- Authors:
-
- Bachetti, Matteo ;
- Rana, Vikram ;
- Walton, Dominic J. ;
- Barret, Didier ;
- Harrison, Fiona A. ;
- Boggs, Steven E. ;
- Christensen, Finn Erland ;
- Craig, William W. ;
- Fabian, Andrew C. ;
- Fuerst, Felix ;
- Grefenstette, Brian W. ;
- Hailey, Charles J. ;
- Hornschemeier, Ann ;
- Madsen, Kristin K. ;
- Miller, Jon M. ;
- Ptak, Andrew F. ;
- Stern, Daniel ;
- Webb, Natalie A. ;
- Zhang, William W.
- DOI:
- 10.1088/0004-637X/778/2/163
- Abstract:
- We present the results of NuSTAR and XMM-Newton observations of the two ultraluminous X-ray sources: NGC 1313 X-1 and X-2. The combined spectral bandpass of the two satellites enables us to produce the first spectrum of X-1 between 0.3 and 30 keV, while X-2 is not significantly detected by NuSTAR above 10 keV. The NuSTAR data demonstrate that X-1 has a clear cutoff above 10 keV, whose presence was only marginally detectable with previous X-ray observations. This cutoff rules out the interpretation of X-1 as a black hole in a standard low/hard state, and it is deeper than predicted for the downturn of a broadened iron line in a reflection-dominated regime. The cutoff differs from the prediction of a single-temperature Comptonization model. Further, a cold disk-like blackbody component at similar to 0.3 keV is required by the data, confirming previous measurements by XMM-Newton only. We observe a spectral transition in X- 2, from a state with high luminosity and strong variability to a lower-luminosity state with no detectable variability, and we link this behavior to a transition from a super-Eddington to a sub-Eddington regime.
- Type:
- Journal article
- Language:
- English
- Published in:
- Astrophysical Journal, 2013, Vol 778, Issue 2
- Keywords:
- ASTRONOMY; MASS BLACK-HOLES; QUASI-PERIODIC OSCILLATIONS; SUPER-EDDINGTON ACCRETION; ACTIVE GALAXIES; BINARY-SYSTEMS; ESO 243-49; SLIM DISK; VARIABILITY; STATE; SPECTRA
- Main Research Area:
- Science/technology
- Publication Status:
- Published
- Review type:
- Peer Review
- Submission year:
- 2014
- Scientific Level:
- Scientific
- ID:
- 256282894
0000-0001-5679-1946
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