Multiwavelength observations of the black hole transient Swift J1745-26 during the outburst decay

Kalemci E., Arabaci M. O. , Guver T. , Russell D. M. , Tomsick J. A. , Wilms J., ...Daha Fazla

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, cilt.445, ss.1288-1298, 2014 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 445 Konu: 2
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1093/mnras/stu1851
  • Sayfa Sayıları: ss.1288-1298


We characterized the broad-band X-ray spectra of Swift J1745-26 during the decay of the 2013 outburst using INTEGRAL ISGRI, JEM-X and Swift XRT. The X-ray evolution is compared to the evolution in optical and radio. We fit the X-ray spectra with phenomenological and Comptonization models. We discuss possible scenarios for the physical origin of an similar to 50 d flare observed both in optical and X-rays similar to 170 d after the peak of the outburst. We conclude that it is a result of enhanced mass accretion in response to an earlier heating event. We characterized the evolution in the hard-X-ray band and showed that for the joint ISGRI-XRT fits, the e-folding energy decreased from 350 to 130 keV, while the energy where the exponential cut-off starts increased from 75 to 112 keV as the decay progressed. We investigated the claim that high-energy cut-offs disappear with the compact jet turning on during outburst decays, and showed that spectra taken with HEXTE on RXTE provide insufficient quality to characterize cut-offs during the decay for typical hard-X-ray fluxes. Long INTEGRAL monitoring observations are required to understand the relation between the compact jet formation and hard-X-ray behaviour. We found that for the entire decay (including the flare), the X-ray spectra are consistent with thermal Comptonization, but a jet synchrotron origin cannot be ruled out.