Related papers: Measuring Black Hole Spin in OJ287
We present a summary of the results of the OJ 287 observational campaign, which was carried out during the 2021/2022 observational season. This season is special in the binary model because the major axis of the precessing binary happens to…
Gravitational wave (GW) measurements provide the most robust constraints of the mass of astrophysical black holes. Using state-of-the-art GW signal models and a unique parameter estimation technique, we infer the source parameters of the…
Theoretical studies of angular momentum transport suggest that isolated stellar-mass black holes are born with negligible dimensionless spin magnitudes $\chi \lesssim 0.01$. However, recent gravitational-wave observations indicate $\gtrsim…
We consider a subset of the physical processes that determine the spin j = a/M of astrophysical black holes. These include: (1) Initial conditions. Recent models suggest that the collapse of supermassive stars are likely to produce black…
Accretion disk reflection spectra, including broad iron emission lines, bear the imprints of the strong Doppler shifts and gravitational red-shifts close to black holes. The extremity of these shifts depends on the proximity of the…
We used two numerical models, namely the \texttt{CBwaves} and \texttt{SEOBNRE} algorithms, based on the post-Newtonian and effective-one-body approaches for binary black holes evolving on eccentric orbits. We performed 20.000 new…
A gravitational wave (GW) signal carries imprints of the properties of its source. The ability to extract source properties crucially depends on our prior knowledge of the signal morphology. Even though binary black hole (BBH) mergers are…
The evolution of the spin and tilt of black holes in compact black hole - neutron star and black hole - black hole binary systems is investigated within the framework of the coalescing compact star binary model for short gamma ray bursts…
The black hole masses measured from gravitational wave observations appear to cluster around specific mass values. Consequently, the primary~(and chirp) mass distribution of binary black holes inferred using these measurements shows four…
We present a spectral analysis of \textit{Insight}-HXMT observations of the low-mass X-ray binary 4U 1543-47 which locates in our Milky Way galaxy during the 2021 outburst. We focus on the observations in its soft state, and attempt to…
We report the results from \textit{AstroSat} observations of the transient Galactic black hole X-ray binary MAXI J1535-571 during its hard-intermediate state of the 2017 outburst. We systematically study the individual and joint spectra…
We revisit the modeling of the properties of the remnant black hole resulting the merger of a black-hole binary as a function of the parameters of the binary. We provide a set of empirical formulas for the final mass, spin and recoil…
Now that the mass of the central black hole in the galaxy M87 has been measured with great precision using different methods, the remaining parameter of the Kerr metric that needs to be estimated is the spin a*. We have modeled measurements…
The development of techniques to measure accurately black hole spins is crucial to study the physics and astrophysics of these objects. X-ray reflection spectroscopy is currently the most popular method to estimate the spins of accreting…
We present three simultaneous/quasi-simultaneous NuSTAR and Swift datasets of the black hole GRS 1716-249 in its hard intermediate state. The accretion disk in this state may have reached the innermost stable circular orbit, and the NuSTAR…
The 136 year long optical light curve of OJ~287 is explained by a binary black hole model where the secondary is in a 12 year orbit around the primary. Impacts of the secondary on the accretion disk of the primary generate a series of…
The motion of classical spinning test particles in the equatorial plane of a Kerr black hole is considered for the case where the particle spin is perpendicular to the equatorial plane. We review some results of our recent research of the…
In a previous work, we have identified the spin of the dominant black hole of a binary from its jet properties. Analysing Very Long Baseline Array (VLBA) observations of the quasar S5~1928+738, taken at $15$-GHz during $43$ epochs between…
We report the results of a comprehensive analysis of the multiwavelength (in optical and X-rays) and multitimescale (from months to tenths of a second) variability of the 2018-2020 outburst of the black hole transient MAXI J1820+070. During…
There is robust observational evidence supporting the existence of $5 - 20$ $M_\odot$ compact bodies in X-ray binary systems and of $10^5 - 10^9$ $M_\odot$ bodies at the center of many galaxies. All these objects are commonly interpreted as…