Study of the reflection spectra of SAX J1748.9-2021
Abstract
We report the spectral analysis of accretion powered millisecond X-ray pulsar SAX J1748.9-2021 from the NuSTAR observation made during its 2015 outburst. The spectra displayed a broad emission line at ∼6.5 keV with line width of ∼0.5 keV and excess above ∼20 keV due to Compton hump. The persistent emission of SAX J1748.9-2021 is described by a combination of soft thermal component with kT =0.62^{+0.03}_{-0.05} keV and thermally Comptonized component with kT_e=2.50^{+0.06}_{-0.03} keV reflected from the disc with reflection fraction of 0.30^{+0.08}_{-0.04}. We have modelled the reflection spectrum with self-consistent model relxillCP and have found the inclination of the accretion disc to be 32.3°+4.8-4.7 and log ξ is equal to 3.05^{+0.40}_{-0.34}. We have obtained an upper limit of 57 km for inner disc radius; and the estimated magnetic field strength at the poles is less than 3.4 × 109 G. This kind of detailed investigation of reflection spectrum of SAX J1748.9-2021, especially above 10 keV, has been achieved only because of high statistics NuSTAR data of the source.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2019
- DOI:
- 10.1093/mnras/sty2808
- arXiv:
- arXiv:1810.07115
- Bibcode:
- 2019MNRAS.482.1634S
- Keywords:
-
- accretion;
- accretion discs;
- stars: neutron;
- X-rays: binaries;
- X-rays: individual: SAX J1748.9-2021;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 6 pages, 6 figures. Accepted for publication in MNRAS