Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions

Abstract In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample of nine microlensing events, selected based on their long timescales, small microlensing parallaxes, and joint observations by the Gaia mission, to increase the probability that the chosen lenses are massive and the mass is measurable. Among the selected events we identify lensing black holes and neutron star candidates, with potential confirmation through forthcoming release of the Gaia time-series astrometry in 2026. Utilizing Bayesian analysis and Galactic models, along with the Gaia Data Release 3 proper-motion data, four good candidates for dark remnants were identified: OGLE-2016-BLG-0293, OGLE-2018-BLG-0483, OGLE-2018-BLG-0662, and OGLE-2015-BLG-0149, with lens masses of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>3.0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.8</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>4.7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.2</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>3.15</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.64</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.66</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>1.40</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.55</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.75</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> , respectively. Notably, the first two candidates are expected to exhibit astrometric microlensing signals detectable by Gaia, offering the prospect of validating the lens masses. The methodologies developed in this work will be applied to the full Spitzer microlensing sample, populating and analyzing the timescale ( t E ) versus parallax ( π E ) diagram to derive constraints on the population of lenses in general and massive remnants in particular.

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Publication Details

Journal
The Astrophysical Journal
Published
2024-11-01
DOI
https://doi.org/10.3847/1538-4357/ad7bb1
Citations
4
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
1.33

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article

Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions

Sang-Mok Cha, Yongseok Lee, I. Soszyński, Michael D. Albrow et al.
4 citations
The Astrophysical Journal
Stellar, planetary, and galactic studies
1.33
article

Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions

Sang-Mok Cha, Yongseok Lee, I. Soszyński, Michael D. Albrow, Weicheng Zang, Hongjing Yang, Yuki Satoh, Y. Itow, K. Howil, Ł. Wyrzykowski, T. Nagai, Kyu‐Ha Hwang, Akihiko Fukui, Richard Barry, Hibiki Yama, ‪Clément Ranc, Charles Beichman, Naoto Hamasaki, Y. Muraki, Krzysztof A. Rybicki, G. Bryden, D. P. Bennett, M. K. Szymański, J. Skowron, Byeong-Gon Park, R. Poleski, Yoon-Hyun Ryu, Wei Zhu, Yossi Shvartzvald, Seung‐Lee Kim, Chung‐Uk Lee, Rintaro Kirikawa, Dong-Joo Lee, Aparna Bhattacharya, Calen B. Henderson, Naoki Koshimoto, Sun‐Ju Chung, Cheongho Han, Aikaterini Vandorou, A. Udalski, Michael Fausnaugh, Youn Kil Jung, Patryk Iwanek, Stela Ishitani Silva, I. A. Bond, P. Pietrukowicz, P. Mróz, S. Calchi Novati, K. Ulaczyk, Nicholas J. Rattenbury, Hyoun-Woo Kim, Ryusei Hamada, K. Kruszyńska, In-Gu Shin, Greg Olmschenk, E. O. Ofek, Yuki Hirao, Jennifer C. Yee, Benjamin D. Wibking, S. Carey, Y. Matsubara, Dong-Jin Kim, P. J. Tristram, S. Kozłowski, Richard W. Pogge, Marcin Wrona, Kansuke Nunota, Shota Miyazaki, Takahiro Sumi, Daisuke Suzuki, Fumio Abe, Shunya Hamada, Andrew Gould
article en
4 citations

Abstract

Abstract In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample of nine microlensing events, selected based on their long timescales, small microlensing parallaxes, and joint observations by the Gaia mission, to increase the probability that the chosen lenses are massive and the mass is measurable. Among the selected events we identify lensing black holes and neutron star candidates, with potential confirmation through forthcoming release of the Gaia time-series astrometry in 2026. Utilizing Bayesian analysis and Galactic models, along with the Gaia Data Release 3 proper-motion data, four good candidates for dark remnants were identified: OGLE-2016-BLG-0293, OGLE-2018-BLG-0483, OGLE-2018-BLG-0662, and OGLE-2015-BLG-0149, with lens masses of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>3.0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.8</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>4.7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.2</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>3.15</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.64</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.66</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>1.40</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.55</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.75</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> , respectively. Notably, the first two candidates are expected to exhibit astrometric microlensing signals detectable by Gaia, offering the prospect of validating the lens masses. The methodologies developed in this work will be applied to the full Spitzer microlensing sample, populating and analyzing the timescale ( t E ) versus parallax ( π E ) diagram to derive constraints on the population of lenses in general and massive remnants in particular.

The Astrophysical JournalVol. 975(2)
California Institute of Technology (US), Texas Tech University (US), Las Cumbres Observatory Global Telescope Network (US), Centre National de la Recherche Scientifique (FR), Goddard Space Flight Center (US), University of Auckland (NZ), Chungbuk National University (KR), University of America (US), University of Canterbury (NZ), Kanto Gakuin University (JP), Korea Astronomy and Space Science Institute (KR), Japan Aerospace Exploration Agency (JP), Institut d'Astrophysique de Paris (FR), Kyung Hee University (KR), University of Warwick (GB), Sorbonne Université (FR), Max Planck Institute for Astronomy (DE), Center for Astrophysics Harvard & Smithsonian (US), Instituto de Astrofísica de Canarias (ES), Institute of Space and Astronautical Science (JP), Infrared Processing and Analysis Center (US), University of Warsaw (PL), Massey University (NZ), The Ohio State University (US), Weizmann Institute of Science (IL), Nagoya University (JP), University of Maryland, College Park (US), The University of Tokyo (JP), Catholic University of America (US), Michigan State University (US), Korea University of Science and Technology (KR), The University of Osaka (JP), Tsinghua University (CN)
National Science Foundation, Smithsonian Institution, National Research Foundation, Weizmann Institute of Science, National Natural Science Foundation of China, Korea Astronomy and Space Science Institute, National Research Foundation of Korea, Council for Higher Education, Ministry of Science and ICT, South Korea, Korea Research Environment Open Network, Smithsonian Astrophysical Observatory, Japan Society for the Promotion of Science
Openalex Percentile: Top 19%
Stellar, planetary, and galactic studies
1.33
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