A hard X-ray study of the ultraluminous X-ray source NGC 5204 X-1 with NuSTAR and XMM-Newton

Journal Article · Mon Jul 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/808/1/64· OSTI ID:22882873

Mukherjee, E. S.; Walton, D. J.; Harrison, F. A.; Bellm, E.; Fuerst, F.; Grefenstette, B. W.; Madsen, K. K.; Rana, V. ^[1]; Bachetti, M.; Barret, D. ^[2]; Boggs, S. E.; Craig, W. W. ^[3]; Christensen, F. E. ^[4]; Fabian, A. C.; Middleton, M. J. ^[5]; Hailey, C. J. ^[6]; Miller, J. M. ^[7]; Stern, D. ^[8]; Zhang, W. ^[9]

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1. Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)
2. Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France)
3. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
4. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
5. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
6. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
7. Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 49109-1107 (United States)
8. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
9. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

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{sub X}=(4.95±0.11)×10{sup 39} erg s{sup −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 and Sunyaev thin disk.

• OSTI ID: 22882873
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 808; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
COSMIC X-RAY SOURCES
DETECTION
HARD X RADIATION
KEV RANGE
LUMINOSITY
MASS
SPECTRA
TELESCOPES