A Stable 3:2 Twin Peak X-ray Quasi-periodic Oscillation from an Ultraluminous X-ray Source: Evidence for a 400 solar mass black hole
Abstract
X-ray high-frequency quasi-periodic oscillations (HFQPOs: 100-450 Hz) in a 3:2 frequency ratio--hypothesized to originate from close to the event horizon--have only been observed from stellar-mass black holes. Such general relativity-induced oscillations are expected to scale inversely with the black hole mass. Thus, the detection of a twin peak oscillation in an ultraluminous X-ray source in the range of a few Hz has been proposed as strong evidence for the existence of intermediate-mass black holes. We report the discovery of stable, twin-peak (3:2 frequency ratio) X-ray quasi-periodic oscillations (QPOs) from an ultraluminous X-ray source. The two QPOs at 3.32+-0.06 Hz and 5.07+-0.06 Hz have rms amplitudes of 3-5%. Scaling the frequencies to HFQPOs of stellar-mass black holes of known mass implies that the black hole is 428+-105 solar masses. Our result not only strongly argues that some ULXs are indeed intermediate-mass black holes but also suggests that the physical phenomenon causing HFQPOs in stellar-mass black holes scales to intermediate-mass black holes.
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1412225P