Probing the primordial universe with electromagnetic and gravitational waves
ABSTRACT :
Over the last half-a-century or so, the observations of the cosmic microwave background (CMB) have provided us with clues to the physics operating in the early universe. During the past decade, the detection of gravitational w aves (GWs) from merging compact binaries by the Laser Interferometer Gravitational-Wave Observatory has opened up a new window to observe our universe. In this talk, I will initially describe the physics of inflation that is supposed to be responsible for the generation of the primordial perturbations and the constraints on inflation from the CMB. Thereafter, I will describe the manner in which the dynamics during the later stages of inflation and the phase of reheating (which connects the epochs of inflation and radiation domination) can lead to the generation of primordial GWs of strengths detectable by the ongoing and forthcoming GW observatories. I will conclude the talk with a discussion on the recent observations by the pulsar timing arrays that point to a stochastic background of GWs and the possible implications of the observations for the physics of the primordial universe.
ABOUT THE SPEAKER:
L. Sriramkumar is a Professor of Physics at the Indian Institute of Technology (IIT) Madras, Chennai. He completed his doctoral thesis under the supervision of Prof. Thanu Padmanabhan at the Inter-University Centre for Astronomy and Astrophysics, Pune, in 1997. He worked as a postdoctoral fellow under the mentorship of Prof. Jacob Beke nstein (at the Racah Institute of Physics, Hebrew University, Jerusalem, Israel) and Prof. Don Page (at the Department of Physics, University of Alberta, Edmonton, Canada) during 1997-99 and 1999-2001, before joining the Harish-Chandra Research Institute, Prayagraj, initially as a post-doctoral fellow in 2001, and then as a faculty in 2003. He moved to the IIT Madras in 2011. Prof. Sriramkumar has worked on various aspects of gravitation and cosmology, and his recent research has been focused on the physics of the early universe.