Sahu, KC, Anderson, J, Casertano, S, Bond, HE, Udalski, A, Dominik, M, Calamida, A, Bellini, A, Brown, TM, Rejkuba, M, Bajaj, V, Kains, N, Ferguson, HC, Fryer, CL, Yock, P, Mroz, P, Kozlowski, S, Pietrukowicz, P, Poleski, R, Skowron, J, Soszynski, I, Szymanski, MK, Ulaczyk, K, Wyrzykowski, L, Beaulieu, J-P, Marquette, J-B, Cole, A, Hill, K, Dieters, S, Coutures, C, Dominis-Prester, D, Bachelet, E, Menzies, J, Albrow, M, Pollard, K, Gould, A, Yee, J, Allen, W, Almeida, LAD, Christie, G, Drummond, J, Gal-Yam, A, Gorbikov, E, Jablonski, F, Lee, C-U, Maoz, D, Manulis, I, McCormick, J, Natusch, T, Pogge, RW, Shvartzvald, Y, Jorgensen, UG, Alsubai, KA, Andersen, MI, Bozza, V, Novati, SC, Hinse, TC, Hundertmark, M, Husser, T-O, Kerins, E, Longa-Pena, P, Mancini, L, Penny, M, Rahvar, S, Ricci, D, Sajadian, S, Skottfelt, J, Snodgrass, C, Southworth, J, Tregloan-Reed, J, Wambsganss, J, Wertz, O, Tsapras, Y, Street, RA, Bramich, DM, Horne, K and Steele, IA (2022) An Isolated Stellar-Mass Black Hole Detected Through Astrometric Microlensing. ISSN 0004-6256 (Unpublished)

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We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration (t_E ~ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462, in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of six years, reveals a clear relativistic astrometric deflection of the background star's apparent position. Ground-based photometry shows a parallactic signature of the effect of the Earth's motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 +/- 1.3 M_Sun and a distance of 1.58 +/- 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic-disk stars at similar distances by an amount corresponding to a transverse space velocity of ~45 km/s, suggesting that the BH received a modest natal 'kick' from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial-velocity measurements of Galactic X-ray binaries, and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first ever for an isolated stellar-mass BH using any technique.

Item Type: Article
Additional Information: This is a preprint server article. Any information and copyright requirements can be found on the website.
Subjects: Q Science > QB Astronomy
Q Science > QB Astronomy > QB460 Astrophysics
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 16 Feb 2022 16:13
Last Modified: 16 Feb 2022 16:13

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