Abstract

The red shifted 21-cm emission from neutral hydrogen is a promising tool to unveil the mysteries of the epoch of reionization and cosmic dawn. Ongoing and upcoming experiments such as the GMRT, LOFAR, MWA, SKA are aiming to detect the 21-cm signal statistically through quantities such as the power spectrum, bi-spectrum etc. Recent observations by the EDGES experiment suggest that the intergalactic medium may be much colder during the cosmic dawn than what we expect from the standard cosmological model. The power spectrum and bi-spectrum of the 21-cm signal from reionization and cosmic dawn are expected to different if the intergalactic medium is colder. In this project we wish to explore the impact of the colder intergalactic medium on the power spectrum and bispectrum.