Neutral hydrogen at high redshifts as a probe of structure formation - III. Radio maps from N-Body simulations

Abstract

Large inhomogeneities in neutral hydrogen in the universe can be detected at redshifts $z \leq 10$ using the redshifted 21 cm line emission. We use cosmological N-Body simulations for dark matter and a simple model for baryonic collapse to estimate the signal expected from structures like proto-clusters of galaxies at high redshifts. We study: (i) the standard CDM model, (ii) a modified CDM model with less power at small scales, and (iii) a $\Lambda+$CDM model in a universe with $\Omega_0 + \Omega_\Lambda = 1$. We show that it should be possible for the next generation radio telescopes to detect such structures at the redshift 3.34 with an integration of about 100 hours. We also discuss possible schemes for enhancing signal to noise ratio to detect proto-condensates at high redshifts.