2025MNRAS.541.3709M

OGLE-2011-BLG-0462 is an isolated black hole of $\sim 7\, {\rm M}_{\odot }$ at a distance of 1.5 kpc identified thanks to the astrometric microlensing technique. It is the first specimen discovered of the large population of $\sim 10^8$ stellar-mass black holes that are believed to wander in the Galaxy. Electromagnetic radiation powered by accretion from the interstellar medium is expected from OGLE-2011-BLG-0462, but has not been detected at any wavelength. We present the results of a deep pointed observation with the Chandra satellite that provides an upper limit of $3\times 10^{29}$ erg s$^{-1}$ on the luminosity of OGLE-2011-BLG-0462 in the 0.5-7 keV energy range. This is about one order of magnitude below the previous limit obtained from shallower observations that serendipitously covered the sky position of this black hole. Our results are briefly compared with models of the source and with the X-ray upper limits for candidate isolated black holes and black holes in wide binary systems.