a search based on flares of AGNs observed by other experiments, using lightcurve information from bands where comprehensive coverage is available. Stacking searches for selected source catalogs including extended sources are also presented.

Speaker: Juan Antonio Aguilar Sánchez (UW-Madison)

Slides tevpa2011-aguilar.pdf

32 Status of the ANTARES Neutrino Telescope

Neutrino astronomy plays a major role in the understanding of cosmic particle acceleration mechanisms and so may provide valuable information about the properties of the sources of the highest energy particles in the Universe. Another promising area of research of a neutrino telescope lies in the indirect search for dark matter particles or particles beyond the Standard Model. ANTARES, the largest neutrino telescope in the Northern hemisphere, is located in the Mediterranean Sea at a depth of 2475m. The telescope consists of an array of 885 light sensors along twelve vertical lines to detect the Cherenkov light from neutrino-induced muons. With the first line connected in 2006, observations in full mode started in May 2008. The recent status of observations and physics results will be presented and detection prospects will be discussed.

Speaker: Dr Stephanie Escoffier (Centre de Physique des Particules de Marseille)

Slides TeVPA2011_antares.ppt

33 Search for point sources with the ANTARES neutrino telescope

The ANTARES detector is the first full operational and the largest underwater neutrino telescope in the Northern Hemisphere. Located at 40 km offshore the coast of Toulon, it consists of 12 detection lines anchored to the seabed at a depth of 2475 m and divided on 25 foors (or storeys) composed by a triplet of photomultiplier tubes (PMTs). This three-dimensional photo-detector array detects the Cherenkov radiation induced by the charged particles originated in the interaction of high energy neutrinos with the matter surrounding the detector. From timing and position information of the hits arriving to the PMTs the track of the produced muon is reconstructed using a likelihood-based algorithm. The main goal of the experiment is the detection and identification of astrophysical sources of neutrinos. In this contribution results from the search for point sources analysis will be presented, including some of the most stringent limits for the Southern Sky.

Speaker: Mr Gómez González Juan Pablo (ANTARES)

Slides TeVPa_2011_PS_JPGomez.pdf

3:30 PM Coffee break

Charged cosmic rays - astrophysics and dark matter

Charged cosmic rays - astrophysics and dark matter

34 Constraints on cosmic-ray propagation and acceleration models from recent data

We are studying the constraints obtained on transport and acceleration mechanisms of galactic cosmic rays by using statistical tools, such as genetic algorithms or multimodal nested sampling algorithms, linked with the propagation package GALPROP and recent PAMELA data. Using only PAMELA data allows us to avoid inconsistencies between data sets from different experiments, minimize uncertainties on the solar modulation parameters, and have a complementary and precise data set on (anti-)matter as well as primary and secondary nuclei over 3 orders of magnitude in energy. This allows us to simultaneously place strong constraints on cosmic-ray propagation and acceleration models. Preliminary results will be presented and discussed.

Speaker: Ms Juan Wu (KTH and Oskar Klein Centre)

Slides CRTeVPA_Wu2.pdf

35 Constraints from electroweak bremsstrahlung and prospects for gamma ray detection

It is well known that the annihilation of Majorana dark matter particles into light leptons can be significantly enhanced by electromagnetic bremsstrahlung processes, which give rise to potentially observable signal in gamma-rays. Due to the gauge invariance, this mechanism inevitably leads to electroweak bremsstrahlung processes, which in turn lead to the production of antiprotons even when the leading order hadronic annihilation channels are forbidden. We investigate the constraints on the electroweak bremsstrahlung processes from the present measurements of the antiproton-to-proton fraction and we discuss the prospects to observe a gamma-signal in view of the antiproton constraints.

Speaker: Mr Stefan Vogl (Technische Universitaet Muenchen)

Slides Stefan_Vogl_TeV_PA_2011_Stockholm.pdf

Neutrinos - astrophysics and dark matter

36 Dark matter searches with IceCube

The construction of the IceCube neutrino observatory was completed in December 2010 and the detector is now operating with 86 strings and 5160 optical modules. The detector has been taking data in different configurations while construction took place. We present recent results from the searches for dark matter candidates with IceCube using the Sun and the Galactic Center and Halo as possible dark matter sources. Prospects for the complete detector are discussed, with emphasis on the possibilities presented by the dense DeepCore array to lower the sensitivity to neutrino energies in the 10 GeV region.

Speaker: Carlos de los Heros (Uppsala University)

Slides delosheros_tevpa11.pdf

37 Direct supersymmetric analyses with IceCube

Typical analyses of neutrino telescope data for signals of WIMP annihilation in the Sun assume some particular annihilation final states. Upper limits are drawn on WIMP-nucleon scattering cross-sections as a function of the WIMP mass, which must then be interpreted in terms of specific particle theories such as supersymmetry. This interpretation is often complicated by the question of equilibrium between capture and annihilation in the Sun, the broad range of annihilation final states in many models, and the resulting neutrino energy spectrum. I will describe a formalism for quickly and directly comparing event-level IceCube data with arbitrary annihilation spectra in detailed model scans, considering not only total event counts, but also event directions and energy estimators. I will show an application of this formalism to both model exclusion and parameter estimation in models of supersymmetry, including preliminary results with 22-string data, and projections for future constraints with 86-string data.

Speaker: Pat Scott (McGill University)

Slides http://www.physics.mcgill.ca/~patscott/talks/PS_TeVPA2011.pdf

38 Search for dark matter with the ANTARES neutrino telescope

The ANTARES neutrino telescope was completed in 2008 after the installation of its twelfth line. Its scientific scope is very broad, but the two main goals are the observation of astrophysical neutrino sources and the indirect detection of dark matter. The latter is possible through the detection of neutrinos produced after the annihilation of WIMPs, which would accumulate in sources like the Sun, the Earth or the Galactic Centre. The neutralino, which arises in Supersymmetry models, is one of the most popular WIMP candidates. Kaluza-Klein particles, which appear in Universal Extra Dimension models, form another one. Although in most models neutrinos would not directly be produced in these annihilations, they are expected from the decay of secondary particles. An important advantage of neutrino telescopes in general with respect to other indirect searches (like the detection of gamma rays) is that a potential signal (for instance from the Sun) would be very clean, since no other astrophysical explanations (like pulsars) could mimic it. A specific advantage of ANTARES is its location in the Northern Hemisphere, which allows for detection of neutrinos from the Galactic Centre. In this talk I will present the results of the ANTARES telescope for dark matter searches, which include neutralino and KK particles.

Speaker: Dr Juan de Dios Zornoza (IFIC)

Slides EstocolmoTeVPA-aug11_dm.pptx

39 On the cosmogenic neutrino flux

Cosmogenic neutrinos with energy up to ~10^{11} GeV originate from photo- hadronic interactions of UHECR protons with the CMB and the accompanying EM cascades generate a diffuse gamma-ray background in the GeV-TeV region. Thus Fermi-LAT measurements of the extragalactic gamma-ray flux constrain the cosmogenic flux and, indirectly, the UHECR source spectrum and its cosmological evolution in conjunction with air shower data from Auger and HiRes. The best-fit flux is still within reach of experiments such as ANITA, Auger and IceCube, however if the primary UHECRs are heavy nuclei rather than protons then the neutrino flux will be even smaller. Nevertheless there is a case for constructing even larger detectors given the potential for probing non-perturbative QCD as well as BSM physics by sudying deep inelastic scattering of such high energy neutrinos.

Speaker: Prof. Subir Sarkar (University of Oxford)

Slides Sarkar_TeVPA'11.pdf

40 Neutrino Astrophysics with the Pierre Auger Observatory

The Pierre Auger Observatory is a hybrid detector of Ultra High Energy Cosmic Rays. It has the capability of detecting ultra-high energy neutrinos of all flavours above 10$^{17}$ eV. The method adopted is to search for very inclined showers produced close to the detector. The properties of such showers that start deep in the atmosphere are different at ground level from those showers initiated in the upper atmosphere by protons or nuclei. The neutrino events will have a significant electromagnetic component leading to a broad time structure of detected signals in water Cherenkov tanks in contrast to nucleonic-induced showers. In this talk we present two analyses that are being used to identify neutrino candidates under different conditions, one for “downward-going” neutrinos and the other for “Earth-skimming” tau neutrinos. We show that the configuration of the surface detectors of the Pierre Auger Observatory has a satisfactory discrimination power against the larger background of nucleonic showers over a broad angular range. No candidates were found on data collected from 1 January 2004 and a limit on the diffuse neutrino flux is presented.

Speaker: Mr Jose Luis Navarro (Universidad de Granada)

Slides 20110802_TeVPA_jlnavarro.pdf

41 Multi-Messenger Astrophysics with the IceCube Neutrino Observatory

Simultaneous observations in different wavelengths are critical for understanding the high energy universe. The IceCube Neutrino Observatory offers the possibility to view the universe through the neutrino window, to distinguish hadronic and leptonic processes and to peer inside regions opaque to EM radiation. In many cases, the neutrinos may also be the first messengers to arrive, and thus can serve as an alert for other telescopes on the ground and in the sky. I will give an overview of IceCube multi-messenger activities, including Target of Opportunity programs coordinated with optical, x-ray, and gamma-ray instruments including ROTSE, MAGIC, and Swift; supernova alerts with SNEWS; and joint offline searches for dark bursts with the LIGO and Virgo gravitational wave detectors.

Speaker: Chad Finley (Stockholm University)

Slides Finley_TeVPA_2011.pdf

Direct searches for dark matter

42 Results of XENON100

XENON100 is a double-phase (liquid/gas) TPC aiming to directly detect WIMP Dark Matter. It is in operation underground in the Laboratori Nazionali del Gran Sasso (LNGS), Italy, and has a measured background which is below all other running Dark Matter direct detection experiments. In this talk we will present the newest results from XENON100, obtained from 100 life-days of dark matter data. No events have been found above the expected background, which leads to the lowest limit for spin-independent WIMP nucleon scattering over the whole WIMP mass range. We will concentrate on the analysis of this dataset and give an outlook.

Speaker: Dr Marc Schumann (Physik Institut, University of Zurich)

Slides tevpa_schumann_.pdf

43 An update on CoGeNT and COUPP

Recent results from CoGeNT and COUPP will be presented, as well as mention of future plans for both experiments. A short review of the uncertainties affecting searches for light-mass WIMPs will be included.

Speaker: Prof. Collar Juan (University of Chicago)

Slides COUPP-and-CoGeNT.pdf COUPP-and-CoGeNT.pdf

44 Latest Results from a Search for Spin-Dependent WIMP Interactions using the DRIFT-II Direction Sensitive Detector

We present an update on efforts to reduce the radon induced background in the DRIFT-II direction sensitive WIMP dark matter detector and the implications of this for improving sensitivity to spin- dependent interactions with a galactic directional signature. New data including operation with a fluorine target is presented along with concepts for scale-up to a new 24 m3 experiment at the Boulby underground site.

Speaker: Dr Daniel Walker (University of Sheffield)

Slides DRIFT-TeVPA.pdf

45 EDELWEISS-II WIMP search with Ge bolometers

The EDELWEISS-II collaboration has carried out a direct search for dark matter WIMPs (Weakly Interacting Massive Particles) with an array of ten 400 g germanium detectors operated at cryogenic temperatures of about 10 mK in the Modane Underground Laboratory (France). The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of gamma-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kgd has been obtained and five events have been observed above 20 keV in the region where WIMP interactions are expected with the estimated background being less than 3.0 events. The result has been interpreted in terms of limits on the cross-section of WIMP interactions with matter. Cross-sections above 4.4×10-8 pb are excluded at 90%CL for a WIMP mass of 85 GeV. This significant progress in detector sensitivity has been achieved thanks to the development of a new technique of background rejection using inter-digit electrodes. The EDELWEISS-II Collaboration is working on improving the background rejection techniques to be able to reach an order of magnitude better sensitivity in a couple of years.

Speaker: Dr Vitaly Kudryavtsev (University of Sheffield)

Slides vk-tevpa.pdf

46 Status and Future Plans of the Cryogenic Dark Matter Search Experiment

The Cryogenic Dark Matter Search (CDMS) experiment employs germanium and silicon semiconductor crystals to perform direct searches of Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs). Event-by-event discrimination between electron and nuclear recoils is achieved through simultaneous collection of charge and phonon signals. The detectors are operated at cryogenic temperatures of 50 mK at the Soudan Underground Laboratory. The latest results obtained by the CDMS-II experiment are summarised, together with the constraints on light WIMPs from a lowered 2 keV recoil energy threshold reanalysis of 8 germanium detectors. Future plans to increase the sensitivity and total detector mass in view of the SuperCDMS and GEODM experiments are also discussed.

Speaker: Dr Hassan Chagani (University of Minnesota)

Slides chagani_stockholm.pdf

Wednesday, August 3

Plenary talks

Convener: Dr Jan Conrad (Stockholm University)

47 Recent Results with Atmospheric Cherenkov Detectors

Ground-based gamma-ray instruments such as HESS, MAGIC and VERITAS make use of arrays of imaging atmospheric Cherenkov telescopes to provide sensitive measurements of astrophysical sources in the 100 GeV to 50 TeV energy range. Over the last decade, these instruments have detected ~ 100 sources that provide important data on the origin of cosmic rays and on particle acceleration in supernova blast shocks, relativistic pulsar wind-termination shocks, and accretion powered jets of supermassive black holes. These astrophysical observations also provide constraints on fundamental physics and cosmology including probes of the history of galaxy formation, Lorentz-invariance violation and even constraints on Axion-Like particles. Ground-based gamma-ray observations of the Galactic center and nearby Dwarf spheroidal galaxies are also providing constraints on particle dark matter with masses above a few hundred GeV. Here I discuss the status of particle-astrophysics measurements made with these instruments, as well as prospects for future instruments like CTA for detection of Dark Matter.

Speaker: Prof. James Buckley (Washington University)

Slides james_buckley_tevpa11.pdf

9:50 AM Coffee break

Plenary talks

Convener: Dr Jan Conrad (Stockholm Univerity)

48 PARTICLE ACCELERATION AND THE ORIGIN OF GALACTIC COSMIC RAYS

I will review the current status of our understanding of the physical processes involved in the acceleration of cosmic rays (CRs), with special attention for supernova remnants as the main candidate sources for the bulk of CRs. Recent multifrequency observations, especially in the gamma ray band, have shed new light and raised new shadows on the general framework of the origin of CRs in the Galaxy and I will discuss the new directions in which these trends are pushing our investigations, with particular emphasis on magnetic field amplification and waves in partially neutral plasmas which appear to play a crucial role to explain observations.

Speaker: Dr Pasquale Blasi Blasi (INAF/Osservatorio Astrofisico di Arcetri)

Slides TeVPA_Blasi08-2011.pdf

49 Overview of direct searches for dark matter

Speaker: Prof. Paolo Gondolo (Unviersity of Utah)

Slides Gondolo_TeVPA2011.pdf

12:00 PM Lunch break

Direct searches for dark matter

50 DM-ICE - A Search for Dark Matter Annual Modulation in South Pole Ice

An potential observable signature of dark matter linked to our galactic motion is the annual modulation of the rate of dark matter-nucleon interactions taking place in an Earth-bound experiment. To search for this effect, we introduce the concept for a new dark matter experiment using NaI scintillation detectors deployed deep in the South Pole ice. This experiment complements dark matter search efforts in the Northern Hemisphere and will investigate the observed annual modulation in the DAMA/LIBRA and DAMA/NaI experiments. The unique location will permit the study of background effects correlated with seasonal variations and the surrounding environment. The experimental concept will be described and the sensitivity of a 250 kg NaI experiment at the South Pole explored.

Speaker: Prof. Neil Spooner (University of Sheffield)

Slides TeVPA-DM-ICE0811v1.pdf

51 Light WIMPs!

Observations from the direct detection experiments DAMA/LIBRA and CoGeNT, along with those from the Gamma Ray Space Telescope, have been interpreted as possible evidence of dark matter in the form of relatively light (5-10 GeV) WIMPs. I will discuss the implications of these observations for dark matter phenomenology and discuss how it will be possible with future measurements to either confirm or refute this interpretation. I will also discuss how recent results from the Tevatron could impact efforts to build models including a light WIMP.

Speaker: Prof. Dan Hooper (Fermilab/University of Chicago)

Slides LightWIMPs-TeVPA-2011.pdf

52 Spin-dependent WIMP-nucleus elastic scattering simplified

We discuss a suitably normalized form of the isospin momentum dependent structure functions entering in the spin-dependent elastic neutralino-nucleus cross section. We compare these functions with the commonly used ones and discuss their advantages: in particular, these allow in the spin-dependent cross section to factorize the particle physics degrees of freedom from the momentum transfer dependent nuclear structure functions as it happens in the spin-independent cross section with the nuclear form factor. As an application we propose a scheme that allows to analytically determine the three elementary cross sections and connect the solutions to the relative sign between the proton and the neutron spin scattering amplitudes once the measurements of total event rate from three appropriate targets become available.

Speaker: Dr Mirco Cannoni (Universidad de Huelva, Spain)

Slides Cannoni_TeVpa2011.pdf

53 Constraining the CMSSM with dark matter direct detection results

We examine how well direct detection experiments can constrain SUSY models, using the CMSSM as an example. Various issues that affect those constraints are examined, such as our limited knowledge of the local dark matter halo and uncertainties in the parameters describing the proton & neutron structures. We discuss difficulties that arise in scanning the theoretical parameter space.

Speaker: Dr Christopher Savage (Oskar Klein Centre, Stockholm University)

Slides TeVPA_2011_-_CMSSM_and_Direct_Detection.pdf

Gamma rays - astrophysics and dark matter

54 Fermi LAT results on the intensity and origin of the diffuse extragalactic gamma-ray background

The data collected by the Fermi Large Area Telescope (LAT) over the last 3 years enable a huge step forward in measuring and understanding the origins of the extragalactic diffuse gamma-ray background (EGB). The EGB originates from the superposition of different populations of unresolved sources with possible contributions from genuinely diffuse and exotic processes. In most parts of the sky it is sub-dominant to the Galactic diffuse emission, which represents a foreground to be subtracted to allow a measurement of the EGB intensity. Due to the long exposure, an improved event selection, better understanding of the Galactic diffuse foregrounds and the charged particle backgrounds, we can now extend the measurement of the spectrum of the EGB to the energy range between 100 MeV and several hundred GeV. Additionally, population studies based on resolved LAT sources allow to constrain the contribution of individual classes of unresolved sources to the EGB.

Speaker: Markus Ackermann (DESY)

Slides EGB_ackermann.pdf

55 GeV-TeV AGN in the Fermi era

I review the characteristics of GeV-TeV emitting AGN after two years of observations with Fermi. Our view of these objects has advanced significantly since the launch of Fermi and the advent of the sensitive ground-based gamma-ray instruments, such as HESS, VERITAS and MAGIC. With these instruments we detect a large population of GeV-TeV AGN with different sub-classes and can, for the first time, measure the gamma-ray emission across 5 decades of energy. However, despite this great dataset, there remain many fundamental questions about these mysterious objects that have still to be addressed.

Speaker: Mr Stephen Fegan (LLR / Ecole Polytechnique)

Slides GeVTeV-TeVPA2011.pdf

56 Anisotropies in the diffuse gamma-ray background as measured by the Fermi-LAT

The diffuse gamma-ray background is expected to exhibit small scale anisotropies which can carry information on the underlying sources contributing to it. Astrophysical sources as well as more exotic processes like galactic or extragalactic DM annihilation are expected to leave their imprint in the pattern of the gamma-ray anisotropies. I will present the results of an angular power spectrum analysis of the high-latitude diffuse emission measured by the Fermi-LAT, and discuss the implications of the measured angular power spectrum for gamma-ray source populations that may provide a contribution to the diffuse background.

Speaker: Dr Alessandro Cuoco (Oskar Klein Center- Stockholm)

Slides StockholmTevPA2011.pdf

57 The sensitivity of air Cherenkov telescopes for anisotropies in the gamma-ray background

The indirect search for dark matter is one out of many scientific goals of gamma-astronomy. The main focus are spectral signatures of dark matter annihilation or decay in the measurements towards targets where dark matter is expected. Another possibility is to examine the anisotropy power spectrum of the $\gamma$-ray background radiation, which might exhibit a measuable signature especially in the case of annihilating dm, whose signal is proportional to the dm density square. In this presentation we investigate the possibilities of air Cherenkov teleskopes to measure the power spectrum and to distinguish between the several hypothesis of its origin.

Speaker: Dr Joachim Ripken (Stockholm university)

Slides Ripken-anisotropies.pdf

58 A new model for the extragalactic $\gamma$-ray background

We present a two-parameter model of the extragalactic $\gamma$-ray background (EGB) in the 0.1-100 GeV range as measured by the Large Area Telescope (LAT) onboard the {\it Fermi} satellite. The EGB can be fully explained as the sum of three distinct components, namely blazars, non-beamed AGNs (Seyfert galaxies and QSOs), and cosmic rays from star-forming galaxies. The contribution to the background from beamed sources is obtained by fitting the {\it Fermi}-LAT blazar differential number counts assuming that the $\gamma$-ray luminosity function is directly proportional to the radio luminosity function of FRI and FRII galaxies. The high energy emission from non-beamed AGNs is instead determined by popular synthesis models of the observed X-ray background. Finally, the EGB is fit by adding a third component arising from pion decay in cosmic rays, assuming that such component is closely linked to the cosmic star formation history. We find that blazars dominate at energies $\gsim$ 10 GeV, for $E\lsim 0.2$ GeV the main contribution is from non-beamed AGNs, while cosmic rays are required in between. Because of absorption due to interaction of $\gamma$-rays with the extra-galactic background light, our model falls short at the highest energies probed by LAT, ($\gsim 70$ GeV), leaving room to a possible contribution from dark matter particle annihilation. As an example, a particle of mass $\simeq 0.5$ TeV and cross section $\langle \sigma v \rangle \simeq 5 \times 10^{-26}$ cm$^3$ s$^{-1}$ can accomodate the data.

Speaker: Mr Massimo Cavadini (Insubria University)

Slides MCavadini_stockholm.pdf

3:30 PM Coffee break

Direct searches for dark matter

59 Prospects for constraining WIMP properties with ton-scale Dark Matter direct detection experiments

We investigate the reconstruction capabilities of Dark Matter properties from future ton-scale direct detection experiments using several targets. Adopting realistic values for the exposure, energy threshold and resolution of Dark Matter experiments which will come online within 10 years, the degree of complementarity between different targets is quantified. While a measurement of the Dark Matter mass and inelastic parameter are promisingly robust, it turns out that scalar, vector and axial couplings can only be loosely constrained. In our work, the uncertainty in the astrophysical parameters controlling the local Dark Matter density and velocity distribution is included self-consistently and translates into a significant downgrading of accuracy. However, we show that, under certain assumptions, future direct detection experiments can achieve self-calibration of some astrophysical parameters, and they will be able to constrain the Dark Matter mass with only very weak external astrophysical constraints.

Speaker: Miguel Pato (ITP Zurich)

Slides tevpa11_pato.pdf

60 WIMP astronomy with liquid-noble and cryogenic direct-detection experiments

Once weakly-interacting massive particles (WIMPs) are unambiguously detected in direct-detection experiments, the challenge will be to determine what one may infer from the data. I examine the prospects for reconstructing the local speed distribution of WIMPs in addition to their particle-physics properties (mass, cross sections) from next-generation cryogenic and liquid-noble direct-detection experiments. I show that using a more general, empirical form of the speed distribution can lead to good constraints on the speed distribution as well as the WIMP mass and cross sections. Moreover, one can use Bayesian model selection criteria to determine if a theoretically-inspired functional form for the speed distribution (such as a Maxwell-Boltzmann distribution) fits better than an empirical model. The shape of the degeneracy between WIMP mass and cross sections and their offset from the true values of those parameters depends on the hypothesis for the speed distribution, which has significant implications for consistency checks between direct-detection and collider data. In addition, I find that the uncertainties on theoretical parameters depends sensitively on the upper end of the energy range used for WIMP searches. Better constraints on the WIMP particle-physics parameters and the speed distribution are obtained if the WIMP search is extended to higher energy (~1 MeV).

Speaker: Dr Annika Peter (University of California, Irvine)

Slides tevpa2011_peter.pdf

61 Dark matter direct detection: a closer look at the astrophysical uncertainties

Although there are great expectations from the LHC to shed light on physics beyond the Standard Model and an eventual embedding of a dark matter candidate within it, a clean handle on the dark matter puzzle will come only from direct or indirect detection signals of dark matter particles within dark matter halos. There are classes of dark matter candidates for which it is indeed feasible to extract such signals, for instance measuring the interaction of a dark matter particle from the local population within a laboratory detector. A direct detection signal scales linearly with the local number density of dark matter particles and depends also on their local velocity distribution. In this talk I will show how Bayesian methods recently reduced considerably the uncertainties on those quantities. For instance, given a Galactic mass model and assuming a spherically symmetric dark matter halo, the local dark matter density can be now determined with an accuracy of approximately the 10%. I will also discuss how such an approach, combined with Eddington's inversion formula, can be used to determine the dark matter local velocity distribution.

Speaker: Dr Riccardo Catena (Institut fuer Theoretische Physik Heidelberg)

Slides TeVPA2011-catena.pdf

Gamma rays - astrophysics and dark matter

62 VERITAS Highlights on Extragalactic Gamma-ray Science

VERITAS (Very Energetic Radiation Imaging Telescope Array System) is an array of atmospheric Cherenkov telescopes sensitive to very high energy (VHE) gamma rays above 100 GeV. Located in southern Arizona, USA, the full VERITAS array of four 12m- diameter telescopes is completing its fourth year of operation. The VERITAS observation program covers a range of extragalactic objects, including blazars, radio galaxies, starburst galaxies, clusters of galaxies, dwarf spheroidal galaxies, and gamma-ray bursts. This talk will review recent results from VERITAS and our long-term science goals in the area of VHE extragalactic astrophysics.

Speaker: Dr Luis Reyes (KICP - University of Chicago)

Slides TeVPa2011_final.pdf

63 Galactic Source Highlights from VERITAS

VERITAS (Very Energetic Radiation Imaging Telescope Array System) is an array of atmospheric Cherenkov telescopes sensitive to very high energy (VHE) gamma rays above 100 GeV. Located in southern Arizona, USA, the full VERITAS array of four 12m-diameter telescopes is completing its fourth year of observations and is operating with outstanding source sensitivity. VERITAS has detected numerous Galactic sources of VHE gamma rays, including pulsar wind nebulae, supernova remnants (SNRs), binary systems, and unidentified objects. Recent highlights of the VERITAS Galactic sources program will be covered - in particular, the discovery of VHE gamma rays from the Crab Pulsar, from the SNR CTA1, and from multiple sources in the Cygnus OB1 region will be described, along with a new detection of the Galactic Center.

Speaker: Rene Ong (LLR-Ecole Polytechnique/UCLA)

Slides TeVPA2011-VERITAS-Ong.pdf

64 Intergalactic magnetic field: constraints from GeV-TeV observations of blazars

We investigate electromagnetic cascades originating from interactions with the extragalactic photon background of high energy photons emitted by blazars. We demonstrate that the non-observation of 1ES 0229+200 by Fermi-LAT indicates that a relatively strong intergalactic magnetic field (IGMF) fills more than 60% of space, favoring the primordial IGMF origin. We present also a new public code for the calculation of electromagnetic cascades in the intergalactic medium.

Speaker: Dr Sergey Ostapchenko (Norwegian University for Science and Technology (NTNU))

Slides igmf-ostapchenko.pdf

65 Testing the expansion history of the Universe with TeV photons

We show how the propagation of TeV photons differs in Universes with different expansion histories. We discuss whether it is possible to identify different cosmologies based on their opacity, discuss uncertainties associated with the observed star formation rates and show how constraints from this method adds to existing data.

Speaker: Dr Malcolm Fairbairn

Slides fairbairnstockholmtevpa.pdf

66 The cosmic X-ray and gamma-ray background from dark matter annihilation

The extragalactic background light (EBL) observed at multiple wavelengths is a promising tool to probe the nature of dark matter since it might contain a significant contribution from gamma-rays produced promptly by dark matter annihilation. Additionally, the electrons and positrons produced in the annihilation give energy to the CMB photons to populate the EBL with X-rays and gamma-rays. We have created full-sky maps of the radiation from both of these contributions using the high- resolution Millennium-II simulation. We use upper limits on the contributions of unknown sources to the EBL to constrain the intrinsic properties of dark matter using a model-independent approach that can be employed as a template to test different particle physics models (including those with a Sommerfeld enhancement). These upper limits are based on observations spanning eight orders of magnitude in energy (from soft X-rays measured by CHANDRA to gamma-rays measured by Fermi), and on expectations for the contributions from blazars and star forming galaxies. To exemplify this approach, we analyze a set of benchmark Sommerfeld- enhanced models that give the correct dark matter abundance, satisfy CMB constraints, and fit the cosmic ray spectra measured by PAMELA and Fermi without any contribution from local subhalos. We find that these models are in conflict with the EBL constraints unless the contribution of unresolved subhalos is small and the annihilation signal dominates the EBL. We conclude that provided the collisionless cold dark matter paradigm is accurate, even for conservative estimates of the contribution from unresolved subhalos and astrophysical backgrounds, the EBL is at least as sensitive a probe of these types of scenarios as the CMB. Our results disfavor an explanation of the positron excess measured by PAMELA based only on dark matter annihilation in the smooth Galactic halo.

Speaker: Dr Jesus Zavala Franco (Department of Physics and Astronomy, University of Waterloo (CITA National Fellow))

Slides DManni_EGB_TeVPA_aug11.pdf

67 Dark Matter implications of the Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background

Using the first 22 months of data, the Fermi-LAT collaboration measured the angular spectrum (APS) of anisotropies in the diffuse gamma-ray background. Results indicate the detection of angular signal with a significance of few sigma. The APS is consistent with being independent from multipole (for multipoles larger than 154) and this is compatible with the contribution from one or more populations of unresolved, unclustered gamma-ray emitters. In this study we use Fermi-LAT measurement of the APS to constrain a possible contribution from Dark Matter (DM) to the APS. The DM distribution is modeled exploiting the results of the most recent N-body simulations, considering both the contribution of extragalactic halos and subhalos (from Millennium-II) and of Galactic substructures (from Aquarius). Both the cases of an annihilating and decaying DM candidate are considered. Moreover, with the use of the Fermi Science Tools, these DM maps serve as templates to produce mock gamma-ray count maps for DM gamma-ray emission. The APS will then be computed and compared to the Fermi-LAT results in order to derive constraints on the DM particle physics properties. We also estimate the uncertainties on the APS due our imperfect knowledge of DM distribution, as well as the possible systematic due to a residual contamination of the Galactic foreground.

Speaker: Mr Mattia Fornasa (Instituto de Astrofisica de Andalucia (IAA - CSIC))

Slides MattiaFornasa_TeVPA2011.pdf

Particle Physics

68 Implications of LHC Higgs Searches for Neutralino Dark Matter

One of the main channels which allows for a large rate of neutralino dark matter annihilation in the early Universe is via the Higgs pseudoscalar $A$-resonance. In this case, the measured dark matter abundance can be obtained in the minimal supergravity (mSUGRA) model when $\tan\beta\sim 50$ and $2m_{\chi_1}\sim m_A$. We investigate the reaction $pp\to b\phi\to b\mu^+\mu^- +X$ (where $\phi =A$ or $H$). The rare but observable Higgs decay to muon pairs allows for a precise measurement of the Higgs boson mass and decay width. We find that $\Gamma_A$ can typically be determined to $\sim 8\%$ ($\sim 17\%$) for $m_A\sim 400$ (600) GeV and $10^3$ fb$^{-1}$ of integrated luminosity. In the case where a dilepton mass edge from $\chi_2\to\ell^+\ell^- \chi_1$ is visible, it should be possible to test the relation that $2m_{\chi_1}\sim m_A$.

Speaker: Prof. Chung Kao (University of Oklahoma)

Slides TeVPA2011_Kao.pdf

7:00 PM Reception and guided tour of the city hall

Thursday, August 4

Plenary talks

Convener: Prof. Joakim Edsjö (Stockholm University)

69 TeV Astrophysics with Extensive Air Shower Arrays

Ground-based gamma-ray astronomy has historically implemented two dramatically different techniques. One method employs Imaging Atmospheric Cherenkov Telescope(s) (IACT) that detect the Cherenkov light generated in the atmosphere by extensive air showers. The other method employs particle detectors that directly detect the particles that reach ground level - known as Extensive Air Shower (EAS) arrays. Until recently, the IACT method had been the only technique to yield solid detections of TeV gamma-ray sources. Utilizing water Chernkov technology, Milagro, was the first EAS array to discover new gamma-ray sources and demonstrated the power of and need for an all-sky high duty cycle instrument in the TeV energy regime. The transient nature of many TeV sources, the enormous number of potential sources, and the existence of TeV sources that encompass large angular areas all point to the need for an all-sky, high duty-factor instrument with even greater sensitivity. In this talk I will discuss recent results from the current generation of EAS arrays and the future instruments that are currently planned with dramatically improved sensitivity.

Speaker: Dr Gus Sinnis (Los Alamos National Laboratory)

Slides Sinnis-EAS.pdf

9:50 AM Coffee break

Distribution of dark matter

70 Dark Matter distribution on large and small scales

I will summarize current results based on cosmological simulations about the distribution of Dark Matter on both large and small scales. I will show how the distribution of DM can be influence by the nature of the dark matter candidate (Warm vs Cold), by the modeling of Dark Energy and by the presence of baryons.

Speaker: Dr Andrea Maccio (Max Planck Institute for Astronomy)

Slides Maccio.pdf

71 Dark Matter spikes constraints on WIMPS from 1 GeV-10 TeV from Fermi

10 to 10^5 solar mass black holes with dark matter spikes that formed in early minihalos and still exist in our Milky Way Galaxy today are examined in light of recent data from the Fermi Gamma-Ray Space Telescope (FGST). The dark matter spikes surrounding black holes in our Galaxy are sites of significant dark matter annihilation. We examine the signatures of annihilations into gamma-rays, electrons and positrons, and neutrinos. We find that some significant fraction of the point sources detected by FGST might be due to dark matter annihilation near black holes in our Galaxy. We obtain limits on the properties of dark matter annihilations in the spikes using the information in the FGST First Source Catalog as well as the diffuse gamma- ray flux measured by FGST. We determine the maximum fraction of high redshift minihalos that could have hosted the formation of the first generation of stars and, subsequently, their black hole remnants. The strength of the limits depends on the choice of annihilation channel and black hole mass; limits are strongest for the heaviest black holes and annhilation to $b \bar{b}$ and $W^+W^-$ final states and also to the lightest WIMPS thus dm spikes offer strong constraints on light WIMPs

Speaker: douglas spolyar (FNAL)

Slides Spolyar-TEVPAstockholm.pdf

72 Dark matter annihilation signatures in stellar oscillations and nuclear clusters

Strong deviations from the classical picture of stellar evolution are predicted when low-mass stars are embedded in halos of dark matter (DM) particles with very high densities, such as those expected in the inner parsec of our galaxy. In this talk we will focus on two possible strategies to detect the influence of the DM captured inside low-mass stars. First, by looking at the signatures of DM annihilation on the stellar oscillations. Second, describing the impact on the appearance of a whole stellar cluster, comparing the shape of the isochrones computed for a cluster within a dense DM halo with those predicted for a classical stellar cluster.

Speaker: Jordi Casanellas (CENTRA-IST, Lisbon)

Slides Casanellas_TeVPA2011.pdf

73 Dark Matter Distribution in Dwarf Galaxies and Globular Clusters

The dark matter distribution in dwarf galaxies and potentially in globular clusters is of great interest for indirect dark matter searches. In order to understand the distribution of dark matter in the smallest observable structures, we investigate the evolution of the radial density profile of dwarf spheroidal galaxies and globular clusters. We present first results from a very high resolution cosmological simulation of a small patch of the Universe where we follow the formation history of massive star clusters and the first dwarf galaxies. We discuss the effect of baryonic processes on the slope of the dark matter distribution. We briefly comment on the implications of our results for indirect dark matter probes.

Speaker: Mr Pascal Steger (Institute for Astronomy, ETH Zurich)

Slides TeVPA_2011_Steger_20110804.pdf

Gamma rays - astrophysics and dark matter

74 From Hazes to Bubbles in the Inner Galaxy

Observations of the gamma-ray sky by the Fermi Gamma-ray Space Telescope have revealed a striking sharp-edged, double-lobed structure in 1-100 GeV gamma rays, centered on the Galactic Center and extending 50 degrees north and south of the Galactic plane. The gamma-rays associated with these "Fermi bubbles" have a significantly harder spectrum than emission spatially correlated with maps of the SFD dust and radio synchrotron, or with the diffuse model provided by the Fermi collaboration. Possibly associated signals can be seen in microwaves (associated with the WMAP Haze) and 1.5-2 keV X-rays. I will describe the methods used to identify and analyze the bubbles, characterize their spectrum and morphology, discuss their relation to the Fermi and WMAP "Hazes" and the implications for dark matter searches, and outline some possible interpretations and the challenges involved in explaining all aspects of the signal.

Speaker: Dr Tracy Slatyer (Institute for Advanced Study)

Slides TeVPA11_Slatyer.pdf

75 Fermi Bubbles from Sustained Galactic Centre Star Formation

I will show that the recently-discovered Fermi Bubbles are naturally explained as due to a population of relic cosmic ray protons and heavier ions injected by processes associated with sustained, extremely long timescale and high areal density star- formation in the Galactic center. In our picture, the Bubbles are essentially calorimetric recordings of Galactic centre activity over the last few billion years.

Speaker: Dr Roland Crocker (MPIK Heidelberg)

Slides Stockholm_2011_Crocker_talk.pdf

76 Fermi gamma-ray `bubbles' from stochastic acceleration of electrons

Gamma-ray data from Fermi-LAT reveal a bi-lobular structure extending up to 50 degrees above and below the galactic centre, which presumably originated in some form of energy release there less than a few million years ago. It has been argued that the gamma-rays arise from hadronic interactions of high energy cosmic rays which are advected out by a strong wind, or from inverse-Compton scattering of relativistic electrons accelerated at plasma shocks present in the bubbles. We explore the alternative possibility that the relativistic electrons are undergoing stochastic 2nd-order Fermi acceleration by plasma wave turbulence through the entire volume of the bubbles. The observed gamma-ray spectral shape is then explained naturally by the resulting hard electron spectrum and inverse Compton losses. Rather than a constant volume emissivity as in other models, we predict a nearly constant surface brightness, and reproduce the observed sharp edges of the bubbles.

Speaker: Dr Philipp Mertsch (Rudolf Peierls Centre for Theoretical Physics, University of Oxford)

Slides Mertsch_TeVPA2011.pdf

77 The Fermi haze from Dark Matter Annihilation and Anisotropic Diffusion

The Fermi haze is a diffuse component of gamma-ray emission centered towards the galactic center, extending up to approximately $\pm$50 degrees in latitude, recently revealed after analysis of full-sky map data from the Fermi LAT instrument. The Fermi ``haze'' is the gamma-ray counterpart generated by inverse Compton emission from the same population of electrons which generate the microwave synchrotron haze observed at WMAP wavelengths, with two distinct characteristics: its significantly harder spectrum than the emission elsewhere in the Galaxy and its morphology that is elongated along the latitude with respect to the longitude with an axis ratio ~2. If dark matter annihilation, in the Galactic halo, is responsible for producing those electrons, the standard spherical halo and isotropic diffusion of cosmic rays in the Galaxy can not explain the elongated morphology of the signal. Yet, the presence of ordered magnetic field towards the center of the Galaxy can cause cosmic rays to diffuse anisotropically along the ordered field lines. Also dark matter halos have been shown to be generically triaxial by cosmological simulations. The combination of a prolate dark matter halo and anisotropic diffusion can easily yield the required morphology of the signal without making unrealistic assumptions about the galactic magnetic field while also being consistent with local cosmic-ray measurements as well as CMB constraints. A Sommerfeld enhancement to the annihilation cross-section of ~30 yields a good fit to the morphology, amplitude, and spectrum of both the gamma-ray and microwave haze. Finally, such DM models, can give a very different neutrino signal as compared to astrophysical models suggested in order to explain the Fermi haze signal.

Speaker: Dr Ilias Cholis (SISSA/ISAS)

Slides TeVPA_2011_DM_FermiHaze_Cholis_2.pdf

78 Dark Matter and the Galactic Center Radio Filaments

Regions of enhanced synchrotron emission with unusually hard spectra – known as the non-thermal radio filaments – have attracted significant interest due difficulty in modeling their synchrotron spectra with astrophysical electron injection spectra. We show that the synchrotron emission from these regions may be connected to recent Fermi-LAT observations showing excess gamma-ray emission near the galactic center. Specifically, we find that a light, and leptophilic dark matter profile previously employed to explain the Fermi gamma-ray excess will inject leptons with the correct intensity and spectrum to explain the synchrotron signal observed in the filamentary arcs.

Speaker: Mr Tim Linden (Fermilab / UCSC)

Slides Filaments.pdf

12:00 PM Lunch break

Distribution of dark matter

79 Gravitational Lenses of the Dark Universe

Gravitational lensing, which occurs when the light from distant objects is bent as it passes by matter, is a uniquely powerful tool in astronomy. It allows us to make direct measurements of the unseen components of the Universe, including dark matter and dark energy, which dominate the Universe around us but are not understood. Explaining these two dark components remains one of the key unresolved issues in fundamental physics today. This lecture will introduce the basic physical principles of gravitational lensing and show how it can be used on cosmological scales to measure the properties of dark matter and dark energy. The focus will be on a gravitational lensing technique known as 'cosmic shear', which has allowed us to map the three-dimensional distribution of the dark matter around us. In addition to its potentials in exploring dark matter and dark energy, the utility of gravitational lensing extends well beyond cosmology. It can be used to measure the detailed dynamics of stars, as well as detecting large populations of Earth-like planets outside our solar system. We will conclude by discussing how on-going and future experiments in cosmic shear will continue to give us unprecedented insights into the inner workings and evolutionary history of the Universe.

Speaker: Dr Adam Amara (ETH Zurich)

80 Dark Matter distribution in the central region of the Galaxy

Dark Matter distribution in the central region of the Galaxy

Speaker: Fabio Iocco (Institute d'Astrophysique de Paris)

Slides Iocco-MicroLensing.pdf

81 Limits on the local dark matter density

We revisit the systematic problems that arise in determining the local matter and dark matter density from the vertical motion of stars at the Solar Neighbourhood. We use a simulation of a Milky Way-like galaxy to analyse these systematics and determine the quality of data required to detect dark matter at its expected local density. We introduce new unbiased method for recovering ρ_DM, based on moments of Jeans equation, combined with a Monte Carlo Markov Chain technique to marginalise over the unknown parameters. Our method relies on a 'minimal' set of hypotheses and recovers the correct value of ρ_DM even in face disc of inhomogeneities, non-isothermal tracers and a non-separable distribution function, but requires more precise data than the classical method adopted in the literature.

Speaker: Ms Silvia Garbari (ITP - University of Zürich)

Slides s_garbari.pdf

Gamma rays - astrophysics and dark matter

82 Probing Systematic Uncertainties in Diffuse Galactic Emission Modeling with Fermi LAT

The high energy diffuse emission originates when cosmic-rays (CRs) interact with the interstellar medium (ISM) and interstellar radiation field (ISRF). It is the dominant source of gamma-rays in the Fermi-LAT data, accounting for more than half of the photons. Observations of the diffuse emission can be used to explore CR origin and propagation in the Milky Way when combined with modeling of the diffuse emission. We utilize the GALPROP code to create a grid of models by varying within observational limits the size of the propagation halo, the CR source distribution and the interstellar gas distribution. The models are compared to 21 months of Fermi-LAT data using an all sky maximum likelihood fit where we determine the radial distribution of the X_CO factor, a normalization factor for the ISRF, the spectral shape of the sources from the first Fermi-LAT catalog, and the spectral shape of the isotropic background, all of which have some dependence on the assumed diffuse emission model. The models are compared on their maximum likelihood ratio, as well as spectra, longitude and latitude profiles, and residual maps.

Speaker: Dr Gudlaugur Johannesson (Science Institute, University of Iceland)

Slides Johannesson-DiffuseSystematics_v3.pdf

83 The GeV-TeV Galactic gamma-ray diffuse emission

The Galactic gamma-ray diffuse emission is currently observed in the GeV-TeV energy range with unprecedented accuracy by the Fermi satellite. Understanding this component is crucial as it provides a background to many different signals such as extragalactic sources or annihilating dark matter. It is timely to reinvestigate how it is calculated and to assess the various uncertainties which are likely to affect the accuracy of the predictions. The Galactic gamma-ray diffuse emission is mostly produced above a few GeV by the interactions of cosmic ray primaries impinging on the interstellar material. The theoretical error on that component is derived by exploring various potential sources of uncertainty. Particular attention is paid to cosmic ray propagation. Nuclear cross sections, the proton and helium fluxes at the Earth, the Galactic radial profile of supernova remnants and the hydrogen distribution can also severely affect the signal. The propagation of cosmic ray species throughout the Galaxy is described in the framework of a semi- analytic two-zone diffusion/convection model. This allows to convert the constraints set by the boron-to-carbon data into a theoretical uncertainty on the diffuse emission. New deconvolutions of the HI and CO sky maps are also used to get the hydrogen distribution within the Galaxy. The thickness of the cosmic ray diffusive halo is found to have a significant effect on the Galactic gamma-ray diffuse emission while the interplay between diffusion and convection has little influence on the signal. The uncertainties related to nuclear cross sections and to the primary cosmic ray fluxes at the Earth are significant. The radial distribution of supernova remnants along the Galactic plane turns out to be a key ingredient. As expected, the predictions are extremely sensitive to the spatial distribution of hydrogen within the Milky Way.

Speaker: Dr Timur Delahaye (Madrid UAM/CSIC)

Slides TeVPA.pdf

84 A Robust Approach to Constraining Dark Matter Properties with Gamma-Ray Data

We present a new technique for using gamma-ray data to constrain the properties of dark matter that makes minimal assumptions about the dark matter and the backgrounds. The technique relies on two properties of the expected signal from annihilations of the smooth dark matter component in our galaxy: 1) it is approximately rotationally symmetric around the axis connecting us to the galactic center, and 2) variations from the mean signal are uncorrelated from one pixel to the next. We apply this technique to recent data from the Fermi telescope to generate constraints on the dark matter mass and cross section for a variety of annihilation channels.

Speaker: Eric Baxter (Department of Astronomy and Astrophysics, The University of Chicago)

Slides baxter_tevpa2011-web.pdf

85 Dark Matter Limits From The Galactic Halo With H.E.S.S.

The H.E.S.S. Cherenkov telescope array, which observes the universe in the very-high-energy (VHE, E > 100 GeV) gamma-ray domain, is involved in indirect searches for particle Dark Matter (DM). Observations towards regions with presumably high DM density like dwarf galaxies or cores of nearby galaxies have been conducted over the last years. Available data of the Galactic Center was reanalyzed with DM search in mind as well as new observations were conducted. In this talk, past results and present activities of the H.E.S.S. experiment concerning the search for DM in the galactic center region will be presented.

Speaker: Mr Emrah Birsin (Humboldt-University Berlin)

Slides BirsinTeVPA2011.ppt

3:00 PM Coffee break

Distribution of dark matter

86 Prospects for Indirect Detection of Dark Matter in Dwarf Galaxies

Of all galaxy types, the Milky Way's dwarf spheroidal (dSph) satellites have the largest inferred dark matter densities and smallest measured baryonic masses. These facts combine to make dSphs attractive targets for indirect detection of dark matter via self-annihilation and/or decay events. A detection (or non-detection) of high-energy photons that might be released in such processes constrains the nature of the dark matter particle only insofar as we know the distribution of dark matter within the emitting halo. I will discuss the inference of dSph dark matter distributions from observed stellar kinematics, placing particular emphasis on the potential for systematic errors. In this context I will then present an analysis of dSph stellar kinematics that makes minimal assumptions about the shape of the underlying dark matter density profile. This analysis yields up-to-date constraints on the 'astrophysical' component of a dark matter signal that can then be applied to current and future observations aimed at indirect detection.

Speaker: Dr Matthew Walker (Harvard-Smithsonian Center for Astrophysics)

Slides walker_stockholm.pdf

87 Measuring the DM halo profile of dwarf spheroidal galaxies

Dwarf spheroidal galaxies (dSphs) are the most dark matter(DM) dominated and densest galaxies in the known Universe. As such they provide interesting cases for indirect DM detection experiments. Unfortunately, deriving the distribution of DM in dSphs is severely hampered by the strong degeneracy that exists between the stellar velocity anisotropy and enclosed DM mass. Here I will present a new method for measuring the slopes of mass profiles within dSphs directly from stellar spectroscopic data and without adopting a particular DM halo model. This method combines two recent results: 1) spherically symmetric, equilibrium Jeans models imply that the product of half-light radius and (squared) stellar velocity dispersion provides an accurate estimate of the mass enclosed within the stellar half-light radius and 2) some dSphs have chemo-dynamically distinct stellar subcomponents that independently trace the same gravitational potential. Our method uses measurements of stellar positions, velocities and spectral indices of individual stars to statistically estimate the half-light radii and velocity dispersions of both subcomponents. For a dSph with two detected stellar subcomponents, this procedure yields estimates of masses enclosed at two discrete points in the same mass profile, immediately defining a slope. I will present preliminary results for two dSphs that show spatially and kinematically distinct stellar populations: Fornax and Sculptor.

Speaker: Dr Jorge Penarrubia (IoA, University of Cambridge)

Slides penarrubia.pdf

Gamma rays - astrophysics and dark matter

88 The HAWC gamma ray observatory

The High Altitude Water Cherenkov (HAWC) observatory is a ground based very high-energy gamma ray detector under construction in Mexico at an altitude of 4100 m. Higher altitude, improved design and a larger physical area used for triggering and background discrimination makes HAWC 15 times more sensitive to Crab-like spectra than its predecessor Milagro. HAWC's large field of view (~2sr) and near 100% duty cycle make it ideal to search for transient sources such as AGNs and GRBs as well as to conduct unbiased surveys of galactic and extragalactic over a large fraction of the sky. The status of the HAWC project and its scientific prospects will be discussed.

Speaker: Ignacio Taboada (Georgia Institute of Technology)

Slides TeVPA_Taboada_HAWC.pdf

89 Detecting TeV Gamma-rays from GRB with km$^3$ neutrino telescopes

This is a preliminary study to examine the prospect of detecting TeV photons from $\gamma$-ray bursts (GRB) using km-size neutrino telescope, specifically for the ANTARES neutrino telescope. Although optimized to detect upgoing neutrino-induced muons, km$^3$ neutrino telescopes nevertheless has a potential to detect high-energy photons by detecting downgoing muons from electromagnetic cascade induced by the interaction of TeV photons with The Earth's atmosphere. The photon energy spectrum of a GRB is modeled by a simple power law and is normalized by simple energetic considerations. Taking into account the absorption of TeV photons by cosmic infrared backgrounds, the arriving number of photons on top of The Earth atmosphere is determined. Muon production in the atmosphere is determined by considering two main channels of muon productions: Pion photoproduction and direct muon pair production. The muon energy loss during their traverse from the surface to the bottom of the sea is determined using the standard muon energy loss formula. Assuming different detector sizes, the total of number of signals from single GRB events located at different redshifts and zenith distances is determined. Assuming background noises consisting of cosmic ray-induced downgoing muons, the detection significance is calculated. It is concluded that to obtain at least $3\sigma$ detection significance, a GRB has to be located at redshift $z \lesssim 0.07$ if the detector's muon effective area is $A^{\mu}_{\rm eff} \sim 10^{-2}\;{\rm km}^{2}$, or redshift $z \lesssim 0.15$, if the muon effective area is $A^{\mu}_{\rm eff} \sim 1\;{\rm km}^{2}$.

Speaker: Mr Tri L. Astraatmadja (Nikhef)

Slides astraatmadja_TeVPA2011_phot_from_GRB.pdf

90 GAMMA-400 SPACE MISSION

GAMMA-400 is a space mission included in the Russian Federal Space Program and supported by the Russian Federal Space Agency. The main characteristics of the mission are a high elliptical orbit (initial parameters: perigee 500 km, apogee 300 000 km), a total mass for the scientific payload of 2600 kg, and a power budget for the instrument of 2 kW. The experiment is intended to improve the angular and energy resolutions obtained by other space missions for gamma-ray and electron detections in the 0.1-3000 GeV energy range. For 100 GeV gamma rays, the expected angular and energy resolutions are ~0.01° and ~1%, respectively. The apparatus will consist of a finely segmented converter/tracker (made by thin tungsten layers and sensitive planes of silicon microstrip detectors), and a deep (≈ 25X0) homogeneous imaging calorimeter for energy measurement. On the top of the Si-W converter/tracker, a light multilayer silicon tracking detector will extend the GAMMA-400 measuring capabilities for low- and medium-energy gamma rays in the range 50-300 MeV. GAMMA-400 will permit to identify many discrete gamma-ray sources, in particular at the center of the Galaxy, to study the diffuse gamma-ray background, and to precisely investigate gamma-ray energy spectrum features in a wide energy range. The homogeneous and deep calorimeter, besides providing excellent energy resolution and rejection power, can also be used to measure cosmic-ray protons and nuclei entering from the sides, thus achieving a total GF for nuclei exceeding 1 m2sr and enabling the measurement, in a few years, of the proton flux beyond 1 PeV and the helium flux beyond 0.5 PeV/nucleon.

Speaker: Dr Sergey Suchkov (P.N.Lebedev Physical Institute of the Russian Academy of Sciences)

Slides GAMMA-400-spase-mission.pdf

6:00 PM Conference dinner / boat tour

Friday, August 5

Plenary talks

Convener: Prof. Olga Botner (Uppsala University)

91 New Physics Searches at the LHC - Recent Results from ATLAS and CMS

This talk will review recent results from searches for physics beyond the Standard Model performed by ATLAS and CMS, namely the search for the Higgs, for Supersymmetry signatures, or other new phenomena. Where possible updated results from the 2011 LHC running at sqrt(s) = 7 TeV will be included.

Speaker: Dr David Berge (CERN)

Slides Berge.TeVPA2011.pptx

9:50 AM Coffee break

Plenary talks

Convener: Prof. Olga Botner (Uppsala University)

92 The distribution of dark matter (observations and simulations)

I discuss the observed distribution of dark matter on scales from galaxy clusters to nearby dwarf galaxies and the Solar neighbourhood. By comparing these observations with numerical simulations, we can already place interesting constraints on dark matter models: the data are consistent with dark matter being a cold, weakly interacting particle, while dark matter as alternative gravity is strongly disfavoured. I go on to discuss how the observed distribution of dark matter locally has a vital role to play in direct and indirect dark matter search experiments. I discuss where best to look for dark matter annihilation signals, and give new constraints on the local dark matter density and velocity distribution.

Speaker: Prof. Justin Read (ETH- Zurich & University of Leicester)

Slides darkmatter_stockholm.pdf

93 Recent results from the Fermi Large Area Telescope

The Large Area Telescope (LAT) on the $Fermi$ mission began routine science operations almost exactly three years ago, on August 4, 2008, and has operated nearly flawlessly and stably. It has surveyed the sky in the 20 MeV to >300 GeV energy range with unprecedented depth and resolution and frequency of coverage. The rate of scientific return from the LAT continues to be high. I will present an overview of recent work, including general LAT catalogs and studies of source populations, investigations of transient sources as varied as the Sun, the Crab Nebula, and gamma-ray bursts, results on cosmic-ray production in the Milky Way, studies of diffuse Galactic and extragalactic gamma-ray emission, and limits on WIMP dark matter.

Speaker: Seth Digel (KIPAC/SLAC)

Slides Recent_Fermi_Results_TeVPA2011_Digel_v2.pdf Recent_Fermi_Results_TeVPA2011_Digel_v2.ppt

94 Concluding remarks and announcement of TeVPA 2012

Speaker: Prof. Gianfranco Bertone (ITP Zurich)

Slides Presentazione.pdf

12:05 PM Lunch break

Gamma rays - astrophysics and dark matter

95 Constraining dark matter signal from a combined analysis of Milky Way satellites with the Fermi-LAT

Dwarf spheroidal galaxies have a large mass to light ratio and low astrophysical background, and are therefore considered one of the most promising targets for dark matter searches in the gamma-ray band. The Fermi-LAT sensitivity to gamma-ray sources can be improved through the use of a combined likelihood analysis, which in the event of a null detection, yields enhanced constraints on dark matter parameter space. From a combined analysis of the Fermi-LAT data for 10 dwarf spheroidal galaxies, we derive robust constraints on the dark matter annihilation cross section for multiple channels accounting for astrophysical uncertainties.

Speaker: Ms Maja Llena Garde (Oskar Klein Centre, Stockholm University)

Slides Maja_TeVPA2011.pdf

96 Combined Analysis on Clusters of Galaxies with the Fermi-LAT - Gamma Ray Emission from Cosmic Rays and Dark Matter

Clusters of Galaxies are the largest virialized structures in the universe. Radio observations indicate the presence of a relativisitic electron population that can give rise to a distinct gamma-ray signature through scattering with low energy photons. In addition, gamma-rays can result from collisions of cosmic ray protons with particles in the intracluster medium through subsequent $\pi^0$ decay. Moreover, clusters of galaxies possess high mass-to-light ratios, making them interesting targets for indirect dark matter searches. In this case, gamma rays may be produced from the decay or annihilation of dark matter particles. The predicted gamma-ray spectra for clusters of galaxies is distinct from the diffuse galactic and extragalactic background emission making them an exciting potential source class for the Fermi-LAT. The spectral characteristics of dark matter annihilation or decay and of cosmic ray emission are expected to be universal in different clusters, making a combined statistical treatment feasible. We present a combined likelihood analysis and set limits on the Dark Matter annihilation cross section or decay time and on the hadron injection efficiency.

Speaker: Mr Stephan Zimmer (CoPS, Fermi-LAT)

Slides zimmer.combined-clusters.pdf

97 CLUES on Fermi-LAT prospects for munuSSM gravitino dark matter extragalactic detection

The munuSSM is a supersymmetric model that has been proposed to solve the problems of other supersymmetric extensions of the standard model. The gravitino is a natural candidate for dark matter in the munuSSM and could be detectable through the emission of a monochromatic gamma ray in a two-body decay. We study the prospects of the Fermi-LAT telescope to detect such monochromatic lines in 5 years of observations of the most massive extragalactic objects. The dark matter halo around the Virgo galaxy cluster is selected as a reference case, since it is associated to a particularly high signal-to-noise ratio and is located in a region scarcely affected by the presence of astrophysical point sources. The simulation of both signal and background gamma-ray events is carried out with the Fermi Science Tools, and the dark matter distribution around Virgo is taken from a $N$-body simulation with constrained initial conditions provided by the CLUES project. We find that a gravitino with a mass range of 0.5--10 GeV approximately, and with a lifetime of about 5e27 s (1e28 s) would be detectable by the Fermi-LAT with a signal-to-noise of 5 (3).

Speaker: Mr German Gomez-Vargas (IFT UAM/CSIC Madrid - INFN Roma Tor Vergata)

Slides German_Gomez_Vargas_TEVPA_2011_gravitino_Fermi_CLUES.pdf

98 Spectral Cutoffs in Indirect Dark Matter Searches

Indirect searches for dark matter annihilation or decay products in the cosmic-ray spectrum are plagued by the question of how to disentangle a dark matter signal from the omnipresent astrophysical background. One of the practically background-free `smoking gun' signatures for dark matter would be the observation of a sharp cutoff in the gamma-ray energy spectrum. Such a feature is generically produced in many dark matter models by internal Bremsstrahlung, and it can be treated in a similar manner as the traditionally looked-for gamma-ray lines. In this talk, we will discuss prospects for seeing such features with present and future gamma-ray telescopes. We will concentrate on Air Cherenkov Telescopes and comment on the Fermi LAT.

Speaker: Dr Christoph Weniger (Max-Planck-Institut für Physik, München)

Slides weniger_web.pdf

99 Overcoming Gamma Ray Constraints with Annihilating Dark Matter in Milky Way Subhalos

We reconsider Sommerfeld-enhanced annihilation of dark matter (DM) into leptons to explain PAMELA and Fermi electron and positron observations, in light of possible new effects from substructure. There is strong tension between getting a large enough lepton signal while respecting constraints on the fluxes of associated gamma rays. We first show that these constraints become significantly more stringent than in previous studies when the contributions from background e^+ e^- are taken into account, so much so that even cored DM density profiles are ruled out. We then show how DM annihilations within subhalos can get around these constraints. Specifically, if most of the observed lepton excess comes from annihilations in a nearby (within 1 kpc) subhalo along a line of sight toward the galactic center, it is possible to match both the lepton and gamma ray observations. We demonstrate that this can be achieved in a simple class of particle physics models in which the DM annihilates via a hidden leptophilic U(1) vector boson, with explicitly computed Sommerfeld enhancement factors. Gamma ray constraints on the main halo annihilations (and CMB constraints from the era of decoupling) require the annihilating component of the DM to be subdominant, of order 10^-2 of the total DM density.

Speaker: Mr Aaron Vincent (McGill University)

Slides TeVPA_AaronVincent.pdf

Particle physics

100 Constraints on the dark matter properties from radiative decays

Dark matter particles which decay into charged fermions produce, via radiative corrections, monoenergetic gamma rays with a branching ratio that depends on the details of the dark matter model. We analyze in this talk the prospects to detect monoenergetic gamma-rays from radiative dark matter decays at present and future experiments. We also discuss the implications for concrete models of decaying dark matter, concretely those which can explain the electron/positron excesses observed by PAMELA and the Fermi-LAT.

Speaker: Alejandro Ibarra (TUM)

Slides Ibarra.pdf

101 The GERDA Experiment: A Search for Neutrinoless Double Beta Decay

The GERDA experiment uses the neutrinoless double beta decay to probe three fundamental questions in neutrino physics - Are they Dirac or Majorana particles? What is their absolute mass? What is the mass hierarchy of the three generations? It uses high-purity germanium detectors enriched in Ge-76 which are submerged nakedly in liquid argon. Due to an expected half life of the neutrinoless double beta decay of T_1/2 ~ 10e25 y, background reduction is essential. Therefore the experiment is located 1500 m (3400 mwe) underground at LNGS, Italy and is further shielded with water, which also acts as active veto, as well as liquid argon. The construction of the experiment finished in summer 2010 and the commissioning is in its finale stage. The start of a first physics run is expected in summer 2011. This talk will give an overview of the experiment, its current status and first results.

Speaker: Ms Francis Froborg (University of Zurich)

Slides TeV11_Froborg.pdf

102 keV sterile neutrino Dark Matter as alternative to the TeV scale

When thinking about Dark Matter, one always has the typical WIMP with a mass of a few 100 GeV in mind. In this talk, we will argue that another valid possibility is to have sterile neutrinos at the keV scale ("Warm Dark Matter"), which can yield the correct Dark Matter abundance when, e.g., produced non-thermally. The crucial advantage of this framework is that we need some type of right-handed neutrino to explain neutrino masses, which suggests an interesting connection of the Dark Matter problem to particle physics model building. We will explain these connections and present the most interesting models on the market.

Speaker: Dr Alexander Merle (Royal Institute of Technology (KTH))

actual talk TeVPA_Merle.pptx

Slides TeVPA_Merle.pdf

103 Number-theory dark matter

We propose that the stability of dark matter is ensured by a discrete subgroup of the U(1)B-L gauge symmetry, Z_2(B-L). We introduce a set of chiral fermions charged under the U(1)B-L in addition to the right-handed neutrinos, and require the anomaly- cancellation conditions associated with the U(1)B-L gauge symmetry. We find that the possible number of fermions and their charges are tightly constrained, and that non- trivial solutions appear when at least five additional chiral fermions are introduced. The Fermat theorem in the number theory plays an important role in this argument. Focusing on one of the solutions, we show that there is indeed a good candidate for dark matter, whose stability is guaranteed by Z_2(B-L).

Speaker: Prof. Fuminobu Takahashi (Tohoku University)

Slides Takahashi.key Takahashi.pdf

3:30 PM Coffee break

Gamma rays - astrophysics and dark matter

104 Particle acceleration in Supernova remnants

Recent years have brought significant advances in our understanding of particle acceleration in Supernova remnants. These have come both through new observational data, most notably through gamma-ray observations with instruments such as Fermi- LAT and the current generation of Imaging Atmospheric Cherenkov Telescopes (IACT) as well as through an improvement in the theoretical understanding of shock acceleration and magnetic field amplification. I will review the observational status of Supernova remnant research and describe the results that can be drawn to understand particle acceleration.

Speaker: Prof. Stefan Funk (SLAC National Accelerator Center and Stanford University)

Slides Funk_2011_Stockholm_TeVPA.pdf

105 Pulsar Wind Nebulae: recent advances in the TeV range

In the last years, the observation of the Galactic plane by the third generation of Cerenkov Telescopes, mainly done by H.E.S.S., has revealed that pulsar wind nebulae (PWN) are the largest source class in the Galaxy. The TeV observational characteristics of those objects can be divided into two sub-classes : the compact and centre-filled sources, mainly associated with young pulsars, and the middle aged ones, which present extended and offset nebulae. The very high energy emission from PWNe gives another point of view on the underlying electron population injected by the pulsar, and gives access to useful information such as an estimate of the magnetic field, and also, thanks to the longer life time of the emitting electrons, to the history of particle injection. Moreover, the increasing number of detected PWNe enables to perform population studies, which will help to constrain the different physical characteristics of this population. Here, we present recent results on PWNe and discuss progresses in the understanding of these objects, in the light of the large number of TeV detections.

Speaker: Dr Vincent Marandon (MPIK Heidelberg)

Slides Marandon_TevPA2011v1.pdf

106 Gamma ray emission from molecular clouds in association with close by supernova remnants

The detection of very-high-energy gamma-rays from supernova remnants (SNR) has proven, that particles are accelerated in shock waves of the SNRs up to energies of about 100 TeV. Theoretical models predict, that SNRs can accelerate particles up to energies of several 10^15 TeV within the first 1000 years after the supernova explosion. Due to this short time span, the number of SNRs at this stage of their evolution is rare and hard to detect. To prolong the detection time, gamma-ray emission of molecular clouds produced via proton-proton interactions illuminated by escaped high-energy particles (protons) from the SNR can be used. The talk will report on H.E.S.S. observations of molecular cloud and SNR associations and their possible interpretation.

Speaker: Dr Ira Jung (ECAP, University Erlangen, Germany)

Slides irajung.pdf

107 Disentangling TeV gamma-ray emission in complex regions: the case of the Scutum arm tangent

The HESS Galactic Plane Survey has revealed dozens of large, extended sources. In some regions, especially in the vicinity of Galactic arms tangent points, potential TeV gamma-ray emitters tend to cluster. The TeV gamma-ray source HESS J1843-033 is a large, complex region of emission close to the Scutum arm tangent point. We report detailed analysis of its morphology and identify several independent, discrete sources. We discuss the origin of the TeV gamma-ray emissions in the light of multi-wavelength data, in particular dedicated X-ray observations. We focus on G29.34+0.10, a recently cataloged supernova remnant in spatial coincidence with a large background radio Galaxy

Speaker: Dr Regis Terrier (APC CNRS-Université Paris 7)

Slides Terrier_TevPa.pdf

Particle physics

108 Updated CMB constraints on DM annihilation cross-section

New CMB measurements of the cosmic microwave background anisotropies permit to place strong constraints on the DM annihilation cross section at epochs very close to that of Recombination. Such constraints do not suffer from "systematic astrophysical uncertinties" such as the dependence on the halo shape and concetration, halo minimal mass, depending only on the cosmological parameters. I will discuss this and show the most-up-to date constraints, which already rule-out "thermal" WIMPs with masses below 10 GeV.

Speaker: Fabio Iocco (Institute d'Astrophysique de Paris)

Slides Iocco-CMB-public.pdf

109 Dark Forces at the Tevatron

The anomaly reported recently by CDF can be well fit by a massive Z' coupling primarily to baryons. The U(1) gauge group associated with such a Z' is anomalous in the Standard Model; and so additional particle content is required. In this talk, I discuss two possible UV theories which include a leptophobic Z', and demonstrate that these models generically contain a viable dark matter candidate that have a direct detection cross-sections compatible with the DAMA/Libra and CoGeNT signals. It is therefore possible that collider experiments can directly probe dark forces that connect the Standard Model and the dark sector.

Speaker: Matthew Buckley (Fermilab)

Slides buckley.pdf