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

Journal article

Publication Details

Author(s): Kalemci E, Arabaci MO, Guver T, Russell DM, Tomsick JA, Wilms J, Weidenspointner G, Kuulkers E, Falanga M, Dincer T, Drave S, Belloni T, Coriat M, Lewis F, Munoz-Darias T
Journal: Monthly Notices of the Royal Astronomical Society
Publication year: 2014
Volume: 445
Journal issue: 2
Pages range: 1288-1298
ISSN: 0035-8711
eISSN: 1365-2966


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.

FAU Authors / FAU Editors

Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

External institutions with authors

European Space Agency (ESA)
European X-Ray Free-Electron Laser Facility GmbH
International Space Science Institute (ISSI)
Istanbul University / İstanbul Üniversitesi
Middle East Technical University (METU) / Orta Doğu Teknik Üniversitesi
National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF)
New York University Abu Dhabi (NYU Abu Dhabi)
Sabanci University
University of California, Berkeley
University of Cape Town (UCT)
University of Oxford
University of Southampton
University of South Wales

How to cite

Kalemci, E., Arabaci, M.O., Guver, T., Russell, D.M., Tomsick, J.A., Wilms, J.,... Munoz-Darias, T. (2014). Multiwavelength observations of the black hole transient Swift J1745-26 during the outburst decay. Monthly Notices of the Royal Astronomical Society, 445(2), 1288-1298.

Kalemci, E., et al. "Multiwavelength observations of the black hole transient Swift J1745-26 during the outburst decay." Monthly Notices of the Royal Astronomical Society 445.2 (2014): 1288-1298.


Last updated on 2019-26-07 at 09:33