Journal article
Detection of Strong Short-Term Variability in NGC 6946 X-1
The Astrophysical journal, Vol.722(1), pp.620-624
08/12/2010
DOI: 10.1088/0004-637X/722/1/620
Abstract
Using two archival XMM-Newton observations, we identify strong X-ray flux
variations in NGC 6946 X-1 indicating it is the most variable ultraluminous
X-ray source (ULX) on mHz time scales known so far. The 1-10 keV lightcurve
exhibits variability with a fractional rms amplitude of 60% integrated in the
frequency range of 1-100 mHz. The power spectral density of the source shows a
flat-topped spectrum that breaks at about 3 mHz with possible quasi-periodic
oscillations (QPOs) near 8.5 mHz. Black hole binaries usually produce strong
fast variability in the hard or intermediate state. The energy spectrum of NGC
6946 X-1 is dominated by two components, a 0.18~keV thermal disk and a power
law with a photon index of ~2.2, which is consistent with the intermediate
state. The characteristic time scales of the X-ray emission suggests that the
ULX may contain a black hole with a mass on the order of 10^3.
Details
- Title: Subtitle
- Detection of Strong Short-Term Variability in NGC 6946 X-1
- Creators
- Fengyun Rao - Tsinghua UniversityHua Feng - Tsinghua UniversityPhilip Kaaret - University of Iowa
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.722(1), pp.620-624
- DOI
- 10.1088/0004-637X/722/1/620
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Publisher
- Institute of Physics (IOP)
- Language
- English
- Date published
- 08/12/2010
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199762002771
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