2017/11/13 by Yanjun Xu, Javier A. García, Javier A. Garcia +10 · 21 citations
Physics and Astronomy · #Accretion (finance) #Accretion disc #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Black hole (networking) #Pulsars and Gravitational Waves Research #Reflection (computer programming) #Spectral analysis #Spectral density #Spectral line #Spectral shape analysis #astro-ph.HE
paper · pdf · doi:10.3847/1538-4357/aa9ab4
published in The Astrophysical Journal 851(2), 103 (IOP Publishing) · 11 pages, 9 figures, accepted by ApJ
arxiv created 2017/11/13 · openalex created_date 2017/12/04 · openalex publication_date 2017/12/18 · arxiv updated 2017/12/27 · openalex updated_date 2026/08/06
Abstract We present a spectral and timing study of the NuSTAR and Swift observations of the black hole candidate IGR J17091–3624 in the hard state during its outburst in 2016. Disk reflection is detected in each of the NuSTAR spectra taken in three epochs. Fitting with relativistic reflection models reveals that the accretion disk is truncated during all epochs with , with the data favoring a low disk inclination of ∼30°–40°. The steepening of the continuum spectra between epochs is accompanied by a decrease in the high energy cutoff: the electron temperature drops from ∼64 to ∼26 keV, changing systematically with the source flux. We detect type-C QPOs in the power spectra with frequency varying between 0.131 and 0.327 Hz. In addition, a secondary peak is found in the power spectra centered at about 2.3 times the QPO frequency during all three epochs. The nature of this secondary frequency is uncertain; however, a non-harmonic origin is favored. We investigate the evolution of the timing and spectral properties during the rising phase of the outburst and discuss their physical implications.