At https://phys.org/news/2023-03-light-bending-gravity-reveals-biggest-black.html … a team of astronomers claim to have discovered one of the biggest black holes known – taking advantage of gravitational lensing. This involves a foreground galaxy bending the light from a more distant object and magnifying it. Super computer simulation enabled the team to closely examine how light is bent by a black hole inside a galaxy hundred of millions of miles away. The team simulated light travelling through the universe. When the simulation included a supermassive black hole it was used to capture an image in the Hubble Space Telescope. Gravitational lensing makes it possible to study inactive black holes.
At https://phys.org/news/2023-03-astronomers-x-ray-binary-xte-j1739285.html … the AstroSat and NuSTAR space telescopes were used to observe an X-ray binary, XTE J1739-285 during a burst of activity. The results are on the arXiv pre-print server [see https://doi.org/10.48550/arxiv.2303.13085 ]. X-ray binaries are thought to consist of a normal star, or a white dwarf, transferring mass onto a compacted neutron star – or into a black hole.
Some then exhibit transient outbursts during which there is an increase in X-ray luminosities. Type One X-ray burst are thought to be thermonuclear explosions on the surface layer of neutron stars. They obviously confirm the presence of neutron stars in such binaries, we are told.