Radiative cooling and state transition in stellar mass black holes.

Author(s)

Artur Vemado

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Astronômico e Geofísico (IAG/SBD)
• Defense date: 2020-04-13

Examining board members

Rodrigo Nemmen da Silva; Javier Garcia; Raimundo Lopes de Oliveira Filho; Elisabete Maria de Gouveia Dal Pino

• Advisor: Rodrigo Nemmen da Silva

Abstract

Black hole (BH) X-ray binaries are characterized by different spectral states along their lives. These states can be explained by the presence of a hot, geometrically thick corona for the hard state and a colder thin disk for the soft state. However, the degree to which the hot corona and the thin accretion disk coexist is not well understood. In particular, it is unclear how the inner radius of the thin disk and the properties of the hot corona (e.g. size and temperature) are related to the fundamental system properties such as the BH mass accretion rate M. In this work, two-dimensional hydrodynamical simulations with radiative cooling of accretion flows around stellar black holes were performed to investigate the interplay between the thin disk and hot corona and the relation between the truncation radius R tr and M. The contribution of Bremsstrahlung, synchrotron and comptonized synchrotron cooling processes were incorporated in the energy equation. The main results of this work are (i) the new relation R tr m -1/2 connecting two basic properties of accreting BHs and (ii) the decrease of both temperature and spatial extent of the corona with increasing M. These results are expected to shed light on observations of BH binaries. (AU)

• FAPESP's process: 17/25710-1 - Radiative cooling in black hole accretion flows
• Grantee: Artur Vemado
• Support Opportunities: Scholarships in Brazil - Master