A Binary Origin for the First Isolated Stellar-mass Black Hole Detected with Astrometric Microlensing
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A Binary Origin for the First Isolated Stellar-mass Black Hole Detected with Astrometric Microlensing. / Vigna-Gomez, Alejandro; Ramirez-Ruiz, Enrico.
I: Astrophysical Journal Letters, Bind 946, Nr. 1, 2, 01.03.2023.Publikation: Bidrag til tidsskrift › Letter › Forskning › fagfællebedømt
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TY - JOUR
T1 - A Binary Origin for the First Isolated Stellar-mass Black Hole Detected with Astrometric Microlensing
AU - Vigna-Gomez, Alejandro
AU - Ramirez-Ruiz, Enrico
PY - 2023/3/1
Y1 - 2023/3/1
N2 - The Milky Way is believed to host hundreds of millions of quiescent stellar-mass black holes (BHs). In the last decade, some of these objects have been potentially uncovered via gravitational microlensing events. All these detections resulted in a degeneracy between the velocity and the mass of the lens. This degeneracy has been lifted, for the first time, with the recent astrometric microlensing detection of OB110462. However, two independent studies reported very different lens masses for this event. Sahu et al. inferred a lens mass of 7.1 +/- 1.3 M (circle dot), consistent with a BH, while Lam et al. inferred 1.6-4.2 M (circle dot), consistent with either a neutron star or a BH. Here, we study the landscape of isolated BHs formed in the field. In particular, we focus on the mass and center-of-mass speed of four subpopulations: isolated BHs from single-star origin, disrupted BHs of binary-star origin, main-sequence stars with a compact object companion, and double compact object mergers. Our model predicts that most (greater than or similar to 70%) isolated BHs in the Milky Way are of binary origin. However, noninteractions lead to most massive BHs (greater than or similar to 15-20 M (circle dot)) being predominantly of single origin. Under the assumption that OB110462 is a free-floating compact object, we conclude that it is more likely to be a BH originally belonging to a binary system. Our results suggest that low-mass BH microlensing events can be useful to understand binary evolution of massive stars in the Milky Way, while high-mass BH lenses can be useful to probe single stellar evolution.
AB - The Milky Way is believed to host hundreds of millions of quiescent stellar-mass black holes (BHs). In the last decade, some of these objects have been potentially uncovered via gravitational microlensing events. All these detections resulted in a degeneracy between the velocity and the mass of the lens. This degeneracy has been lifted, for the first time, with the recent astrometric microlensing detection of OB110462. However, two independent studies reported very different lens masses for this event. Sahu et al. inferred a lens mass of 7.1 +/- 1.3 M (circle dot), consistent with a BH, while Lam et al. inferred 1.6-4.2 M (circle dot), consistent with either a neutron star or a BH. Here, we study the landscape of isolated BHs formed in the field. In particular, we focus on the mass and center-of-mass speed of four subpopulations: isolated BHs from single-star origin, disrupted BHs of binary-star origin, main-sequence stars with a compact object companion, and double compact object mergers. Our model predicts that most (greater than or similar to 70%) isolated BHs in the Milky Way are of binary origin. However, noninteractions lead to most massive BHs (greater than or similar to 15-20 M (circle dot)) being predominantly of single origin. Under the assumption that OB110462 is a free-floating compact object, we conclude that it is more likely to be a BH originally belonging to a binary system. Our results suggest that low-mass BH microlensing events can be useful to understand binary evolution of massive stars in the Milky Way, while high-mass BH lenses can be useful to probe single stellar evolution.
KW - COMMON ENVELOPE EVOLUTION
KW - NEUTRON-STAR
KW - CORE-COLLAPSE
KW - O-STARS
KW - METALLICITY
KW - SUPERNOVAE
KW - KICKS
KW - PROGENITORS
KW - DEPENDENCE
KW - PROSPECTS
U2 - 10.3847/2041-8213/acc076
DO - 10.3847/2041-8213/acc076
M3 - Letter
VL - 946
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - 2
ER -
ID: 341918739