A Hard X-Ray Study of the Ultraluminous X-Ray Source NGC 5204 X-1 with NuSTAR and XMM-Newton

Journal
Date Issued
2015
Author(s)
Mukherjee, E. S.
•
Walton, D. J.
•
•
Harrison, F. A.
•
Barret, D.
•
Bellm, E.
•
Boggs, S. E.
•
Christensen, F. E.
•
Craig, W. W.
•
Fabian, A. C.
•
Fuerst, F.
•
Grefenstette, B. W.
•
Hailey, C. J.
•
Madsen, K. K.
•
Middleton, M. J.
•
Miller, J. M.
•
Rana, V.
•
Stern, D.
•
Zhang, W.
DOI
Description
The authors thank the referee for useful feedback which helped improve the final manuscript. This research has made use of data obtained with the NuSTAR mission, a project led by the California Institute of Technology (Caltech), managed by the Jet Propulsion Laboratory (JPL) and funded by NASA, and with XMM-Newton , an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software ( NUSTARDAS), jointly developed by the ASI Science Data Center (ASDC, Italy) and Caltech (USA).
Abstract
We present the results from coordinated X-ray observations of the ultraluminous X-ray source NGC 5204 X-1 performed by the Nuclear Spectroscopic Telescope Array and XMM-Newton in early 2013. These observations provide the first detection of NGC 5204 X-1 above 10 {keV}, extending the broadband coverage to 0.3-20 {keV}. The observations were carried out in two epochs separated by approximately 10 days, and showed little spectral variation with an observed luminosity of {L}{{X}}=(4.95+/- 0.11)× {10}39 erg s-1. The broadband spectrum robustly confirms the presence of a clear spectral downturn above 10 {keV} seen in some previous observations. This cutoff is inconsistent with the standard low/hard state seen in Galactic black hole binaries, as would be expected from an intermediate-mass black hole accreting at significantly sub-Eddington rates given the observed luminosity. The continuum is apparently dominated by two optically thick thermal-like components, potentially accompanied by a faint high-energy tail. The broadband spectrum is likely associated with an accretion disk that differs from a standard Shakura & Sunyaev thin disk.
Volume
808
Issue
1
Start page
64
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...808...64M
Rights
open.access
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