PROFESSOR BARUN DHAR

It is nearly 80 years now since the first model of distribution of stars in a galaxy was proposed and 25 years of high resolution data from the Hubble Space Telescope. Yet, the answer to the questions – i) what model best describes this distribution; and ii) is there a universal function describing all galaxies – remain elusive till date. In this talk, the speaker will discuss possible answers to these two questions. While the talk will focus on the most evolved galaxies -- the ellipticals -- the methodology can be extended to spirals as well. In the first part of the talk he will show how we can model a wide range of elliptical galaxies (from dwarfs to the massive ellipticals) to an unprecedented level (~3% errors over large dynamic ranges). In the second part, he will highlight new insights we get on the internal structure of galaxies from such high precision modeling. For instance, it is widely believed that massive galaxies have a mass-deficit in the central regions due to scouring by the super-massive blackhole at the center. We will see if this interpretation of mass-deficit still holds when we successfully model galaxies with such high precision.