2023PASJ...75...30Y -
Publ. Astron. Soc. Jap., 75, 30-36 (2023/February-0)
X-ray spectroscopy of the accretion disk corona source 2S 0921-630 with Suzaku archival data.
YONEYAMA T. and DOTANI T.
Abstract (from CDS):
2S 0921-630 is an eclipsing low-mass X-ray binary (LMXB) with an orbital period of ∼9 d. Past X-ray observations have revealed that 2S 0921-630 has an extended accretion disk corona (ADC), from which most of the X-rays from the system are emitted. We report the result of our Suzaku archival data analysis of 2S 0921-630. The average X-ray spectrum is reproduced with a blackbody emission (kTbb ∼ 0.3 keV) Comptonized by optically thick gas (“Compton cloud”; optical depth τ ∼ 21) with a temperature of ∼2 keV, combined with 13 emission lines. We find that most of the emission lines correspond to highly ionized atoms: O, Ne, Mg, Si, S, Ar, and Fe. A Kα emission line and an absorption edge of semi-neutral iron (Fe textsci- textscxvii) are also detected. The semi-neutral iron Kα line is significantly broad, with a width of 0.11 ± 0.02 keV in sigma, which corresponds to the Doppler broadening by the Kepler motion at a radius of ∼109 cm. We suggest that the observed semi-neutral iron line originates at the inner part of the accretion disk in the immediate outside of the Compton cloud, i.e., the Compton cloud may have a radius of ∼109 cm.
Abstract Copyright:
© The Author(s) 2022. Published by Oxford University Press on behalf of the Astronomical Society of Japan.
Journal keyword(s):
stars: individual: 2S 0921-630 - stars: neutron - X-rays: stars
Simbad objects:
3
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