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Constraining the origin of the nanohertz gravitational-wave background by pulsar timing array observations of both the background and individual supermassive binary black holes
Yunfeng Chen, Qingjuan Yu, Youjun Lu
The gravitational waves (GWs) from supermassive binary black holes (BBHs) are long sought by pulsar timing array experiments (PTAs), in the forms of both a stochastic GW background…
Pulsar timing array detections of supermassive binary black holes: implications from the detected common process signal and beyond
Yunfeng Chen, Qingjuan Yu, Youjun Lu
Pulsar timing arrays (PTAs) are anticipated to detect the stochastic gravitational wave background (GWB) from supermassive binary black holes (BBHs) as well as the gravitational wa…
The correlations of stellar tidal disruption rates with properties of massive black holes and their host galaxies
Yunfeng Chen, Qingjuan Yu, Youjun Lu
Stars can be either disrupted as tidal disruption events (TDEs) or swallowed as a whole by massive black holes (MBHs) at galactic centers when they approach sufficiently close to t…
On Detecting Nearby Nano-Hertz Gravitational Wave Sources via Pulsar Timing Arrays
Xiao Guo, Youjun Lu, Qingjuan Yu
Massive binary black holes (MBBHs) in nearby galactic centers, if any, may be nano-Hertz gravitational wave (GW) sources for pulsar timing arrays (PTAs) to detect. Normally the obj…
Investigating the existence of gravitomagnetic monopole in M87*
M. Ghasemi-Nodehi, Chandrachur Chakraborty, Qingjuan Yu +1
We examine the possibility for the existence of gravitomagnetic monopole () in M87* by using the results obtained from its first Event Horizon Telescope image. By numerically…
Black holes and the supermassive compact object at the Galactic center: multi-arts of thought and nature
Qingjuan Yu
This is an invited commentary on the Nobel Prize in Physics 2020 which was awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the gener…
Cosmic distributions of stellar tidal disruptions by massive black holes at galactic centers
Yunfeng Chen, Qingjuan Yu, Youjun Lu
Stars can be consumed (either tidally disrupted or swallowed whole) by massive black holes (MBHs) at galactic centers when they move into the vicinity of the MBHs. In this study, w…
Dynamical evolution of cosmic supermassive binary black holes and their gravitational wave radiation
Yunfeng Chen, Qingjuan Yu, Youjun Lu
We investigate the evolution of supermassive binary black holes (BBHs) in galaxies with realistic property distributions and the gravitational-wave (GW) radiation from the cosmic p…
X-ray Eclipses of Active Galactic Nuclei
Fupeng Zhang, Qingjuan Yu, Youjun Lu
X-ray variation is a ubiquitous feature of active galactic nuclei (AGNs), however, its origin is not well understood. In this paper, we show that the X-ray flux variations in some…
Prospects for constraining the spin of the massive black hole at the Galactic center via the relativistic motion of a surrounding star
Qingjuan Yu, Fupeng Zhang, Youjun Lu
In this paper, we investigate the quality of constraining the spin of the massive black hole (MBH) at the Galactic center (GC) by using full general relativistic simulations of the…
A probable Milli-Parsec Supermassive Binary Black Hole in the Nearest Quasar Mrk 231
Chang-Shuo Yan, Youjun Lu, Xinyu Dai +1
Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. Great effort has been made during the past…
On Testing the Kerr Metric of the Massive Black Hole in the Galactic Center via Stellar Orbital Motion: Full General Relativistic Treatment
Fupeng Zhang, Youjun Lu, Qingjuan Yu
The S-stars in the Galactic center (GC) are anticipated to provide unique dynamical constraint on the spin of the GC massive black hole (MBH). In this paper, we develop a fast full…