Please use this identifier to cite or link to this item:
Title: Patchy Accretion Disks in Ultra-luminous X-Ray Sources
Authors: Miller, J. M
Bachetti, M.
Rana, V
+5 Co-Authors
Keywords: accretion
accretion disks
black hole physics
X-rays: binaries
Issue Date: 10-Apr-2014
Publisher: IOP Sciences for American Astronomical Society
Citation: The Astrophysical Journal Letters, 2014, Vol.785, p6
Abstract: The X-ray spectra of the most extreme ultra-luminous X-ray sources—those with L >= 1040 erg s-1—remain something of a mystery. Spectral roll-over in the 5-10 keV band was originally detected 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 (kTe ~= 2 keV) and high optical depths (τ ~= 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 and other low-mass active galactic nuclei.
Description: Open Access
ISSN: 0004-637X
1538-4357 (online)
Alternative Location:
Copyright: 2014 The American Astronomical Society.
Appears in Collections:Research Papers (A&A)

Files in This Item:
File Description SizeFormat 
2014_ApJL_Vol.785_pL7.pdfOpen Access1.11 MBAdobe PDFView/Open

Items in RRI Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated.