Speaker
鲍通
(Nanjing University)
Description
Recent X-ray observations have revealed
growing evidence of quasi-periodic oscillation (QPO) in the light curve of active galactic nuclei (AGNs), which may serve as a useful probe of black hole physics.
In this work, we present a systematic search for X-ray QPOs among $\sim$ 1000 AGNs of the Chandra Deep Field South (CDF-S) in a homogeneous fashion.
Dividing the 7-Ms Chandra observations into four epochs, we search for periodic signals that are persistent throughout any of these epochs, using two independent methods: Lomb-Scargle periodogram and Gregory-Loredo Algorithm.
No statistically significant periodic signal is found with either method on any of the four epochs.
Our extensive simulations of source light curves suggest that this non-detection is primarily due to a moderate sensitivity of the CDF-S data in QPO detection.
Using the simulation-predicted detection efficiency, we are able to provide a meaningful constraint on the intrinsic occurrence rate of persistent QPOs, $ < (15-20)\%$, provided that they share a similar power spectral density with a handful of currently known AGN QPOs.
The true intrinsic occurrence rate might be significantly below this upper limit, however, given the non-detection among the CDF-S sources.
Our additional search for short-lived QPOs that are only detected over a small subset of all observations results in two candidates, one in source XID 643 at a period of $\sim$ 13273 s and the other in source XID 876 at a period of $\sim$ 7065 s.
| Topic | 活动星系核与超大质量黑洞 |
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Primary author
鲍通
(Nanjing University)
