Related papers: Supermassive Binary Black Hole Evolution can be tr…
We present analysis of Chandra X-ray observations of seven quasars that were identified as candidate sub-parsec binary supermassive black hole (SMBH) systems in the Catalina Real-Time Transient Survey (CRTS) based on apparent periodicity in…
The combined University of Michigan Radio Astronomy Observatory (UMRAO) and Owens Valley Radio Observatory (OVRO) blazar monitoring programs at 14.5/15 GHz provide uninterrupted light curves of $\sim~46-50$ yr duration for 83 blazars,…
We present an exploration of the expected detection of the earliest Active Galactic Nuclei (AGN) in the Universe from state-of-art galaxy formation and evolution semi-analytic models and hydro-dynamical simulations. We estimate the number…
The recently observed chirping signature in the light curves of Seyfert 1 galaxy SDSSJ1430$+$2303 could be explained by a late-inspiralling supermassive binary black hole (SMBBH) system in the galactic center, which will merge in the near…
The dynamical formation of binary black holes (BBHs) in globular clusters (GCs) may contribute significantly to the observed gravitational wave (GW) merger rate. Furthermore, LISA may detect many BBH sources from GCs at mHz frequencies,…
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has recently reported evidence for the presence of a common stochastic signal across their array of pulsars. The origin of this signal is still unclear. One of the…
In several previous studies, quasars exhibiting broad emission lines with >1000 km/s velocity offsets with respect to the host galaxy rest frame have been discovered. One leading hypothesis for the origin of these velocity-offset broad…
Direct-collapse black holes (DCBHs) forming at $z \sim$ 20 are currently the leading candidates for the seeds of the first quasars, over 200 of which have now been found at $z >$ 6. Recent studies suggest that DCBHs could be detected in the…
We have performed population synthesis calculation on the formation of binaries containing a black hole (BH) and a neutron star (NS) in the Galactic disk. Some of important input parameters, especially for the treatment of common envelope…
The discovery of gravitational-wave (GW) signals, produced by the coalescence of stellar-mass binary black holes (SBBHs), opens a new window to study the astrophysical origins and dynamical evolutions of compact binaries. In addition, these…
Pulsar timing array (PTA) provides an excellent opportunity to detect the gravitational waves (GWs) in nanoHertz frequency band. In particular, due to the larger number of "arms" in PTA, it can be used to test gravity by probing the…
A list of candidates for \textit{supermassive binary black holes} (SMBBHs), compiled from available data on the variability in the optical range and the shape of the emission spectrum, is analysed. An artificial neural network is…
We discuss the possibility of detecting the presence of primordial black holes (PBHs), such as those that might account for galactic dark matter, using modification of pulsar timing residuals when PBHs pass within ~1000 AU and impart…
The Square Kilometer Array (SKA) will enable studies of star formation in nearby galaxies with a level of detail never before possible outside of the Milky Way. Because the earliest stages of stellar evolution are often inaccessible at…
Eccentric binary black holes (BBHs) formed through dynamical interactions can significantly contribute to gravitational wave (GW) detections. In this work, we present a simulated catalog of dynamically-formed, stellar-mass BBHs in the local…
Galaxy centers are residing places for Super Massive Black Holes (SMBHs). Galaxy mergers bring SMBHs close together to form gravitationally bound binary systems which, if able to coalesce in less than a Hubble time, would be one of the most…
Several Pulsar Timing Array (PTA) collaborations have recently found evidence for a gravitational wave background (GWB) permeating our galaxy. The origin of this background is still unknown. Indeed, while the gravitational wave emission…
Probing the nature of dark matter (DM) remains an outstanding problem in modern cosmology. The 21 cm signal, as a sensitive tracer of neutral hydrogen during cosmic dawn, provides a unique means to investigate DM nature during this critical…
Distinguishing the photon output of an accreting supermassive black hole binary system from that of a single supermassive black hole accreting at the same rate is intrinsically difficult because the majority of the light emerges from near…
Elusive supermassive black hole binaries (SMBHBs) are thought to be the penultimate stage of galaxy mergers, preceding a final coalescence phase. SMBHBs are sources of continuous gravitational waves, possibly detectable by pulsar timing…