2007/12/31 by Liron Gleser, Adi Nusser, Andrew J. Benson · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.13897.x
published as 2008MNRAS.391..383G · 19 pages, 17 figures, accepted for publication in MNRAS
arxiv created 2008/10/27 · arxiv updated 2009/12/01
We present a method for extracting the expected cosmological 21-cm signal from the epoch of reionization, taking into account contaminating radiations and random instrumental noise. The method is based on the maximum a-posteriori probability (MAP) formalism and employs the coherence of the contaminating radiation along the line-of-sight and the three-dimensional correlations of the cosmological signal. We test the method using a detailed and comprehensive modeling of the cosmological 21-cm signal and the contaminating radiation. The signal is obtained using a high resolution N-body simulation where the gas is assumed to trace the dark matter and is reionized by stellar radiation computed from semi-analytic galaxy formation recipes. We model contaminations to the cosmological signal from synchrotron and free-free galactic foregrounds and extragalactic sources including active galactic nuclei, radio haloes and relics, synchrotron and free-free emission from star forming galaxies, and free-free emission from dark matter haloes and the intergalactic medium. We provide tests of the reconstruction method for several rms values of instrumental noise from σN=1 to 250 mK. For low instrumental noise, the recovered signal, along individual lines-of-sight, fits the true cosmological signal with a mean rms difference of drms≈ 1.7± 0.6 for σN=1 mK, and drms≈ 4.2± 0.4 for σN=5 mK. The one-dimensional power spectrum is nicely reconstructed for all values of σN considered here, while the reconstruction of the two-dimensional power spectrum and the Minkowski functionals is good only for noise levels of the order of few mK.