J N Chengalur

TIFR, Mumbai

Jayaram N. Chengalur obtained his B.Tech. in Electrical Engineering from IIT-Kanpur in 1987. He then moved to Cornell University for his doctoral studies, completing his PhD in 1994. Following this, he worked as a post-doctoral fellow at the Netherlands Institute for Radio Astronomy (ASTRON) in the Netherlands, before joining the National Centre for Radio Astrophysics in 1996. He is a Fellow of the Indian Academy of Sciences (2011), the National Academy of Sciences, India, and the Indian National Science Academy. His main research focus is in extragalactic astronomy, particularly studies of nearby dwarf irregular galaxies, neutral hydrogen (HI) absorption in very high redshift galaxies (the so-called “damped Lyman alpha” systems), and in general studies of the evolution of the neutral hydrogen content of the universe.

J N Chengalur

Session 2A: Special Lecture

G C Anupama, Bengaluru

Gas and Galaxy Evolution

As galaxies evolve, they convert their gas into stars. On a cosmic scale, it is well established that star formation peaked at about 10 billion years ago (redshifts  2–3) and the average star-formation rate of the Universe has declined sharply since then. Atomic hydrogen is the primary fuel for star formation. Stars form as gas cools to become molecular hydrogen, and then cools further and collapses under self-gravity. Hence, understanding the evolution of atomic hydrogen content of galaxies is the key to understand the evolution of star-formation rate with cosmic time. Unfortunately, because of the difficulties in detecting atomic hydrogen emission (via its best tracer, the 21-cm spectral line), until recently, very little was known about the evolution of gas content of star-forming galaxies. In this talk, the results from the ongoing atomic hydrogen surveys of star-forming galaxies using the upgraded GiantMeterwave Radio Telescope will be presented. These have significantly added to our understanding of the evolution of the baryon content of galaxies.