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An Isolated Stellar-mass Black Hole Detected through Astrometric Microlensing

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posted on 2023-05-21, 15:43 authored by 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, A, Barry, RK, Bennett, DP, Bond, IA, Hirao, Y, Silva, SI, Kondo, I, Koshimoto, N, Ranc, C, Rattenbury, NJ, Sumi, T, Suzuki, D, Tristram, PJ, Vandorou, A, Jean-Philippe BeaulieuJean-Philippe Beaulieu, Marquette, JB, Andrew ColeAndrew Cole, Fouque, P, Kym HillKym Hill, Dieters, S, Christian Coutures, Dominis-Prester, D, Bennett, C, Bachelet, E, Menzies, J, Albrow, M, Pollard, K, Gould, A, Yee, JC, Allen, W, Allen, LA, Christie, G, Drummond, J, Gal-Yam, A, Gorbikov, E, Jablonski, F, Lee, CU, Maoz, D, Manulis, I, McCormick, J, Natusch, T, Pogge, RW, Shvartzvald, Y, Jorgensen, UG, Alsubai, KA, Andersen, MI, Bozza, V, Novati, SC, Burgdorf, M, Hinse, TC, Hundertmark, M, Husser, TO, 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, Steele, IA
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 (tE ≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of 6 yr, reveals a clear relativistic astrometric deflection of the background star's apparent position. Ground-based photometry of MOA-11-191/OGLE-11-462 shows a parallactic signature of the effect of 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⊙ 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−1, suggesting that the BH received a "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 for an isolated stellar-mass BH using any technique.

Funding

Australian Research Council

History

Publication title

Astrophysical Journal

Volume

933

Article number

83

Number

83

Pagination

1-28

ISSN

0004-637X

Department/School

School of Natural Sciences

Publisher

Institute of Physics Publishing, Inc.

Place of publication

1427 E 60Th St, Chicago, USA, Il, 60637-2954

Rights statement

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, https://creativecommons.org/licenses/by/4.0/.

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  • Open

Socio-economic Objectives

Expanding knowledge in the physical sciences

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