Abstract Details

Name: Ayan Bhattacharjee
Affiliation: S. N. Bose National Centre for Basic Sciences
Conference ID: ASI2020_388
Title : Can the Spectral and Timing Properties of Black Holes and Neutron Stars be Explained by the TCAF Paradigm?
Authors and Co-Authors : Ayan Bhattacharjee^1, Sandip K. Chakrabarti^2 ^1S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata-700106 ^2Indian Centre for Space Physics 43, Chalantika, Garia Station Road, Kolkata- 700084
Abstract Type : Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : Accretion flow around a black hole (BH) or a neutron star (NS) emits high energy radiations with varying spectral and temporal properties. Observed temporal variations point to the existence of a mechanism, dictated by the flow dynamics and not by the stellar surface or magnetic fields, that is common in both types of compact objects. Spectra of multiple sources indicate that the Comptonization process, the dominant mechanism for changing states in X-ray, takes place inside the flow which has similar physical properties in both the objects. The two-component advective flows (TCAF), hitherto applicable only for black holes, satisfy an array of such required properties. This prompted us towards the search for a generalized solution applicable to accretion disks around both BHs and NSs. We show our successful implementation of TCAF solution for BHs where it explains spectral and timing properties self-consistently and provided a well-constrained estimate of the mass of two black holes (persistent Cyg X-1 and transient H1743-322). We show that TCAF, combined with a normal boundary layer (NBOL), explains the spectral features of NSs due to thermal Comptonization. We investigate the inviscid flows with cooling to show that, for wind dominated systems, such as Cir X-1, our solutions are capable of reproducing the observational frequencies of Low-Frequency, hecto-Hz and kilo-Hz QPOs. We show the formation of boundary layers and viscous disks from a sub-Keplerian flow when the viscosity is high. These findings prove the applicability of TCAF formalism to NSs. Finally, we show the formation of TCAF Around NS (TANS). We construct a new spectral model based on TCAF, TANS, which requires 3 additional physical parameters to produce different types (both Z and Atoll) of observed spectra for NSs. This suggests that TANS can be treated as a generalized physical model for BHs and NSs.