The cross-correlation of the CMB polarization and the 21-cm line fluctuations from cosmic reionization |
| |
| Authors: | Hiroyuki Tashiro Nabila Aghanim Mathieu Langer Marian Douspis Saleem Zaroubi |
| |
| Institution: | Institut d'Astrophysique Spatiale (IAS), Bâtiment 121, F-91405, Orsay, France;UniversitéParis-Sud XI and CNRS (UMR 8617), France;Kapteyn Astronomical Institute, Landleven 12, Groningen 9747 AD, the Netherlands |
| |
| Abstract: | The cosmic microwave background (CMB) polarization and the 21-cm line fluctuations are powerful probes of cosmological reionization. We study how the cross-correlation between the CMB polarization ( E modes) and the 21-cm line fluctuations can be used to gain further understanding of the reionization history, within the framework of inhomogeneous reionization. Since the E -mode polarization reflects the amplitude of the quadrupole component of the CMB temperature fluctuations, the angular power spectrum of the cross-correlation exhibits oscillations at all multipoles. The first peak of the power spectrum appears at the scale corresponding to the quadrupole at the redshift, which is probed by the 21-cm line fluctuations. The peak reaches its maximum value in redshift when the average ionization fraction of the universe is about half. On the other hand, on small scales, there is a damping that depends on the duration of reionization. Thus, the cross-correlation between the CMB polarization and the 21-cm line fluctuations has the potential to accurately constrain the epoch and the duration of reionization. |
| |
| Keywords: | cosmology: theory large-scale structure of Universe |
|
|
