MOSIR Project

Atomic Hydrogen in the Universe (1/2)

Speaker	Jayaram Chengalur (NCRA/TIFR, India)
Date	2011/09/26 - 2011/10/01
Seminar	JSPS-DST Asia Academic Seminar / CPS 8th International School of Planetary Sciences

Place	Minami-Awaji Royal Hotel, Minamiawaji, Hyogo, Japan
Documents	Presentation (11.61MB)

Abstract	Atomic hydrogen’s (HI) spectral line at rest wavelength of 21cm is by far the most widely observed line at low radio frequencies. The bulk of the observations are of gas in galaxies at essentially zero redshift, where the line in an important tracer of the dynamics of galaxies. Observations of the average HI content of galaxies at redshifts between 0-1 give important information on the evolution of the gas content of galaxies. HI absorption has been observed in Damped Lyman-alpha systems with redshifts as high as 3. In these systems HI is a useful tracer of the dynamics of the systems, as well as carrying information on the physical conditions in the absorber. Finally there are several on going eﬀorts to try and detect the 21cm emission from HI at the epoch of recombination. In this lecture I will discuss the HI observations at a range of diﬀerent redshifts.
Keywords	atomic hydrogen, HI, galaxy, observation, redshift, lyman-alpha