Evaluating Spectral Models and the X-ray States of Neutron-Star X-ray Transients

Abstract

We propose a hybrid model to fit the X-ray spectra of atoll-type X-ray transients in the soft and hard states. This model uniquely produces luminosity tracks that are proportional to T^4 for both the accretion disk and boundary layer. The model also indicates low Comptonization levels for the soft state, gaining a similarity to black holes in the relationship between Comptonization level and the strength of integrated rms variability in the power density spectrum. The boundary layer appears small, with a surface area that is roughly constant across soft and hard states. This result may suggestion that the NS radius is smaller than its inner-most stable circular orbit.

arXiv comment15 pages, 15 figures, accepted for publication in the ApJ

References in corpus (38)

• X-ray Properties of Black-Hole Binaries
• First Results from the All-Sky Monitor on the Rossi X-ray Timing Explorer
• Calibration of the Rossi X-ray Timing Explorer Proportional Counter Array
• Going with the flow: can the base of jets subsume the role of compact accretion disk coronae?
• In-flight Performance of the High Energy X-ray Timing Experiment on the Rossi X-ray Timing Explorer
• Jets in neutron star X-ray binaries: a comparison with black holes
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• Hard X-ray Emission From Low Mass X-ray Binaries
• Hysteresis in the Light Curves of Soft X-ray Transients
• Accretion Disk Boundary Layers Around Neutron Stars: X-ray Production in Low-Mass X-ray Binaries
• Boundary layer, accretion disk and X-ray variability in luminous LMXBs
• Observing the effects of the event horizon in black holes
• The Discovery of a State Dependent Hard Tail in the X-ray Spectrum of the Luminous Z-source GX 17+2
• The atoll source states of 4U 1608-52
• A Prominent Accretion Disk in the Low-Hard State of the Black Hole Candidate SWIFT J1753.5-0127
• How Do Z and Atoll X-ray Binaries Differ?
• Quiescent Thermal Emission from the Neutron Star in Aql X-1
• The broad band X-ray/hard X-ray spectra of accreting neutron stars
• Spectra of the spreading layers on the neutron star surface and constraints on the neutron star equation of state
• The X-ray spectrum of the atoll source 4U 1608-52
• The variable cyclotron line in GX 301-2
• A peculiar spectral state transition of 4U1705--44: when an Atoll looks like a Z
• Spectral Fits to the 1999 Aql X-1 Outburst Data
• Results of a LMXB survey: variation in the height of the neutron star blackbody emission region
• A comment on the colour-colour diagrams of Low Mass X-ray Binaries
• Simultaneous BeppoSAX and RXTE observations of the X-ray burst sources GX 3+1 and Ser X-1
• The Broad Band Spectrum of MXB 1728-34 Observed by BeppoSAX
• The X-ray Spectrum of Cyg X-2
• Evolution of Spectral States of Aql X-1 during the 2000 Outburst
• Correlated Timing and Spectral Variations of the Soft X-ray Transient Aquila X-1: Evidence for an Atoll classification
• Timing properties and spectral states in Aquila X-1
• The transient hard X-ray tail of GX 17+2: new BeppoSAX results
• The Rates of type I X-ray Bursts from Transients Observed with RXTE: Evidence for Black Hole Event Horizons
• Correlated timing and spectral behavior of 4U 1705-44
• Simultaneous BeppoSAX and Rossi X-ray Timing Explorer observations of 4U1812-12
• Quasi-periodic oscillations and noise in neutron star and black-hole X-ray binaries
• Wide band observations of the new X-ray burster SAX J1747.0-2853 during the March 1998 outburst
• A comparison of neutron star blackbody luminosities in LMXB with the theory of accretion flow spreading on the stellar surface

Cited by in corpus (151)

• Modelling the behaviour of accretion flows in X-ray binaries
• Relativistic Lines and Reflection from the Inner Accretion Disks Around Neutron Stars
• Spectral States of XTE J1701-462: Link between Z and Atoll Sources
• Relativistic iron emission lines in neutron star low-mass X-ray binaries as probes of neutron star radii
• Black hole-like hysteresis and accretion states in neutron star low mass X-ray binaries
• Revisiting a fundamental test of the disc instability model for X-ray binaries
• Broad relativistic iron emission line observed in SAX J1808.4-3658
• XTE J1701-462 and its Implications for the Nature of Subclasses in Low-Magnetic-Field Neutron Star Low-Mass X-Ray Binaries
• Patterns of variability in Be/X-ray pulsars during giant outbursts
• Low-level accretion in neutron-star X-ray binaries
• ULX spectra revisited: Accreting, highly magnetized neutron stars as the engines of ultraluminous X-ray sources
• Accretion disks and coronae in the X-ray flashlight
• A Hard Look at the Neutron Stars and Accretion Disks in 4U 1636-53, GX 17+2, and 4U 1705-44 with $\text{NuSTAR}$
• Discovery of the Third Transient X-ray Binary in the Galactic Globular Cluster Terzan 5
• Detection of Reflection Features in the Neutron Star Low-Mass X-ray Binary Serpens X-1 with NICER
• On Relativistic Disk Spectroscopy in Compact Objects with X-ray CCD Cameras
• Partial accretion in the propeller stage of low mass X-ray binary Aql X--1
• NuSTAR Observations of the Accreting Atolls GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371
• Discovery of an Ultrasoft X-ray Transient Source in the 2XMM Catalog: a Tidal Disruption Event Candidate
• X-Ray and Near-Infrared Observations of GX 339-4 in the Low/Hard State with Suzaku and IRSF
• A self-consistent approach to the hard and soft states of 4U 1705-44
• XMM-Newton observations of GX 13+1: correlation between photoionised absorption and broad line emission
• A Deep Chandra ACIS Survey of M83
• A connection between accretion state and $\text{Fe K absorption}$ in an accreting neutron star: black hole-like soft state winds?
• Spectroscopic evidence for a low-mass black hole in SWIFT J1753.5-0127
• On the Fe K absorption - accretion state connection in the Galactic center neutron star X-ray binary AX J1745.6-2901
• Low-Mass X-ray Binaries
• A dichotomy between the hard state spectral properties of black hole and neutron star X-ray~binaries
• Radius Constraints from Reflection Modeling of Cygnus X-2 with NuSTAR and NICER
• A search for iron emission lines in the Chandra X-ray spectra of neutron star low-mass X-ray binaries
• X-ray polarimetry and spectroscopy of the neutron star low-mass X-ray binary GX 9+9: an in-depth study with IXPE and NuSTAR
• On the spreading layer emission in luminous accreting neutron stars
• The balance of power: accretion and feedback in stellar mass black holes
• Suzaku and BeppoSAX X-ray Spectra of the Persistently Accreting Neutron-Star Binary 4U 1705-44
• Soft lags in neutron star kHz Quasi Periodic Oscillations: evidence for reverberation?
• Broad iron line in the fast spinning neutron-star system 4U 1636-53
• Spectral and Timing Properties of Atoll Source 4U 1705-44 : LAXPC/AstroSat Results
• Disk reflection and a possible disk wind during a soft X-ray state in the neutron star low-mass X-ray binary 1RXS J180408.9-342058
• The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst
• Accretion Geometry of the Low-Mass X-ray Binary Aquila X-1 in the Soft and Hard States
• The identification of MAXI J1659-152 as a black hole candidate
• Truncation of the Accretion Disk at One Third of the Eddington Limit in the Neutron Star Low-Mass X-ray Binary Aquila X-1
• On the nature of the first transient Z-source XTE J1701-462: its accretion disk structure, neutron star magnetic field strength, and hard tail
• NICER-NuSTAR Observations of the Neutron Star Low-Mass X-ray Binary 4U 1735-44
• Four new black hole candidates identified in M31 globular clusters with Chandra and XMM-Newton
• NuSTAR + XMM-Newton monitoring of the neutron star transient AX J1745.6-2901
• NuSTAR view of the Z-type neutron star low-mass X-ray binary Cygnus~X--2
• The Galactic LMXB Population and the Galactic Centre Region
• Relativistically broadened iron line in the SUZAKU observation of the neutron star X-ray binary 4U 1705-44
• Suzaku Studies of Luminosity-Dependent Changes in the Low-Mass X-ray Binary Aquila X-1
• Spectral states evolution of 4U 1728-34 observed by INTEGRAL and RXTE: non-thermal component detection
• A test of the nature of the Fe K Line in the neutron star low-mass X-ray binary Serpens X-1
• Comparing the Accretion Disk Evolution of Black Hole and Neutron Star X-ray Binaries from Low to Super-Eddington Luminosity
• The complex evolution of the X-ray binary transient MAXI J1807+132 along the decay of its discovery outburst
• Spectral state evolution of 4U~1820-30: the stability of the spectral index of Comptonization tail
• X-ray Spectral and Timing evolution of MAXI J1727-203 with NICER
• The chemical composition of the accretion disk and donor star in Ultra Compact X-ray Binaries: A comprehensive X-ray analysis
• On the Spin of the Black Hole in IC 10 X-1
• The spectral-timing properties of upper and lower kHz QPOs
• Suzaku View of the Neutron Star in the Dipping Source 4U 1822$-$37
• On the disc reflection spectroscopy of NS LMXB Serpens~X-1: analysis of a recent NuSTAR observation
• Investigating the nature of absorption lines in the Chandra X-ray spectra of the neutron star binary 4U 1820-30
• Spectral Evolution of a New X-ray Transient MAXI J0556-332 Observed by MAXI, Swift, and RXTE
• Simultaneous NICER and NuSTAR Observations of the Ultra-compact X-ray Binary 4U 1543-624
• Discovery of a Highly Variable Dipping Ultraluminous X-ray source in M94
• Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53
• Relativistic Disk Reflection in the Neutron Star X-ray Binary XTE J1709-267 with NuSTAR
• Simplified Picture of Low Mass X-ray Binaries based on Data from Aql X-1 and 4U1608-52
• Constraining the size of the Comptonizing medium by modeling the energy dependent time-lags of kHz QPOs of Neutron star system
• A variable near-infrared counterpart to the neutron-star low-mass X-ray binary 4U 1705-440
• Classification of X-ray Sources in the XMM-Newton Serendipitous Source Catalog: Objects of Special Interest
• Cosmological implications of the composite spectra of galactic X-ray binaries constructed using MAXI data
• StrayCats: A catalog of NuSTAR Stray Light Observations
• Spectral Softening Between Outburst and Quiescence In The Neutron Star Low-Mass X-Ray Binary SAX J1750.8-2900
• NuSTAR and Chandra observations of new X-ray transients in the central parsec of the Galaxy
• High-frequency variability in neutron-star low-mass X-ray binaries
• INTEGRAL and BeppoSAX observations of the transient atoll source 4U 1608-522: from quiescent to hard spectral state
• Relation between spectral changes and the presence of the lower kHz QPO in the neutron-star low-mass X-ray binary 4U 1636-53
• Slow and Fast Transitions in the Rising Phase of Outbursts from NS-LMXB transients, AqlX-1 and 4U1608-52
• Chandra identification of 26 new black hole candidates in the central region of M31
• Around 200 new X-ray binary IDs from 13 years of Chandra observations of the M31 center
• Spectral properties of MXB 1658-298 in the low/hard and high/soft state
• Evolution of cross-correlation and time lag of 4U 1735-44 along the branches
• 50 M31 black hole candidates identified by Chandra and XMM-Newton
• Are the kHz QPO lags in neutron star 4U 1608-52 due to reverberation?
• Constraining the Coronal Heights and Readjustment Velocities Based on the Detection of a Few Hundred Seconds Delays in the Z Source GX 17+2
• Observations of the Ultra-compact X-ray Binary 4U 1543-624 in Outburst with NICER, INTEGRAL, Swift, and ATCA
• A NICER look at the Aql X-1 hard state
• The broadband spectral analysis of 4U 1702-429 using XMM-Newton and BeppoSAX data
• A model-independent comparison of the variability of accreting neutron stars and black holes
• Evidence of spreading layer emission in thermonuclear superbursts
• On the origin of the hard X-ray tail in neutron-star X-ray binaries
• Discovery of transition from marginally stable burning to unstable burning after a superburst in Aql X-1
• Spectral evolution of the X-ray nova XTE J1859+226 during its outburst observed by BeppoSAX and RXTE
• Study of the reflection spectrum of the bright atoll source GX 3+1 with NuSTAR
• Discovery of the new X-ray transient MAXI J1807+132: a Candidate of a Neutron Star Low-mass X-ray binary
• Broadband X-ray emission and the reality of the broad iron line from the Neutron Star - White Dwarf X-ray binary 4U 1820-30
• RXTE Observations of the Low-Mass X-Ray Binary 4U 1608-522 in Upper-Banana State
• X-ray softening during the 2008 outburst of XTE J1810-189
• A Hard-to-Soft State Transition of Aquila X-1 Observed with Suzaku
• Catalog of outbursts of neutron star LMXBs
• Multi-wavelength spectroscopy of the black hole candidate MAXI J1813-095 during its discovery outburst
• The amplitude of the kilohertz quasi-periodic oscillations in 4U 1636$-$53 in the frequency-energy space
• Unveiling the nature of compact object in the LMXB MAXI J1957+032 using Swift-XRT
• Detection of millihertz quasi-periodic oscillations in the low-mass X-ray binary 4U 1730--22 with NICER
• Outbursts from IGR J17473-2721
• The properties of cross-correlation and spectra of the low-mass X-ray binary 4U 1608-52
• Broad-band spectral analysis of LMXB XTE J1710-281 with Suzaku
• The very faint hard state of the persistent neutron star X-ray binary SLX 1737-282 near the Galactic centre
• AstroSat view of the neutron star low-mass X-ray binary GX 340+0
• X-ray Spectral Analysis of the Steady States of GRS 1915+105
• The Megasecond Chandra X-Ray Visionary Project Observation of NGC 3115 (II): properties of point sources
• Optical nebular emission following the most luminous outburst of Aquila X-1
• State Transitions in Ultracompact Neutron Star LMXBs: towards the Low Luminosity Limit
• A Suzaku Observation of the Low-Mass X-Ray Binary GS 1826-238 in the Hard State
• Monte Carlo Simulations of Thermal Comptonization Process in a Two Component Advective Flow around a Neutron Star
• Disappearance of the Fe K$\alpha$ emission line in Ultra Compact X-ray Binaries 4U 1543-624 and Swift J1756.9-2508
• Evidence of disc reflection in the X-ray spectrum of the neutron star low mass X-ray binary 4U 1636-536
• Swift monitoring of Cygnus X-2: investigating the NUV-X-ray connection
• Spectral Properties of X-ray Binaries in Centaurus A
• Suzaku Observation of the Symbiotic X-Ray Binary IGR J16194-2810
• Spectral-Timing Analysis of the Lower kHz QPO in the Low-Mass X-ray Binary Aquila X-1
• Transient X-ray source population in the Magellanic-type galaxy NGC 55
• A Monte Carlo estimate for the fraction of thermal Comptonized photons that impinge back on the soft source in neutron star LMXBs
• The hard X-ray emission along the "Z" track in GX 17+2
• Probing spectral and temporal evolution of the neutron star low-mass X-ray binary 4U 1724-30 with AstroSat
• Anti-Correlated lags in a Neutron star Z source GX 5-1: AstroSat's View
• Understanding the Inner Structure of Accretion disk in GX 17+2: AstroSat's Outlook
• Probing the accretion geometry of the atoll source 4U 1702-429 in different spectral states with NICER, NuSTAR, and AstroSat
• Evolution of the Accretion Disk and Corona During the Outburst of the Neutron Star Transient MAXI J1807+132
• Discovery of a new black hole transient within 100" (400 pc) of M31*
• Broadband observations of the X-ray burster 4U 1705-44 with BeppoSAX
• Accretion disc winds in X-ray binaries
• Evaluating the jet/accretion coupling of Aql X-1: probing the contribution of accretion flow spectral components
• Investigating the coronal structure by studying time lags in the Atoll source 4U 1705-44 using AstroSat
• The advection-dominated accretion flow for the anti-correlation between the X-ray photon index and the X-ray luminosity in neutron star low-mass X-ray binaries
• Timing and spectral study of XB 1254-690 using new RXTE PCA data
• Modeling the upper kHz QPOs of 4U 1728-34 with X-ray reverberation
• An enigmatic hump around 30 keV in Suzaku spectra of Aquila X-1 in the Hard State
• A solution to the tension of burning on neutron stars and nuclear physics
• AstroSat View of Transient Low-mass X-ray Binary XTE J1701-462: Spectral and Temporal Evolution along the Z-track
• A Detailed Spectral Study of Intermittent-Accreting Millisecond X-ray Pulsar Aql X-1 during Pulse-on and Pulse-off Stages
• Results from Long-Term Optical Monitoring of the Soft X-Ray Transient SAX J1810.8-2609
• XMM-Newton and Chandra observations of the M31 globular cluster black hole candidate XB135: a heavyweight contender cut down to size
• The X-ray bursts within the 2010 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021
• The first extragalactic ultra-compact X-ray binary : a candidate black hole-white dwarf system
• The NuSTAR view of Ultra-Compact X-ray Binaries
• A NICER and AstroSat view of the neutron star low-mass X-ray binary 1A 1246-588
• A "Hyperburst" in the MAXI J0556-332 Neutron Star: Evidence for a New Type of Thermonuclear Explosion
• Tracing the outburst decay of soft X-ray transients Aql X-1 and 4U 1608-52 with XSPECT
• Resolving SLX 1744-299 and SLX 1744-300 in the hard X-ray band: implications for their ultracompact nature