Black hole binaries with extreme (≳ 10 4: 1) or intermediate (∼ 10 2–10 4: 1) mass ratios
are among the most interesting gravitational wave sources that are expected to be detected …

Today's sensitive X-ray observations allow the study of populations of X-ray binaries in
galaxies as distant as 20–30 Mpc. Photometric diagrams and luminosity functions applied to …

The astrophysical origin of gravitational wave (GW) events discovered by LIGO/VIRGO
remains an outstanding puzzle. In active galactic nuclei (AGNs), compact-object binaries …

Studying the formation and evolution of black hole binaries (BHBs) is essential for the
interpretation of current and forthcoming gravitational wave (GW) detections. We investigate …

The first four gravitational wave events detected by LIGO were all interpreted as merging
black hole binaries (BHBs), opening a new perspective on the study of such systems. Here …

Nuclear star clusters around a central massive black hole (MBH) are expected to be
abundant in stellar black hole (BH) remnants and BH–BH binaries. These binaries form a …

The environment near supermassive black holes (SMBHs) in galactic nuclei contains a large
number of stars and compact objects. A fraction of these are likely to be members of …

We present the analysis of five black hole candidates identified from gravitational
microlensing surveys. Hubble Space Telescope astrometric data and densely sampled light …

The cosmic merger rate density of black hole binaries (BHBs) can give us an essential clue
to constraining the formation channels of BHBs, in light of current and forthcoming …

Nuclear star clusters surrounding supermassive black holes (SMBHs) in galactic nuclei
contain large numbers of stars, black holes (BHs), and neutron stars (NSs), a fraction of …