Accueil > Séminaires d’Astrophysique > Using the 21 cm emission to study the Epoch of Reionization with SKA


Using the 21 cm emission to study the Epoch of Reionization with SKA

Benoît Semelin (LERMA)

Par Stephane Charpinet - 25/02/2009


Séminaires d’Astrophysique

de l’Observatoire Midi-Pyrénées

Séminaire de



Jeudi 26 Février 2009 à 11h

OMP, salle Jules Verne

Using the 21 cm emission to study the Epoch of Reionization with SKA

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 acurate 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 Lyman-alpha photons are 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.



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