Monte Carlo simulations of thermal comptonization process in a two-component advective flow around a neutron star
Abstract
We explore spectral properties of a two-component advective flow around a neutron star. We compute the effects of thermal Comptonization of soft photons emitted from a Keplerian disc and the boundary layer of the neutron star by the post-shock region of a sub-Keplerian flow, formed due to the centrifugal barrier. The shock location Xs is also the inner edge of the Keplerian disc. We compute a series of realistic spectra assuming a set of electron temperatures of the post-shock region TCE, the temperature of the Normal BOundary Layer (NBOL) TNS of the neutron star and the shock location Xs. These parameters depend on the disc and halo accretion rates (\dot{m}d and \dot{m}h, respectively) that control the resultant spectra. We find that the spectrum becomes harder when \dot{m}_h is increased. The spectrum is controlled strongly by TNS due to its proximity to the Comptonizing cloud since photons emitted from the NBOL cool down the post-shock region very effectively. We also show the evidence of spectral hardening as the inclination angle of the disc is increased.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2017
- DOI:
- 10.1093/mnras/stx1867
- arXiv:
- arXiv:1901.00842
- Bibcode:
- 2017MNRAS.472.1361B
- Keywords:
-
- accretion;
- accretion discs;
- radiation: dynamics;
- scattering;
- shock waves;
- stars: neutron;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 28 pages, 14 figures, 1 table