Cross-correlating 21cm intensity maps with Lyman Break Galaxies in the post-reionization era

Journal article

We investigate the cross-correlation between the spatial distribution of Lyman Break Galaxies (LBGs) and the 21cm intensity mapping signal at z~[3–5]. At these redshifts, galactic feedback is supposed to only marginally affect the matter power spectrum, and the neutral hydrogen distribution is independently constrained by quasar spectra. Using a high resolution N-body simulation, populated with neutral hydrogen a posteriori, we forecast for the expected LBG-21cm cross-spectrum and its error for a 21cm field observed by the Square Kilometre Array (SKA1-LOW and SKA1-MID), combined with a spectroscopic LBG survey with the same volume. The cross power can be detected with a signal-to-noise ratio (SNR) up to ~10 times higher (and down to ~ 4 times smaller scales) than the 21cm auto-spectrum for this set-up, with the SNR depending only very weakly on redshift and the LBG population. We also show that while both the 21cm auto- and LBG-21cm cross-spectra can be reliably recovered after the cleaning of smooth-spectrum foreground contamination, only the cross-power is robust to problematic non-smooth foregrounds like polarized synchrotron emission.

Authors: Villaescusa-Navarro, F; Viel, M; Alonso, D; Datta, K; Bull, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Journal of Cosmology and Astroparticle Physics
• Volume: 2015
• Issue: 03
• Pages: ARTN 034
• Publication date: 2015-03-18
• Acceptance date: 2015-02-14
• DOI: 10.1088/1475-7516/2015/03/034
• EISSN: 1475-7516
• Keywords: cosmological parameters from LSS; high redshift galaxies; SBTMR; power spectrum