Neutral hydrogen at high redshifts as a probe of structure formation

Abstract

Structure formation at z≲ 10.0 can be detected and studied using the 21 cm line emission from the neutral hydrogen. Two of us (Suramanian & Padmanabhan 1993, Paper I) had earlier computed the expected abundance of Procrustes as a function of the flux density a function of the flux density at various redshifts, in the detail how the HI line profile from a single spherically symmetric protocluster evolves as it decouples from hubble expansion and colapses. We find peak fluxes of the HI line profile to be typically of order 0.4-0.8 mJy while the widths (FWHM) are of order 0.6-1.5 Mhz. Such protoclusters could be detectable by the Giant Metrewave Radio Telescope (GMRT) which is being built in India.