Systematic Analysis of Low/Hard State RXTE Spectra of GX 339-4 to Constrain the Geometry of the System

Abstract

One of the popular models for the low/hard state of Black Hole Binaries is that the standard accretion disk is truncated and the hot inner region produces via Comptonization, the hard X-ray flux. This is supported by the value of the high energy photon index, which is often found to be small $\sim$ 1.7 ($<$ 2) implying that the hot medium is seed photons starved. On the other hand, the suggestive presence of a broad relativistic Fe line during the hard state would suggest that the accretion disk is not truncated but extends all the way to the inner most stable circle orbit. In such a case, it is a puzzle why the hot medium would remain photon starved. The broad Fe line should be accompanied by a broad smeared reflection hump at $\sim$ 30 keV and it may be that this additional component makes the spectrum hard and the intrinsic photon index is larger, i.e. $>$ 2. This would mean that the medium is not photon deficient, reconciling the presence of a broad Fe line in the observed hard state. To test this hypothesis, we have analyzed the RXTE observations of GX 339-4 from the four outbursts during 2002-2011 and identify the observations when the system was in the hard state and showed a broad Fe line. We have then attempted to fit these observations with models, which include smeared reflection to understand whether the intrinsic photon index can indeed be large. We find that, while for some observations the inclusion of reflection does increase the photon index, there are hard state observations with broad Fe line that have photon indices less than 2.

arXiv comment12pages, 5figues, submitted to RAA

References in corpus (35)

• 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
• The evolution of black hole states
• Jets from black hole X-ray binaries: testing, refining and extending empirical models for the coupling to X-rays
• States and transitions in black-hole binaries
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• Dynamical Evidence for a Black Hole in GX 339-4
• Evidence for Spin and Energy Extraction in a Galactic Black Hole Candidate: The XMM-Newton/EPIC-pn Spectrum of XTE J1650-500
• Black hole accretion disks in the canonical low-hard state
• A systematic look at the Very High and Low/Hard state of GX 339-4: Constraining the black hole spin with a new reflection model
• The Distance and Interstellar Sight Line to GX339-4
• X-ray irradiation in XTE J1817-330 and the inner radius of the truncated disc in the hard state
• A Prominent Accretion Disk in the Low-Hard State of the Black Hole Candidate SWIFT J1753.5-0127
• The Relativistic Fe Emission Line in XTE J1650-500 with BeppoSAX: Evidence for Black Hole Spin and Light Bending Effects?
• Truncation of the Inner Accretion Disk around a Black Hole at Low Luminosity
• Swift Observations of the Cooling Accretion Disk of XTE J1817-330
• Two-temperature coronal flow above a thin disk
• A Swift survey of accretion onto stellar-mass black holes
• Long term variability of Cygnus X-1 V. State definitions with all sky monitors
• A re--analysis of the iron line in the XMM-Newton data from the low/hard state in GX339--4
• The truncated and evolving inner accretion disc of the black hole GX 339-4
• Truncated disc versus extremely broad iron line in XTE J1650-500
• Revealing accretion onto black holes: X-ray reflection throughout three outbursts of GX 339-4
• Analysis of NuSTAR and Suzaku observations of Cyg X-1 in the hard state: evidence for a truncated disc geometry
• 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
• On the variation of black hole accretion disc radii as a function of state and accretion rate
• X-Ray and Near-Infrared Observations of GX 339-4 in the Low/Hard State with Suzaku and IRSF
• Evidence for a Cool Disk and Inhomogeneous Coronae from Wide-band Temporal Spectroscopy of Cygnus X-1 with Suzaku
• The Dependence of Spectral State Transition and Disk Truncation on Viscosity Parameter $α
• The return to the hard state of GX 339-4 as seen by Suzaku
• The formation of the coronal flow/ADAF
• Suzaku broadband spectroscopy of Swift J1753.5-0127 in the Low-Hard State
• Thermal emission from the stellar-mass black hole binary XTE J1118+480 in the low/hard state

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