A year in the life of the low-mass X-ray transient Aql X-1
Abstract
The Swift satellite monitored the quiescence of the low-mass X-ray binary transient Aql X-1 on a weekly basis during the 2012 March-November interval. A total of 42 observations were carried out in the soft X-ray (0.3-10 keV) band with the X-ray telescope on board Swift. We investigated the X-ray variability properties of Aql X-1 during quiescence by tracking luminosity variations and characterizing them with a detailed spectral analysis. The source is highly variable in this phase and two bright flares were detected, with peak luminosities of ∼4 × 1034 erg s- 1 (0.3-10 keV). Quiescent X-ray spectra require both a soft thermal component below ∼2 keV and a hard component (a power-law tail) above ∼2 keV. Changes in the power-law normalization alone can account for the overall observed variability. Therefore, based on our data set, the quiescent X-ray emission of Aql X-1 is consistent with the cooling of the neutron star core and with mechanisms involving the accretion of matter on to the neutron star surface or magnetosphere.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2014
- DOI:
- 10.1093/mnras/stt2384
- arXiv:
- arXiv:1312.2379
- Bibcode:
- 2014MNRAS.438.2634C
- Keywords:
-
- accretion;
- accretion discs;
- binaries: close;
- stars: neutron;
- stars: individual: Aql X-1;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 7 figures, 4 tables