Supplement: “An Isolated Mass-gap Black Hole or Neutron Star Detected with Astrometric Microlensing” (2022, ApJL, 933, L23)

Lam, Casey; Lu, Jessica R.; Udalski, A.; Bond, I. A.; Bennett, D. P.; Skowron, J.; Mróz, P.; Poleski, R.; Sumi, T.; Szymański, M. K.; Kozłowski, S.; Pietrukowicz, P.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Miyazaki, Shota; Suzuki, D.; Koshimoto, Naoki; Rattenbury, N. J.; Hosek, Matthew W.; Abe, F.; Barry, Richard; Bhattacharya, Aparna; Fukui, A.; Fujii, Hirosane; Hirao, Yuki; Itow, Y.; Kirikawa, Rintaro; Kondo, Iona; Matsubara, Y.; Matsumoto, Sho; Muraki, Y.; Olmschenk, Greg; Ranc, Clément; Okamura, Arisa; Satoh, Yuki; Silva, Stela Ishitani; Toda, Taiga; Tristram, P. J.; Vandorou, Aikaterini; Yama, Hibiki; Abrams, Natasha S.; Agarwal, Shrihan; Rose, Sam; Terry, Sean K.

doi:10.3847/1538-4365/ac7441

Cited by 4 publications

(40 citation statements)

References 83 publications

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“…Sahu et al (2022) inferred the lens to be a M L = 7.1 ± 1.3 M e dark object, making OB110462 a firm BH detection similar in mass to other known Galactic BHs in binary systems. Lam et al (2022aLam et al ( , 2022b dark object, implying a neutron star or low-mass BH. Both groups analyzed slightly different subsets of high-cadence ground-based photometry and high-resolution Hubble Space Telescope (HST) astrometry; see Mróz et al (2022) for a summary.…”

Section: An Isolated Dark Compact Object Found With Microlensingmentioning

confidence: 99%

“…Eleven epochs of HST observations of OB110462 were obtained between 2011 and 2022, and are presented in Table 1. This includes all the data analyzed in Lam et al (2022aLam et al ( , 2022b see Table 2 in Lam et al 2022b), with several additions. First, all exposures taken on 2011 August 8 were included in this analysis (compared to Lam et al 2022aLam et al , 2022b, who excluded three frames that had different exposure times than the main data set).…”

Section: Hstmentioning

confidence: 99%

“…This includes all the data analyzed in Lam et al (2022aLam et al ( , 2022b see Table 2 in Lam et al 2022b), with several additions. First, all exposures taken on 2011 August 8 were included in this analysis (compared to Lam et al 2022aLam et al , 2022b, who excluded three frames that had different exposure times than the main data set). The exposures from 2013 May 13 were also included (compared to Lam et al 2022aLam et al , 2022b, who excluded them because there were no other spring epochs to calibrate them, resulting in reference frame alignment issues due to parallax; however there is now a second spring epoch that can be used to perform this calibration).…”

Section: Hstmentioning

confidence: 99%

“…It is described in Anderson & King (2006), and although it has been updated and used in many publications over the years, it was never formally released as Space Telescope Science Institute-supported software. Lam et al (2022aLam et al ( , 2022b and Sahu et al (2022) used one of these unofficial hst1pass releases to perform their astrometric analyses.…”

Section: Updated Astrometric Reductions and Analysis With Hst1passmentioning

confidence: 99%

“…This neighbor star biases the measurement of the flux and position of OB110462. Lam et al (2022aLam et al ( , 2022b and Sahu et al (2022) took different approaches to calculate this bias. Sahu et al (2022) used 18 nearby isolated stars with colors and magnitudes comparable to the neighbor to construct an "extended model" point-spread function (PSF).…”

Section: Artificial Star Injection-and-recovery Testsmentioning

confidence: 99%

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A Reanalysis of the Isolated Black Hole Candidate OGLE-2011-BLG-0462/MOA-2011-BLG-191

Lam,

2023

ApJ

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There are expected to be ∼108 isolated black holes (BHs) in the Milky Way. OGLE-2011-BLG-0462/MOA-2011-BLG-191 (OB110462) is the only such BH with a mass measurement to date. However, its mass is disputed: Lam et al. measured a lower mass of 1.6–4.4 M ⊙, while Sahu et al. and Mróz et al. measured a higher mass of 5.8–8.7 M ⊙. We reanalyze OB110462, including new data from the Hubble Space Telescope (HST) and rereduced Optical Gravitational Lensing Experiment (OGLE) photometry. We also rereduce and reanalyze the HST data set with newly available software. We find significantly different (∼1 mas) HST astrometry than Lam et al. in the unmagnified epochs due to the amount of positional bias induced by a bright star ∼0.″4 from OB110462. After modeling the updated photometric and astrometric data sets, we find the lens of OB110462 is a 6.0 − 1.0 + 1.2 M ⊙ BH. Future observations with the Nancy Grace Roman Space Telescope, which will have an astrometric precision comparable or better to HST but a field of view 100× larger, will be able to measure hundreds of isolated BH masses via microlensing. This will enable the measurement of the BH mass distribution and improve understanding of massive stellar evolution and BH formation channels.

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Section: An Isolated Dark Compact Object Found With Microlensingmentioning

confidence: 99%

Section: Hstmentioning

confidence: 99%

Section: Hstmentioning

confidence: 99%

Section: Updated Astrometric Reductions and Analysis With Hst1passmentioning

confidence: 99%

Section: Artificial Star Injection-and-recovery Testsmentioning

confidence: 99%

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A Reanalysis of the Isolated Black Hole Candidate OGLE-2011-BLG-0462/MOA-2011-BLG-191

Lam,

2023

ApJ

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Astrometric weak lensing with Gaia DR3 and future catalogues: searches for dark matter substructure

Mondino,

Tsantilas,

Taki

et al. 2024

Monthly Notices of the Royal Astronomical Society

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Small-scale dark matter structures lighter than a billion solar masses are an important probe of primordial density fluctuations and dark matter microphysics. Due to their lack of starlight emission, their only guaranteed signatures are gravitational in nature. We report on results of a search for astrometric weak lensing by compact dark matter subhalos in the Milky Way with Gaia DR3 data. Using a matched-filter analysis to look for correlated imprints of time-domain lensing on the proper motions of background stars in the Magellanic Clouds, we exclude order-unity substructure fractions in halos with masses Ml between 107 M⊙ and 109 M⊙ and sizes of one parsec or smaller. We forecast that a similar approach based on proper accelerations across the entire sky with data from Gaia DR4 may be sensitive to substructure fractions of fl ≳ 10−3 in the much lower mass range of 10 M⊙ ≲ Ml ≲ 3 × 103 M⊙. We further propose an analogous technique for stacked star-star lensing events in the regime of large impact parameters. Our first implementation is not yet sufficiently sensitive but serves as a useful diagnostic and calibration tool; future data releases should enable average stellar mass measurements using this stacking method.

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A Contact Binary Misclassified as an Ellipsoidal Variable: Complications for Detached Black Hole Searches

O’Doherty,

Bahramian,

Goodwin

et al. 2024

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Identifying sources exhibiting ellipsoidal variability in large photometric surveys is becoming a promising method to search for candidate detached black holes (BHs) in binaries. This technique aims to exploit the orbital-phase-dependent modulation in optical photometry caused by the BH distorting the shape of the luminous star to constrain the mass ratio of the binary. Without understanding if, or how much, contamination is present in the candidate BH samples produced by this new technique it is hard to leverage them for BH discovery. Here, we follow up one of the best candidates identified from Gaia Data Release 3, Gaia DR3 4042390512917208960, with a radial velocity (RV) campaign. Combined photometric and RV modeling, along with spectral disentangling, suggests that the true mass ratio (the mass of the unseen object divided by the mass of the luminous star) is an order of magnitude smaller than that inferred assuming the modulations arise from ellipsoidal variability. We therefore infer that this system is likely a contact binary, or on the boundary of both stars nearly filling their Roche lobes; however, further observations are required to confidently detect the secondary. We find that the well-known problem of discriminating between ellipsoidal and contact binary light curves results in a larger contamination from contact binaries than previously suggested. Until ellipsoidal variables can be reliably distinguished from contact binaries, samples of BH candidates selected based on ellipsoidal variability are likely to be highly contaminated by contact binaries or similar systems.

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Supplement: “An Isolated Mass-gap Black Hole or Neutron Star Detected with Astrometric Microlensing” (2022, ApJL, 933, L23)

Cited by 4 publications

References 83 publications

A Reanalysis of the Isolated Black Hole Candidate OGLE-2011-BLG-0462/MOA-2011-BLG-191

A Reanalysis of the Isolated Black Hole Candidate OGLE-2011-BLG-0462/MOA-2011-BLG-191

Astrometric weak lensing with Gaia DR3 and future catalogues: searches for dark matter substructure

A Contact Binary Misclassified as an Ellipsoidal Variable: Complications for Detached Black Hole Searches

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