Patchy Accretion Disks in Ultraluminous X-ray Sources

Abstract

The X-ray spectra of the most extreme ultra-luminous X-ray sources -- those with L > 1 E+40 erg/s -- remain something of a mystery. Spectral roll-over in the 5-10 keV band was originally detected in in the deepest XMM-Newton observations of the brightest sources; this is confirmed in subsequent NuSTAR spectra. This emission can be modeled via Comptonization, but with low electron temperatures (kT_e ~ 2 keV) and high optical depths (tau ~ 10) that pose numerous difficulties. Moreover, evidence of cooler thermal emission that can be fit with thin disk models persists, even in fits to joint XMM-Newton and NuSTAR observations. Using NGC 1313 X-1 as a test case, we show that a patchy disk with a multiple temperature profile may provide an excellent description of such spectra. In principle, a number of patches within a cool disk might emit over a range of temperatures, but the data only require a two-temperature profile plus standard Comptonization, or three distinct blackbody components. A mechanism such as the photon bubble instability may naturally give rise to a patchy disk profile, and could give rise to super-Eddington luminosities. It is possible, then, that a patchy disk (rather than a disk with a standard single-temperature profile) might be a hallmark of accretion disks close to or above the Eddington limit. We discuss further tests of this picture, and potential implications for sources such as narrow-line Seyfert-1 galaxies (NLSy1s) and other low-mass active galactic nuclei (AGN).

Accepted for publication in ApJ Letters

References in corpus (38)

• On the Absorption of X-rays in the Interstellar Medium
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Ultraluminous X-Ray Sources in External Galaxies
• The Ultraluminous State
• Super-Eddington Fluxes from Thin Accretion Disks?
• A New Sample of Low-mass Black Holes in Active Galaxies
• 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
• A Simple Comptonization Model
• On the interpretation of the multicolour disc model for black hole candidates
• Discovery of X-ray QPOs from an Ultra-luminous X-ray Source in M82: Evidence Against Beaming
• A Comparison of Intermediate Mass Black Hole Candidate ULXs and Stellar-Mass Black Holes
• X-ray Spectral Properties of Low-Mass X-ray Binaries in Nearby Galaxies
• The ultraluminous X-ray sources NGC 1313 X-1 and X-2: a broadband study with NuSTAR and XMM-Newton
• Accretion disc coronae as magnetic reservoirs
• Photon Bubbles in Accretion Discs
• The most extreme ultraluminous X-ray sources: evidence for intermediate-mass black holes?
• Spectral variability of ultraluminous X-ray sources
• Quasi-Periodic Variability in NGC 5408 X-1
• Broad absorption features in wind-dominated ULXs?
• The variability of accretion onto Schwarzschild black holes from turbulent magnetized discs
• An Extremely Luminous and Variable Ultraluminous X-ray Source in the Outskirts of Circinus Observed with NuSTAR
• Super Eddington Slim Accretion Disks with Winds
• Revealing the X-ray source in IRAS 13224-3809 through flux-dependent reverberation lags
• Super-Eddington Atmospheres that Don't Blow Away
• Multiwavelength Observations of the SS 433 Jets
• X-ray spectral evolution in M33 X-8
• Unveiling recurrent jets of the ULX Holmberg II X-1: evidence for a massive stellar-mass black hole?
• X-ray spectral states and metallicity in the ultraluminous X-ray sources NGC 1313 X-1 and X-2
• X-ray Outflows and Super-Eddington Accretion in the Ultraluminous X-ray Source Holmberg IX X-1
• Broad-band X-Ray Spectra of the Black Hole Candidate GRO J1655-40
• Revisiting Putative Cool Accretion Disks in Ultraluminous X-ray Sources
• A long-term X-ray monitoring of the ultraluminous X-ray source NGC 5408 X-1 with Swift reveals the presence of dips but no orbital period
• A Multi-epoch Timing and Spectral Study of the Ultraluminous X-Ray Source NGC 5408 X-1 with XMM-Newton
• Searching for Massive Outflows in Holmberg IX X-1 and NGC 1313 X-1: The Iron K Band
• Inhomogeneous accretion discs and the soft states of black hole X-ray binaries
• Evolution of the spectral curvature in the ULX Holmberg II X-1
• Evidence for Quasi-periodic X-Ray Dips from an Ultraluminous X-Ray Source: Implications for the Binary Motion

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