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Measuring the mass function of isolated stellar remnants with gravitational microlensing. II. Analysis of the OGLE-III data

Mróz, Przemek and Udalski, Andrzej and Wyrzykowski, Łukasz and Skowron, Jan and Poleski, Radosław and Szymanski, Michał K. and Soszyński, Igor and Ulaczyk, Krzysztof (2021) Measuring the mass function of isolated stellar remnants with gravitational microlensing. II. Analysis of the OGLE-III data. . (Unpublished)

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Our knowledge of the birth mass function of neutron stars and black holes is based on observations of binary systems but the binary evolution likely affects the final mass of the compact object. Gravitational microlensing allows us to detect and measure masses of isolated stellar remnants, which are nearly impossible to obtain with other techniques. Here, we analyze a sample of 4360 gravitational microlensing events detected during the third phase of the OGLE survey. We select a subsample of 87 long-timescale low-blending events. We estimate the masses of lensing objects by combining photometric data from OGLE and proper-motion information from OGLE and Gaia EDR3. We find 35 high-probability dark lenses - white dwarfs, neutron stars, and black holes - which we use to constrain the mass function of isolated stellar remnants. In the range 1-100 M_⊙, occupied by neutron stars and black holes, the remnant mass function is continuous and can be approximated as a power-law with a slope of 0.83^(+0.16)_(−0.18) with a tentative evidence against a broad gap between neutron stars and black holes. This slope is slightly flatter than the slope of the mass function of black holes detected by gravitational wave detectors LIGO and Virgo, although both values are consistent with each other within the quoted error bars. The measured slope of the remnant mass function agrees with predictions of some population synthesis models of black hole formation.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Mróz, Przemek0000-0001-7016-1692
Udalski, Andrzej0000-0001-5207-5619
Wyrzykowski, Łukasz0000-0002-9658-6151
Skowron, Jan0000-0002-2335-1730
Poleski, Radosław0000-0002-9245-6368
Szymanski, Michał K.0000-0002-0548-8995
Soszyński, Igor0000-0002-7777-0842
Ulaczyk, Krzysztof0000-0001-6364-408X
Additional Information:We thank Jim Fuller, Ilya Mandel, and Aleksandra Olejak for discussions and their comments on the manuscript. This work benefited from help of Krzysztof Rybicki, Katarzyna Kruszyńska, as well as students at the Astronomical Observatory, University of Warsaw, particularly: Zofia Kaczmarek, Kornel Howil, Mateusz Bronikowski, and Anna Jabłonowska. P.M. acknowledges the support from Heising-Simons Foundation Grant #2018-1036 awarded to J. Fuller. Ł.W. acknowledges the support from the Polish National Science Center grants: Harmonia No. 2018/30/M/ST9/00311 and Daina No. 2017/27/L/ST9/03221.
Funding AgencyGrant Number
Heising-Simons Foundation2018-1036
National Science Centre (Poland)2018/30/M/ST9/00311
National Science Centre (Poland)2017/27/L/ST9/03221
Classification Code:Gravitational microlensing (672), Stellar remnants (1627), Black holes (162), Neutron stars (1108), White dwarf stars (1799)
Record Number:CaltechAUTHORS:20211217-233141433
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112529
Deposited By: George Porter
Deposited On:20 Dec 2021 19:21
Last Modified:20 Dec 2021 19:21

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