Abstract Details

Name: Pratik Tarafdar
Affiliation: S. N. Bose National Centre for Basic Sciences
Conference ID: ASI2017_1017
Title : Influence of disc geometry on shocked accretion
Authors and Co-Authors : 1. Deepika B. Ananda, Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland. 2. Sankhashubhra Nag, Sarojini Naidu College for Women, Kolkata, India. 3. Tapas Kumar Das, Harish-Chandra Research Institute, Allahabad, India.
Abstract Type : Poster
Abstract Category : General Relativity and Cosmology
Abstract : This work presents a comprehensive and extensive study to illustrate how the geometrical configurations of low angular momentum, axially symmetric, general relativistic matter flow in Schwarzschild and Kerr metric may influence the formation of energy preserving shocks for polytropic accretion, as well as of temperature preserving dissipative shocks for the isothermal accretion, onto non-rotating and rotating astrophysical black holes. The dynamical and thermodynamic states of post-shock polytropic and isothermal flow have been studied extensively for three possible matter geometries, and it has been thoroughly discussed how such states depend on the flow structure, even when the self-gravity and the back-reaction on the metric are not taken into account. We have introduced an eigenvalue based analytical method to qualitatively understand how the phase orbits corresponding to transonic accretion solutions would look like, without incorporating any complicated numerical technique. We have also introduced the concept of quasi-terminal values to understand how the weakly rotating accretion flow behaves at the extreme close proximity of the event horizon and how such behaviours, for different matter geometries, are influenced by the black hole spin. Our main purpose is thus to mathematically demonstrate that for non-self gravitating accretion, various matter geometries, in addition to the corresponding space-time geometry, control the shock induced phenomena as observed within black hole accretion discs. This work is expected to reveal how the shock generated phenomena (emergence of the outflows/flare or the behaviour of QPO of the associated light curves) observed at the close proximity of the horizon depend on the physical environment of the source harbouring a supermassive black hole. It is also expected to unfold the correspondence between dependence of accretion related parameters on flow geometries and the black hole spin.