Spectral State Transitions of the Ultraluminous X-ray Sources X-1 and X-2 in NGC 1313

Abstract

X-ray spectral state transitions are a key signature of black hole X-ray binaries and follow a well-defined pattern. We examined 12 XMM-Newton observations of the nearby spiral galaxy NGC 1313, which harbors two compact ultraluminous X-ray sources (ULXs), X-1 and X-2, in order to determine if the state transitions in ULXs follow the same pattern. For both sources, the spectra were adequately fitted by an absorbed power-law with the addition of a low temperature (kT=0.1~0.3 keV) disk blackbody component required in 6 of the 12 observations. As the X-ray luminosity of X-1 increases to a maximum at 3x10^40 ergs/s, the power-law photon index softens to 2.5-3.0. This behavior is similar to the canonical spectral state transitions in Galactic black hole binaries, but the source never enters the high/soft or thermal dominant state and instead enters the steep power-law state at high luminosities. X-2 has the opposite behavior and appears to be in the hard state, with a photon index of Gamma=1.7-2.0 at high luminosity, but can soften to Gamma=2.5 at the lower luminosities.

arXiv comment5 pages, 2 figures, submitted to ApJL on May 26th

References in corpus (34)

• Towards a unified model for black hole X-ray binary jets
• Ultraluminous X-Ray Sources in External Galaxies
• The Nature of Accreting Black Holes in Nearby Galaxy Nuclei
• The evolution of black hole states
• Radio / X-ray correlation in the low/hard state of GX 339--4
• Super-Eddington Fluxes from Thin Accretion Disks?
• X-ray Spectroscopic Evidence for Intermediate Mass Black Holes: Cool Accretion Disks in Two Ultra--Luminous X-ray Sources
• XMM-Newton observations of the brightest Ultraluminous X-ray sources
• Chandra High-Resolution Camera Observations of the Luminous X-Ray Source in the Starburst Galaxy M82
• Discovery of X-ray QPOs from an Ultra-luminous X-ray Source in M82: Evidence Against Beaming
• Population X: Are the super-Eddington X-ray sources beamed jets in microblazars or intermediate mass black holes?
• Deviations from the Local Hubble Flow. I. The Tip of the Red Giant Branch as a Distance Indicator
• The Three Spectral Regimes Found in the Stellar Black Hole XTE J1550--564 in its High/Soft State
• High Resolution Imaging of the HeII lambda 4686 Emission Line Nebula Associated with the Ultraluminous X-Ray Source in Holmberg II
• Radio Emission from an Ultraluminous X-Ray Source
• Long Term Variability of Cygnus X-1. IV. Spectral Evolution 1999-2004
• Discovery of Spectral Transitions from Two Ultra-Luminous Compact X-Ray Sources in Ic342
• Black Hole Mass of the Ultraluminous X-ray source M82 X-1
• The optical counterpart of an Ultra-luminous X-Ray Source in NGC 5204
• A 62 Day X-Ray Periodicity and an X-Ray Flare from the Ultraluminous X-Ray Source in M82
• A Transition to the Soft State in GRS 1758-258
• Displacement of X-Ray Sources from Star Clusters in Starburst Galaxies
• Accretion Disk Spectra of the Ultra-luminous X-ray Sources in Nearby Spiral Galaxies and Galactic Superluminal Jet Sources
• XMM-Newton Observations of Ultraluminous X-Ray Sources in Nearby Galaxies
• Beyond the standard accretion disc model: coupled magnetic disc--corona solutions with a physically motivated viscosity law
• The Ultra-luminous M81 X-9 source: 20 years variability and spectral states
• An Optical Study of Stellar and Interstellar Environments of Seven Luminous and Ultraluminous X-Ray Sources
• The Time-Variable Ultra-Luminous X-ray Sources of "The Antennae"
• A transition to a low/soft state in the ultra-luminous compact X-ray source Holmberg II X-1
• XMM-Newton EPIC observations of the ultraluminous X-ray source NGC 5204 X-1
• X-Ray Observations of the Black Hole Transient 4U 1630-47 During Two Years of X-Ray Activity
• A deep XMM-Newton observation of the ultraluminous X-ray source HoII X-1 : the case against a 1000 solar mass black hole
• The Orbital Period of the Ultraluminous X-ray Source in M82
• XMM-Newton Spectra of Intermediate-Mass Black Hole Candidates: Application of a Monte-Carlo Simulated Model

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