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Double compact objects (neutron stars and black holes) found in binaries with small orbital separations are known to spiral in and are expected to coalesce eventually because of the emission of gravitational waves. Such inspiral and merger…
LIGO and Virgo have reported the detection of GW190521, from the merger of a binary black hole (BBH) with a total mass around $150$ M$_\odot$. While current stellar models limit the mass of any black hole (BH) remnant to about $40 - 50$…
GRB 211211A is a rare burst with a genuinely long duration, yet its prominent kilonova association provides compelling evidence that this peculiar burst was the result of a compact binary merger. However, the exact nature of the merging…
The origin of the black hole (BH) binary mergers observed by LIGO-Virgo is still uncertain, as are the boundaries of the stellar BH mass function. Stellar evolution models predict a dearth of BHs both at masses $\gtrsim 50$ M$_\odot$ and…
In a dense stellar environment, such as the core of a globular cluster (GC), dynamical interactions with black holes (BHs) are expected to lead to a variety of astrophysical transients. Here we explore tidal disruption events (TDEs) of…
The recent discovery by LIGO/Virgo of a merging binary having a $\sim 23 M_\odot$ black hole and a $\sim 2.6 M_\odot$ compact companion has triggered a debate regarding the nature of the secondary, which falls into the so-called mass gap.…
I study the contribution of young massive star clusters (YMCs) and open star clusters (OCs) to the present-day intrinsic merger rate density of dynamically-assembled binary black holes (BBHs). The BBH merger event rate is estimated based on…
The gravitational wave detectors have unveiled a population of massive black holes that do not resemble those observed in the Milky Way and whose origin is debated. According to one possible explanation, these black holes may have formed…
The advanced LIGO O3a run catalog has been recently published, and it includes several events with unexpected mass properties, including mergers with individual masses in the lower and upper mass gaps, as well as mergers with unusually…
The primary and secondary masses of the binary black holes (BBH) reported by LIGO/Virgo are correlated with a narrow dispersion that appears to increase in proportion to mass. The mean binary mass ratio $1.45\pm0.07$ we show is consistent…
We investigate secular evolution in hierarchical quadruple systems as a formation channel of mass-gap black holes (with masses of about $3-5$ $M_{\odot}$) in systems that will eventually lead to binary black hole mergers detectable by…
We consider the merging of high-mass black-hole binaries of the Cyg X-1 type, in which the O-star companion becomes a neutron star following a supernova explosion. Our estimated rate of mergers, $\sim 2\times 10^{-5} yr^{-1}$ for the…
The recently published GWTC-1 - a journal article summarizing the search for gravitational waves (GWs) from coalescing compact binaries in data produced by the LIGO-Virgo network of ground-based detectors during their first and second…
Modern surveys of gravitational microlensing events have progressed to detecting thousands per year. Surveys are capable of probing Galactic structure, stellar evolution, lens populations, black hole physics, and the nature of dark matter.…
Intermediate mass black holes (IMBHs) may be the link between stellar mass holes and the supermassive variety in the nuclei of galaxies, and globular clusters (GCs) may be one of the most promising environments for their formation. Here we…
On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. Preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH…
The latest detection of GW231123, a binary black hole (BH) merger with exceptionally large masses and high spins for the incoming components, has been suggested as a smoking gun for hierarchical formation. In this scenario, a first…
We report the detection of new binary black hole merger events in the publicly available data from the second observing run of advanced LIGO and advanced Virgo (O2). The mergers were discovered using the new search pipeline described in…
Version 5.0 of the Gravitational-Wave Transient Catalog (GWTC-5.0) adds new candidates detected by the LIGO Virgo KAGRA network of observatories through the second part of the fourth observing run (O4b: 2024 April 10 15:00:00 to 2025…
In this work we take our cue from the observations of gravitational waves of the GW190814 event which suggests that source of the signals can be ascribed to a compact binary coalescence of a 22.2 to 24.3$ M_{\odot}$ black hole and a compact…