Spectral and Timing Properties of IGR J17091-3624 in the Rising Hard State During its 2016 Outburst

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 $R_{\mathrm{in}}>10r_{\mathrm{g}}$, with the data favoring a low disk inclination of $\sim 30^{\circ }-40^{\circ }$. The steepening of the continuum spectra between epochs is accompanied by a decrease in the high energy cut-off: the electron temperature $k{T}_{\mathrm{e}}$ drops from $\sim 64$ keV to $\sim 26$ keV, changing systematically with the source flux. We detect type-C QPOs in the power spectra with frequency varying between 0.131 Hz 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.

11 pages, 9 figures, accepted by ApJ

References in corpus (9)

• X-ray Properties of Black-Hole Binaries
• The role of the reflection fraction in constraining black hole spin
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• On the Bardeen-Petterson Effect in black hole accretion discs
• No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR
• Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst
• Phase-resolved spectroscopy of low frequency quasi-periodic oscillations in GRS 1915+105
• New Constraints on the Black Hole Low/Hard State Inner Accretion Flow with NuSTAR
• Solutions to the relativistic precession model

Cited by in corpus (10)

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• Studying the Reflection Spectra of the New Black Hole X-ray Binary Candidate MAXI J1631-479 Observed by NuSTAR: A Variable Broad Iron Line Profile
• NuSTAR observations of the Transient Galactic Black Hole Binary Candidate Swift J1858.6-0814: A New Sibling of V404 Cyg and V4641 Sgr?
• The current state of disk wind observations in BHLMXBs through X-ray absorption lines in the iron band
• Evidence for Disk Truncation at Low Accretion States of the Black Hole Binary MAXI J1820+070 Observed by NuSTAR and XMM-Newton
• High-density reflection spectroscopy of black hole X-ray binaries in the hard state
• A Machine Learning approach for classification of accretion states of Black hole binaries
• Simultaneous detection of an intrinsic absorber and a compact jet emission in the X-ray binary IGR J17091-3624 during a hard accretion state
• X-ray spectral correlations in a sample of Low-mass black hole X-ray binaries in the hard state
• Swift/XRT, Chandra and XMM-Newton observations of IGR J17091-3624 as it returns into quiescence