Probing the Epoch of Reionization with the 21 cm emission
Benoit SEMELIN
Observatoire de Paris/LERMA & Paris VI
Résumé :
In the next decade the Square Kilometer Array and its pathfinders
(LOFAR, MWA, etc...) will be able to observe the 21cm radiation
emitted by neutral hydrogen during the Epoch of Reionization.
These observations will teach us a lot about the nature and formation
history of the first sources of light, and will yield constaints on
cosmological models.To be able to optimize the instrument design and
interpret the future observations, we need an accurate modeling of
the 21cm signal.
I will first present the physics of the 21 cm emission and the prospects
for detections by the future radio-interferometers. Then I will explain
how the nature of the sources (Pop III stars, Pop II stars, QSO,
Supernovae, X-ray binaries) and the state of the Inter-Galactic Medium
can alter the statistical properties of the signal.
In the framework of the SKA Design Study, we have performed
hydrodynamical and radiative transfer simulations in a cosmological
context to predict the 21cm signal. We have included
physical processes that have been neglected until now. Indeed, in
addition to the ionizing radiation, we compute the full 3D radiative
transfer for the Lyman-alpha photons, which is necessary to compute
correctly the 21-cm brightness temperature. The effect of Lyman-alpha
photons is especially important during the early absorption phase
and/or if the sources have a soft spectrum (Pop II and Pop III stars).
I will present emission maps and power spectra for the signal and
derive tentative suggestions for the design of the future instruments.
