OGLE-2011-BLG-0462: An Isolated Stellar-Mass Black Hole Confirmed Using New HST Astrometry and Updated Photometry

Abstract

The long-duration Galactic-bulge microlensing event OGLE-2011-BLG-0462 produced relativistic astrometric deflections of the source star, which we measured using HST observations taken at 8 epochs over ~6 years. Analysis of the microlensing light curve and astrometry led our group (followed by other independent groups) to conclude that the lens is an isolated stellar-mass black hole (BH) -- the first and only one unambiguously discovered to date. There have now been three additional epochs of HST observations, increasing the astrometric time baseline to 11 years. Additionally, the ground-based OGLE data have been updated. We have re-analyzed the data, including the new HST astrometry, and photometry obtained with 16 different telescopes. The source lies only 0.4 arcsec from a bright neighbor, making it crucial to perform precise subtraction of its point-spread function (PSF) in the astrometric measurements of the source. Moreover, we show that it is essential to perform a separate PSF subtraction for each individual HST frame as part of the reductions. Our final solution yields a lens mass of 7.15 +/- 0.83 solar mass. Combined with the lack of detected light from the lens at late HST epochs, the BH nature of the lens is conclusively verified. The BH lies at a distance of 1.52 +/- 0.15 kpc, and is moving with a space velocity of 51.1 +/- 7.5 km/s relative to the stars in the neighborhood. We compare our results with those of other studies and discuss reasons for the differences. We searched for binary companions of the BH at a range of separations but found no evidence for any.

17 pages, 8 figures, to appear in Astrophysical Journal. Updated version with minor edits and revisions

References in corpus (14)

• Gaia Data Release 3: Summary of the content and survey properties
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. V. Evidence for a wide age distribution and a complex MDF
• A Sun-like star orbiting a black hole
• A red giant orbiting a black hole
• The State-of-the-Art HST Astro-Photometric Analysis of the core of $\omega$ Centauri. I. The Catalog
• An isolated mass gap black hole or neutron star detected with astrometric microlensing
• Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry
• A non-interacting Galactic black hole candidate in a binary system with a main-sequence star
• Systematic errors as a source of mass discrepancy in black hole microlensing event OGLE-2011-BLG-0462
• Wide binary companions to massive stars and their use in constraining natal kicks
• Very wide companion fraction from Gaia DR2: a weak or no enhancement for hot jupiter hosts, and a strong enhancement for contact binaries
• The Interstellar Extinction Toward the Milky Way Bulge with Planetary Nebulae, Red Clump, and RR Lyrae stars
• On the Possibility of Direct Detection of the Emission of Microlens MOA-2011-BLG-191/OGLE-2011-BLG-0462 -- a Probable Black Hole

Cited by in corpus (5)

• Natal kicks of compact objects
• Probing the detectability of electromagnetic signatures from Galactic isolated black holes
• Detection Prospects of Electromagnetic Signatures from OGLE-2011-BLG-0462
• "Industrial-Scale" Black Hole Selection without a Satellite
• Empirical correlation between masses of black holes and Wolf-Rayet stars derived from their mass distributions in spectroscopic binaries