A year in the life of the low-mass X-ray transient Aql X-1

作者：Zelati F Coti^*; Campana S; D'Avanzo P; Melandri A

来源：Monthly Notices of the Royal Astronomical Society, 2014, 438(3): 2634-2641.

DOI：10.1093/mnras/stt2384

• accretion
• accretion discs
• binaries: close
• stars: neutron
• stars: individual: Aql X-1
• X-rays: binaries

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 similar to 4 x 10(34) erg s(- 1) (0.3-10 keV). Quiescent X-ray spectra require both a soft thermal component below similar to 2 keV and a hard component (a power-law tail) above similar to 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.

• 出版日期2014-3