Coronal properties of black hole X-ray binaries in the hard state as seen by NuSTAR and Swift

Abstract

In this work, we measure two important phenomenological parameters of corona (and hot accretion flow) in black hole X-ray binaries: the photon index $\Gamma$ and the electron temperature $\te$. Thanks to the capability of {\it NuSTAR} in hard X-rays, we measure these two parameters over six orders of magnitude in the 0.1-100 keV X-ray luminosity $\lx$, from $\sim 5\times10^{38} \ergs$ down to as low as $\sim 5\times10^{32} \ergs$. We confirm the existence of a "V"-shaped correlation between $\Gamma$ and $\lx$. Surprisingly, we observe a "$\Lambda$"-shaped correlation between $\te$ and $\lx$. The "cooler when brighter" branch in the high luminosity regime ($\lx \ga 3\times 10^{36} \ergs$) agrees with previous results and can be understood under the existing model of Compton scattering in the corona. On the other hand, the apparent "cooler when fainter" (positive $\te$-$\lx$ correlation) branch in the low-luminosity regime ($\lx \la 3\times 10^{36} \ergs$) is unexpected, thus it puts a new challenge to existing models of hot accretion flow/corona.

arXiv commentaccepted for publication in ApJL

References in corpus (52)

• On the Absorption of X-rays in the Interstellar Medium
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs
• Hot Accretion Flows Around Black Holes
• Modelling the behaviour of accretion flows in X-ray binaries
• Broad-band gamma-ray and X-ray spectra of NGC 4151 and their implications for physical processes and geometry
• Going with the flow: can the base of jets subsume the role of compact accretion disk coronae?
• A jet model for the broadband spectrum of XTE J1118+480: Synchrotron emission from radio to X-rays in the Low/Hard spectral state
• BlackCAT: A catalogue of stellar-mass black holes in X-ray transients
• A Global Spectral Study of Black Hole X-ray Binaries
• A New Model for Black Hole Soft X-ray Transients in Quiescence
• A Parallax Distance to the Microquasar GRS 1915+105 and a Revised Estimate of its Black Hole Mass
• The Trigonometric Parallax of Cygnus X-1
• Correlations between X-ray and radio spectral properties of accreting black holes
• The first accurate parallax distance to a black hole
• X-ray Reflection Spectroscopy of the Black Hole GX 339-4: Exploring the Hard State with Unprecedented Sensitivity
• The Distance, Inclination, and Spin of the Black Hole Microquasar H1743-322
• The evolution of the high-energy cut-off in the X-Ray spectrum of the GX 339-4 across a hard-to-soft transition
• NuSTAR Spectroscopy of GRS 1915+105: Disk Reflection, Spin, and Connections to Jets
• BAT AGN Spectroscopic Survey -- XII. The relation between coronal properties of Active Galactic Nuclei and the Eddington ratio
• Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation
• The hard X-ray spectral evolution in X-ray binaries and its application to constrain the black hole mass of ultraluminous X-ray sources
• Testing Comptonization models using BeppoSAX observations of Seyfert 1 galaxies
• Gaia DR2 Distances and Peculiar Velocities for Galactic Black Hole Transients
• The mass function of GX 339-4 from spectroscopic observations of its donor star
• Spectral evolution of the microquasar XTE J1550-564 over its entire 2000 outburst
• Broad-band spectra of Cyg X-1 and correlations between spectral characteristics
• Living on a Flare: Relativistic Reflection in V404 Cyg Observed by NuSTAR During its Summer 2015 Outburst
• Study of LINER sources with broad H(alpha) emission. X-ray properties and comparision to luminous AGN and X-ray binaries
• Analysis of NuSTAR and Suzaku observations of Cyg X-1 in the hard state: evidence for a truncated disc geometry
• Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst
• A Model for the Correlation of Hard X-ray Index with Eddington Ratio in Black Hole X-ray Binaries
• The 2015 Decay of the Black Hole X-ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition into Quiescence
• Hard X-ray spectra of AGN in the INTEGRAL complete sample
• Luminous hot accretion flows: the origin of X-ray emission of Seyfert galaxies and black hole binaries
• Luminosity dependence of the electron temperature in the bright hard state of the black hole candidate GX 339--4
• Hard X-ray emission of the microquasar GRO J1655-40 during the rise of its 2005 outburst
• Characterizing X-ray and Radio emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence
• An HI absorption distance to the black hole candidate X-ray binary MAXI J1535-571
• Swift J1357.2-0933: the faintest black hole?
• Accretion Disk Spectra of the Brightest Ultra-luminous X-ray Source in M82
• Detection of X-ray spectral state transitions in mini-outbursts of black hole transient GRS 1739-278
• Swift/XRT- NuSTAR spectra of type 1 AGN]{Swift/XRT- NuSTAR spectra of type 1 AGN: confirming INTEGRAL results on the high energy cut-off
• Monte Carlo simulations of global Compton cooling in inner regions of hot accretion flows
• NuSTAR spectral analysis of two bright Seyfert 1 galaxies: MCG +8-11-11 and NGC 6814
• Jet-dominated quiescent states in black hole X-ray binaries: the case of V404 Cyg
• Study of X-ray variability and coronae of Seyfert galaxies using NuSTAR
• GRS 1739-278 observed at very low luminosity with XMM-Newton and NuSTAR
• The black hole X-ray transient Swift J1357.2-0933 as seen with Swift and NuSTAR during its 2017 outburst
• Thermal Stability of Magnetized, Optically Thin, Radiative Cooling-dominated Accretion Disks
• Bernoulli equation and the nonexistence of maximal jets

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• Possible Coronal Geometry in the Hard and Soft State of Black Hole X-ray Binaries from MONK Simulations