BeppoSAX observation of the eclipsing dipping X-ray binary X 1658-298
Abstract
Results of a 2000 August 12-13 BeppoSAX observation of the 7.1 hr eclipsing, dipping, bursting, transient, low-mass X-ray binary (LMXRB) s-1rc are presented. The spectrum outside of eclipses, dips and bursts can be modeled by the combination of a soft disk-blackbody and a harder Comptonized component with a small amount (1.3 x 1021 atom cm-2) of low-energy absorption. In contrast, an RXTE observation 18 months earlier during the same outburst, measured an absorption of 5.0 x 1022 atom cm-2. Such a change is consistent with a thinning of the accretion disk as the outburst progresses. Structured residuals from the best-fit spectral model are present which are tentatively identified with Ne-K/Fe-L and Fe-K shell emission. The spectral changes during dips are complex and may be modeled by a strong (~3 x 1023 atom cm-2) increase in absorption of the Comptonized component only, together with reductions in normalizations of both spectral components. This behavior is in contrast to the ``complex continuum'' model for X-ray dip sources, where the softer blackbody component rapidly suffers strong absorption. It is however, similar to that found during recent XMM-Newton observations of the eclipsing, dipping, LMXRB EXO 0748-676. An updated orbital ephemeris is provided which does not require a quadratic term, in contrast to that of Wachter et al. (\cite{w:00}).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 2001
- DOI:
- 10.1051/0004-6361:20011006
- arXiv:
- arXiv:astro-ph/0107338
- Bibcode:
- 2001A&A...376..532O
- Keywords:
-
- ACCRETION;
- ACCRETION DISKS;
- STARS: INDIVIDUAL: X 1658-298;
- STARS: NEUTRON;
- X-RAYS: STARS;
- Astrophysics
- E-Print:
- 11 pages. Accepted for publication in A&