The sources of cosmic reionisation

by Dr Jan-Pieter Paardekooper (Max Planck Institute for Extraterrestrial Physics)

Monday 18 Nov 2013, 11:15 → 12:00 Europe/Stockholm

FA31

The formation of the first stars and galaxies marks the beginning of the Epoch of Reionisation, when the inter-galactic gas was transformed from cold and neutral to a hot, ionised plasma. The coming years promise to be very exciting for the study of reionisation as newly build low-frequency radio arrays like LOFAR will likely detect the 21 cm signal of neutral hydrogen during this important epoch. For the interpretation of this signal numerical simulations are vital but these are extremely challenging due to the large simulation volumes that are required. These simulations therefore rely heavily on the source models used. My work aims to test these assumptions by simulating the sources of reionisation at high resolution taking into account the relevant baryonic processes. Using high-resolution simulations of isolated galaxies and a large sample of galaxies from cosmological galaxy formation simulations I will show which physical processes drive the escape of ionising photons from galaxies and how this depends on the properties of the halo in which galaxies are forming. Our simulations show that the source models in large-scale reionisation simulations are inaccurate and that reionisation could progress markedly different from what simulations have shown so far.