Turbulence and Dynamos

17 March 2008 to 11 April 2008
Nordita
Europe/Stockholm timezone

Scientific programme (17 March - 11 April) and Conference (17-20 March)

Videos: raw data from conference (non-streaming).
Link to streaming video directory (preliminary).

Preliminary Report (draft).

Participation in program and conference is done with the same registration form (see on the left). For the conference the talks will start on Monday, 17 March and will end on Thursday, 20 March. The daily routine follows a similar pattern each day.

       Monday         Tuesday           Wednesday        Thursday

Ge1:           Ge3:              Ga3:               Ga5:
9:00    +++          Marklund          Juvela             Brandenburg
9:30  Leorat         Kleeorin          Vazza              Baggaley
10:00  Sridhar        Tuominen          Waelkens           Korpi
10:30    ***            ***                ***               ***

Ga1:           S2:               Ge5:               Ge7:
11:00  Beck           Tobias            Sur                Shukurov
11:30  Ensslin        Janhunen          Kim                Subramanian
12:30  Haverkorn      Arlt              Frick              Discussion

12:30    $$

S1:            Ga2:              Ge6:
14:00  Hughes         Chyzy             Stepanov           TBA
14:30  Sokoloff       Gaensler          Nazarenko
15:00  Kueker         Fletcher          Kapyla             Gaensler (Colloq
15:30    ***            ***                ***             about SKA)

Ge2:           Ge4:              Ga4:
16:00  Vishniac       Rogachevskii      Bonafede           End of meeting
16:30  Proctor        Yousef/TBA        Yan
17:00  Discussion     Discussion        Discussion
17:30  wine/beer
18:00                                   conf dinner

symbols: *** (coffee), \$ (lunch)


List of conference talks

The conference takes place in the Oscar Klein Auditorium.
When you enter the AlbaNova main building (Roslagstullsback 21),
you are on the 5th floor (because the buidling is on a hillside).
The Klein Auditorium is just down the first stair case (4th floor).

Monday: 17 March

8:30- 9:30 Registration
9:30- 9:25 Jacques Leorat: MHD saturation regime in a Keplerian disk
10:00-10:25 Maarit Korpi: Can MRI be suppressed in galactic disks by SN activity?

10:30-11:00 Coffee

11:00-11:25 Rainer Beck: Magnetic fields in disks and halos of spiral galaxies:
dynamo models confronted with observations
11:30-11:55 Torsten Ensslin: Magnetic turbulence in galaxy clusters
12:00-12:25 Marijke Haverkorn: The Parkes Galactic Meridian Survey:
probing the magnetized halo of the Milky Way

12:30-14:00 Lunch

14:00-14:25 David Hughes: Mean field effects in convective dynamos
14:30-14:55 Dmitry Sokoloff: Low dinensional models of stellar dynamos
15:00-15:25 Manfred Kueker: Magnetic field generation in low-mass stars

15:30-16:00 Coffee

16:00-16:25 Ethan Vishniac: Simulations and theory of nonhelical dynamos
16:30-16:55 Michael Proctor: Effects of fluctuation on alpha-Omega dynamo models
17:00-17:25 Discussion

17:30-19:00 wine/beer

Tuesday: 18 March

9:00- 9:30 Mattias Marklund: Multi-fluids and dynamo theory in general relativity
9:30- 9:25 Nathan Kleeorin: Formation of large-scale inhomogeneous magnetic
structures in a turbulent convection
10:00-10:25 Ilkka Tuominen: Stellar nonlinear dynamos, observations and modelling

10:30-11:00 Coffee

11:00-11:25 Steve Tobias: Turbulent convective dynamos with penetration,
rotation and Shear
11:30-11:55 Pekka Janhunen: The electric sail: a new vehicle in the solar system
12:00-12:25 Rainer Arlt: Magnetic-field generation for Ap stars

12:30-14:00 Lunch

14:00-14:25 Krzysztof Chyzy: Modified and pure dynamo field in nearby galaxies
14:30-14:55 Bryan Gaensler: Revealing cosmic magnetism with radio polarimetry
15:00-15:25 Andrew Fletcher: Observational signatures of dynamo action in
nearby galaxies

15:30-16:00 Coffee

16:00-16:25 Igor Rogachevskii: Generation of large-scale magnetic field in a
sheared non-helical turbulence
16:30-16:55 Tarek Yousef/TBA
17:00-17:25 Discussion

Wednesday: 19 March

9:00- 9:30 Mika Juvela: Simulated observations of turbulent interstellar medium
9:30- 9:25 Franco Vazza: Turbulent field in the intracluster medium of
simulated galaxy clusters
10:00-10:25 Andre Waelkens: Measuring structure in magnetic turbulence by synchrotron
polarimetry: the tension force spectrum from Stokes correlators

10:30-11:00 Coffee

11:00-11:25 Sharanya Sur: Kinetic and magnetic alpha-effects in mean-field dynamos
11:30-11:55 Eun-jin Kim: Theory of turbulent transport and dynamos in astrophysical plasmas
12:00-12:25 Peter Frick: Forced MHD-turbulence in presence of cross-helicity

12:30-14:00 Lunch

14:00-14:25 Rodion Stepanov: Saturation scenario for the turbulent dynamo
14:30-14:55 Sergey Nazarenko: Finite-box effects in MHD turbulence
15:00-15:25 Petri Käpylä: Dynamos with fractional helicity

15:30-16:00 Coffee

16:00-16:25 Annalisa Bonafede: The Coma cluster magnetic field from Faraday rotation measures
16:30-16:55 Huirong Yan: Studies of magnetic field with aligned atoms
17:00-17:25 Discussion

18:30-21:00: Conference dinner

Thursday: 20 March

9:00- 9:30 Axel Brandenburg: Incoherent alpha versus shear-current effects
9:30- 9:25 Andrew Baggaley: A new approach to flux rope dynamos
10:00-10:25 S. Sridhar: Imbalanced Strong MHD Turbulence

10:30-11:00 Coffee

11:00-11:25 Anvar Shukurov: Magnetic structures produced by the fluctuation dynamo
11:30-11:55 Kandaswamy Subramanian: Magnetic helicity density and its flux
12:00-12:25 Discussion

12:30-14:00 Lunch

14:00-15:00 TBA
15:00-15:15 Coffee
15:15-16:15 Bryan Gaensler:  Overview talk on the Square Kilometer Array

16:25 End of conference; continue programme activity in the Nordita Building

The Nordita Building (Roslagstullsback 23) is located on the right just
outside the AlbaNova main building.


Organisers

A. Shukurov (anvar.shukurov@ncl.ac.uk), K. Subramanian (kandu@iucaa.ernet.in), A. Brandenburg (brandenb@nordita.org), M. J. Korpi (maarit.korpi@helsinki.fi)

Background

The origin of astrophysical magnetic fields remains controversial. It is more or less generally accepted that they are most often produced and then supported by some form of a self-sustained dynamo action, that is, by conversion of kinetic energy of a plasma flow into magnetic energy. It has been proved that the motions involved must be three-dimensional (Cowling's and Zeldovich's theorems), so simple low-dimensional models are of limited value. Furthermore, both non-chaotic and non-random flows can only produce the so-called slow dynamos, where the growth rate of the magnetic field tends to zero for large magnetic Reynolds numbers typical of astrophysical environments. Since virtually any chaotic or random astrophysical flow becomes turbulent because of the large Reynolds number, astrophysical dynamos usually are turbulent dynamos.

Aims and Scope

The intense progress in nonlinear and turbulent dynamo theory of the last ten years has prepared ground for imminent fundamental progress in this area. Much has recently been understood from numerical simulations and analytical efforts. Useful, albeit non-universal approximations for the mean-field theory applicable in a broad range of parameters have been developed, and techniques for incorporating magnetic helicity conservation into dynamo models are being developed. Observational data from galaxies and galaxy clusters are now becoming better suitable for studies of the interstellar and intracluster turbulence. The programme will bring together experts in various relevant areas in order to (1) identify the critical problems to allow further rapid progress, (2) focus the effort on the most fruitful areas of research and (3) establish new collaborations, especially those between theoreticians and observers, that might ensure such a progress. In particular, interstellar and intracluster plasmas appear to be an excellent laboratory to study turbulent dynamos, especially because of the available abundance (and further rapid growth of the quality and quantity) of observational data. Some of key problems are:

Saturation mechanisms of the small-scale dynamo; spectra of resulting magnetic fields.

The role of plasma effects in interstellar and intracluster dynamos.

Mechanisms of saturation of mean-field dynamos: helicity conservation and Lagrangian chaos.

Alfv\'en-wave turbulence, wave-wave interactions and MHD turbulence spectra; relation between dynamo mechanisms (producing nonlocal interactions in the wavenumber space) and turbulent cascades.

Interpretation and significance of numerical dynamo simulations.

The significance of various mean-field effects in stars and galaxies.

Turbulent closure models and dynamo theory.

Recent observational results on galactic and intracluster magnetic fields and their interpretation; the origin and sources of intracluster turbulence: galactic wakes versus merger events.

The structure of the program

The program will start with a one-week conference in order to highlight the most recent results, identify common interests and initiate discussions. This meeting may attract a much broader audience than the long-term participants alone (about 50 participants in total).

Two general discussions per week will be organised, on topics listed above, each facilitated by two mediators appointed in advance.

Regular seminars (about 1 hour long), in particular presented by those participants who were unable to present a talk at the start-off conference. How to get here? (this link has a description and a map). The meeting takes place in the Nordita building, just next to the AlbaNova main building.

The meeting is sponsored jointly by Nordita, the Swedish Research Council, and the AstroSim programme.

Starts
Ends
Europe/Stockholm
Nordita
Roslagstullsbacken 23 AlbaNova University Center 10691 Stockholm Sweden
 Participants and timetable
Further details will be published as soon as available. If you are interested in participating in any part of the programme, please register via the programme web page.