Séminaire / Seminar GReCO |
| « 21cm fluctuations during the dark ages accounting for the relative velocity of baryons and cdm » |
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Yacine Ali-Haimoud |
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Observations of high-redshift 21cm brightness temperature fluctuations are challenging but can potentially provide unprecedented information about the early universe. In particular, they are the only direct probe of large-scale structure during the cosmic "dark ages", which follow the last scattering of CMB photons and precede the formation of the first luminous objects. During that epoch, the growth of overdensities is very well described by linear perturbation theory and the power spectrum of 21cm fluctuations can in principle be predicted exactly. Recently, Tseliakhovich & Hirata unveiled a previously overlooked physical effect: the suppression of small-scale density fluctuations due to the large relative velocities between baryons and the cold dark matter after recombination. In this talk I will show that this effect significantly impacts the 21cm power spectrum, not only on small-scales but also on large scales due to fluctuations of the relative velocity field on ~ 100 Mpc scales.
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jeudi 7 novembre 2013 - 11:00 Salle des séminaires François Arago Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |