TY - JOUR AU - Cappelluti, Nico AU - Pacucci, Fabio AU - Hasinger, Günther Gustav TI - Constraining Wind-driven Accretion onto Gaia BH3 with Chandra JO - The astrophysical journal / Part 1 VL - 973 IS - 2 SN - 0004-637X CY - London PB - Institute of Physics Publ. M1 - PUBDB-2024-07605 M1 - arXiv:2406.07602 SP - 75 PY - 2024 N1 - Accepted for publication in The Astrophysical Journal. 10 pages, 4 figures AB - Gaia BH3 is the most massive known stellar-origin black hole in the Milky Way, with a mass M<sub>•</sub> ≈ 33 M<sub>⊙</sub>. Detected from Gaia’s astrometry, this black hole is in the mass range of those observed via gravitational waves, whose nature is still highly debated. Hosted in a binary system with a companion giant star that is too far away for Roche-lobe mass transfer, this black hole could nonetheless accrete at low levels due to wind-driven mass loss from its companion star, thus accreting in advection-dominated accretion flow, or ADAF, mode. Using stellar wind models, we constrain its Eddington ratio in the range 10<sup>−9</sup> < f<sub>Edd</sub> < 10<sup>−7</sup>, corresponding to radiative efficiencies 5 × 10<sup>−5</sup> < ϵ < 10<sup>−3</sup>, compatible with radiatively inefficient accretion modes. Chandra ACIS-S observed this object and obtained the most sensitive upper bound of its [2–10] keV flux: F<sub>X</sub> < 3.25 × 10<sup>−15</sup> erg s<sup>−1</sup> cm<sup>−2</sup> at 90 LB - PUB:(DE-HGF)16 UR - <Go to ISI:>//WOS:001317245800001 DO - DOI:10.3847/1538-4357/ad6f96 UR - https://bib-pubdb1.desy.de/record/619400 ER -