Analysis of NuSTAR and Suzaku observations of Cyg X-1 in the hard state: evidence for a truncated disc geometry

Abstract

The geometry of the accretion flow in black-hole X-ray binaries in the hard state, in particular the position of the disc inner edge, has been a subject of intense debate in recent years. We address this issue by performing a spectral study of simultaneous observations of Cyg X-1 in the hard state by NuSTAR and Suzaku. The same data were analysed before, and modelled by a lamppost containing hybrid electrons and located very close to the horizon, which emission was incident on a surrounding disc extending almost to the innermost stable circular orbit. We re-analyse the incident continuum model and show that it suffers from the lack of physical self-consistency. Still, the good fit to the data provided by this model indicates that the real continuum has a similar shape. We find it features a strong soft X-ray excess below a few keV, which we model as a soft thermal-Comptonization component, in addition to the main hard thermal-Compton component. This continuum model with reflection of both components yields the overall lowest ${\chi }^2$ and has a geometry with a hot inner accretion flow and a disc truncated at $\simeq$13--20 gravitational radii. On the other hand, we have also found spectral solution with a lamppost at a large height and a disc that can extend to the innnermost stable circular orbit, though somewhat statistically worse. Overall, we find the fitted truncation radius depends on the assumed continuum and geometry.

MNRAS, in press

References in corpus (75)

• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• 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
• Improved Reflection Models of Black-Hole Accretion Disks: Treating the Angular Distribution of X-rays
• Hard X-ray Detector (HXD) on Board Suzaku
• Radiation mechanisms and geometry of Cygnus X-1 in the soft state
• Low frequency QPO spectra and Lense-Thirring precession
• The Two-Phase Pair Corona Model for Active Galactic Nuclei and X-ray Binaries: How to Obtain Exact Solutions
• The Spectrum of Diffuse Cosmic Hard X-Rays Measured with HEAO-1
• On the X-ray time lags in the black hole candidates
• The Mass of the Black Hole in Cygnus X-1
• X-ray reflected spectra from accretion disk models. I. Constant density atmospheres
• Broad emission lines for negatively spinning black holes
• Radiative Processes, Spectral States and Variability of Black-Hole Binaries
• Correlation between Compton reflection and X-ray slope in Seyferts and X-ray binaries
• Calibration of the NuSTAR High Energy Focusing X-ray Telescope
• Simultaneous X-ray and gamma-ray observations of Cyg X-1 in the hard state by Ginga and OSSE
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• The Extreme Spin of the Black Hole in Cygnus X-1
• The Soft Gamma-Ray Spectral Variability of Cygnus X-1
• A physical model for the continuum variability and QPO in accreting black holes
• The Trigonometric Parallax of Cygnus X-1
• Correlations between X-ray and radio spectral properties of accreting black holes
• Black hole accretion disks in the canonical low-hard state
• X-ray irradiation in XTE J1817-330 and the inner radius of the truncated disc in the hard state
• Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817--330
• The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku
• X-ray emission from black-hole binaries
• On the determination of the spin of the black hole in Cyg X-1 from X-ray reflection spectra
• Probing the Inner Region of Cyg X-1 in the Low/Hard State through its X-ray Broad Band Spectrum
• NuSTAR and Suzaku observations of the hard state in Cygnus X-1: locating the inner accretion disk
• The quiescent light curve and evolutionary state of GRO J1655-40
• Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State
• Suzaku Observations of Abell 1795: Cluster Emission to R_200
• Swift Observations of the Cooling Accretion Disk of XTE J1817-330
• The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk
• Suzaku Results on Cygnus X-1 in the Low/Hard State
• Broad band spectrum of Cygnus X-1 in two spectral states with BeppoSAX
• Cross-calibration of the X-ray Instruments onboard the Chandra, INTEGRAL, RXTE, Suzaku, Swift, and XMM-Newton Observatories using G21.5-0.9
• On the determination of the spin and disc truncation of accreting black holes using X-ray reflection
• The complex accretion geometry of GX 339-4 as seen by NuSTAR and Swift
• Superorbital variability of X-ray and radio emission of Cyg X-1 - II. Dependence of the orbital modulation and spectral hardness on the superorbital phase
• On the origin of spectral states in accreting black holes
• A re--analysis of the iron line in the XMM-Newton data from the low/hard state in GX339--4
• Broad-band spectra of Cyg X-1 and correlations between spectral characteristics
• The truncated and evolving inner accretion disc of the black hole GX 339-4
• Broadband X-ray Spectra of GX 339-4 and the Geometry of Accreting Black Holes in the Hard State
• Wind Accretion and State Transitions in Cygnus X-1
• The soft X-ray emission of Ark 120. XMM-Newton, NuSTAR, and the importance of taking the broad view
• X-ray and soft gamma-ray spectra of Broad-Line Radio Galaxies
• Patterns of energy-dependent variability from Comptonization
• Spectral analysis of the XMM-Newton data of GX 339-4 in the low/hard state: disc truncation and reflection
• The soft component and the iron line as signatures of the disc inner radius in Galactic black hole binaries
• Relativistic Distortions in the X-ray Spectrum of Cyg X-1
• The MeV spectral tail in Cyg X-1 and optically-thin emission of jets
• The Distribution of X-ray Dips with Orbital Phase in Cygnus X-1
• Using the X-ray Dust Scattering Halo of Cygnus X-1 to determine distance and dust distributions
• Evolution of the reverberation lag in GX 339-4 at the end of an outburst
• The detection and X-ray view of the changing look AGN HE 1136-2304
• On the Role of the Accretion Disk in Black Hole Disk-Jet Connections
• Evidence for a Cool Disk and Inhomogeneous Coronae from Wide-band Temporal Spectroscopy of Cygnus X-1 with Suzaku
• Long term variability of Cygnus X-1: VII. Orbital variability of the focussed wind in Cyg X-1 / HDE 226868 system
• On the lamppost model of accreting black holes
• Masses of the components of the HDE 226868/Cyg X-1 binary system
• The Impact of Accurate Extinction Measurements for X-ray Spectral Models
• The reverberation lag in the low mass X-ray binary H1743-322
• Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission
• X-ray time lags from a pivoting power law in black holes
• Black hole spin of Cyg X-1 determined from the softest state ever observed
• Fast Spectral Variability from Cygnus X-1
• A study of spectral and timing properties of Cyg X-1 based on a large sample of pointed RXTE observations
• Timescale Resolved Spectroscopy of Cyg X-1
• Minimum X-ray source size for a lamp-post corona in light-bending models for AGN

Cited by in corpus (50)

• Towards precision measurements of accreting black holes using X-ray reflection spectroscopy
• Alternative explanations for extreme supersolar iron abundances inferred from the energy spectrum of Cygnus X-1
• A public relativistic transfer function model for X-ray reverberation mapping of accreting black holes
• Accretion disks and coronae in the X-ray flashlight
• Reflection Spectra of the Black Hole Binary Candidate MAXI J1535-571 in the Hard State Observed by NuSTAR
• Doughnut strikes sandwich: the geometry of hot medium in accreting black hole X-ray binaries
• Detection of Coronal Magnetic Activity in Nearby Active Supermassive Black Holes
• Reverberation Reveals the Truncated Disc in the Hard State of GX 339-4
• Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry
• The obscured X-ray binaries V404 Cyg, Cyg X-3, V4641 Sgr, and GRS 1915+105
• Multi-timescale X-ray reverberation mapping of accreting black holes
• Improved spectral models for relativistic reflection
• A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070
• A Physical Model for the Spectral-Timing Properties of Accreting Black Holes
• A new lepto-hadronic model applied to the first simultaneous multiwavelength data set for Cygnus X--1
• An X-ray reverberation mass measurement of Cygnus X-1
• A variable corona during the transition from type-C to type-B quasi-periodic oscillations in the black hole X-ray binary MAXI J1820+070
• Modelling correlated variability in accreting black holes: the effect of high density and variable ionisation on reverberation lags
• Two major constraints on the inner radii of accretion disks
• A spectral study of the black hole X-ray binary MAXI J1820+070 with AstroSat and NuSTAR
• Detailed analysis on the reflection component for the black hole candidate MAXI J1348-630
• NuSTAR monitoring of MAXI J1348-630: evidence of high density disc reflection
• Breaking the spectral degeneracies in black hole binaries with fast timing data
• Coronal properties of black hole X-ray binaries in the hard state as seen by NuSTAR and Swift
• New insights on the puzzling LMXB 1RXS J180408.9-342058: the intermediate state, the clocked type-I X-ray bursts and much more
• A spectrally stratified hot accretion flow in the hard state of MAXI J1820+070
• Does the disk in the hard state of XTE J1752-223 extend to the innermost stable circular orbit?
• Accretion geometry of the black hole binary MAXI J1820+070 probed by frequency-resolved spectroscopy
• AstroSat and MAXI view of Cygnus X-1: Signature of an `extreme' soft nature
• The lamppost model: effects of photon trapping, the bottom lamp and disc truncation
• Common origin for black holes in both high mass X-ray binaries and gravitational-wave sources
• High hard X-ray polarization in Cygnus X-1 confined to the intermediate hard state: evidence for a variable jet component
• Comprehensive UV and Optical spectral analysis of Cygnus X-1: Stellar and wind parameters, abundances, and evolutionary implications
• Color-color diagrams as tools for assessment of the variable absorption in high mass X-ray binaries
• The X-ray spectral-timing contribution of the stellar wind in the hard state of Cyg X-1
• Probing the shot behaviour in Cygnus X-1 using simultaneous AstroSat-NICER observation
• A Model for Spectral States and Their Transition in Cyg X-1
• A NuSTAR and Swift View of the Hard State of MAXI J1813-095
• Evolution of Accretion Modes between Spectral States Inferred from Spectral and Timing Analysis of Cygnus X-1 with Insight-HXMT observations
• Clumpy wind accretion in Cygnus X-1
• Proof of principle X-ray reflection mass measurement of the black hole in H1743-322
• Broadband Spectral properties of MAXI J1348--630 using AstroSat Observations
• Broadband X-ray Spectroscopy and Estimation of Spin of the Galactic Black Hole Candidate GRS 1758-258
• Measuring black hole spins with x-ray reflection spectroscopy: A GRMHD outlook
• Polarized X-rays Correlated with Short--Timescale Variability of Cygnus X-1
• Lamp-post with an outflow and the hard state of Cyg X-1
• Systematic Analysis of Low/Hard State RXTE Spectra of GX 339-4 to Constrain the Geometry of the System
• Tracking the evolution of the accretion flow in MAXI J1820+070 during its hard state with the JED-SAD model
• Interaction between disk and extended corona in a general relativistic framework
• Assessing systematic uncertainties from spectral re-analysis of Cyg X-1 with different coronal geometries