Lens parameters for <i>Gaia</i>18cbf – a long gravitational microlensing event in the Galactic plane

Kruszyńska, K.; Wyrzykowski, Ł.; Rybicki, K.; Maskoliunas, M.; Bachelet, E.; Rattenbury, N. J.; Mróz, P.; Zieliński, Paweł; Hodgkin, S. T.; Ihanec, N.; Gezer, I.; Gromadzki, M.; Mikołajczyk, P.; Stankeviciute, A.; Čepas, V.; Pakštienė, E.; Šiškauskaitė, K.; Zdanavicius, J.; Bozza, V.; Dominik, M.; Jaimes, R. Figuera; Fukui, A.; Hundertmark, M.; Narita, N.; Tsapras, Y.; M., Bronikowski,; Howil, Kornel; Kaczmarek, Zofia; Jabłońska, M.; Jabłonowska, A.; Ziółkowska, O.

doi:10.1051/0004-6361/202142602

Cited by 9 publications

(3 citation statements)

References 82 publications

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“…Similarly, uniform priors for the distances D, proper motions μ, and visual absorption A v,s are used, and a summary can be found in Table 3. This is a similar approach to Mróz & Wyrzykowski (2021) and Kruszyńska et al (2022).…”

Section: Discussionmentioning

confidence: 77%

Estimating Microlensing Parameters from Observables and Stellar Isochrones with pyLIMASS

Bachelet,

Hundertmark,

Calchi Novati

2024

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We present pyLIMASS, a novel algorithm for estimating the physical properties of the lensing system in microlensing events. The main idea of pyLIMASS is to combine all available information regarding the microlensing event, defined as observables, and to estimate the parameter distributions of the system, such as the lens mass and distance. The algorithm is based on isochrones for the stars model and combines the observables using a Gaussian mixture approach. After describing the mathematical formalism and its implementation, we discuss the algorithm’s performance on simulated and published events. Generally, the pyLIMASS estimations are in good agreement (i.e., within 1σ) with the results of the selected published events, making it an effective tool to estimate the lens properties and their distribution. The applicability of the method was tested by using a catalog of realistically simulated events that could be observed by the future Galactic Bulge Time Domain Survey of the Nancy Grace Roman Space Telescope. By solely using constraints from the Roman lightcurves and images, pyLIMASS estimates the masses of the lens of the Roman catalog with a median precision of 20% with almost no bias.

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Section: Discussionmentioning

confidence: 77%

Estimating Microlensing Parameters from Observables and Stellar Isochrones with pyLIMASS

Bachelet,

Hundertmark,

Calchi Novati

2024

Self Cite

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“…The expression for P(t; π E ) depends on the on-sky microlensing event location, and in all work that follows we use the results in Section 3.1 of Golovich et al (2022), which are based on Gould (2013). Annual microlensing parallax can lead to typically subtle (e.g., Alcock et al 1995;Golovich et al 2022;Kaczmarek et al 2022) but sometimes extreme (e.g., Wyrzykowski et al 2016;Kruszyńska et al 2022) asymmetrical deviations from the standard Paczynski (1986) lightcurve.…”

Section: Photometric Microlensingmentioning

confidence: 99%

Disentangling the Black Hole Mass Spectrum with Photometric Microlensing Surveys

Perkins,

McGill,

Dawson

et al. 2024

ApJ

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From the formation mechanisms of stars and compact objects to nuclear physics, modern astronomy frequently leverages surveys to understand populations of objects to answer fundamental questions. The population of dark and isolated compact objects in the Galaxy contains critical information related to many of these topics, but is only practically accessible via gravitational microlensing. However, photometric microlensing observables are degenerate for different types of lenses, and one can seldom classify an event as involving either a compact object or stellar lens on its own. To address this difficulty, we apply a Bayesian framework that treats lens type probabilistically and jointly with a lens population model. This method allows lens population characteristics to be inferred despite intrinsic uncertainty in the lens class of any single event. We investigate this method’s effectiveness on a simulated ground-based photometric survey in the context of characterizing a hypothetical population of primordial black holes (PBHs) with an average mass of 30M ⊙. On simulated data, our method outperforms current black hole (BH) lens identification pipelines and characterizes different subpopulations of lenses while jointly constraining the PBH contribution to dark matter to ≈25%. Key to robust inference, our method can marginalize over population model uncertainty. We find the lower mass cutoff for stellar origin BHs, a key observable in understanding the BH mass gap, particularly difficult to infer in our simulations. This work lays the foundation for cutting-edge PBH abundance constraints to be extracted from current photometric microlensing surveys.

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“…The photometry is publicly available on the GSA web page (Hodgkin et al 2021). We used the procedure described in Kruszyńska et al (2022) to obtain the photometric errors of the 163 measurements used in this study.…”

Section: Gaiamentioning

confidence: 99%

A Close Binary Lens Revealed by the Microlensing Event Gaia20bof

Bachelet,

Rota,

Bozza

et al. 2024

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During the last 25 yr, hundreds of binary stars and planets have been discovered toward the Galactic bulge by microlensing surveys. Thanks to a new generation of large-sky surveys, it is now possible to regularly detect microlensing events across the entire sky. The OMEGA Key Projet at the Las Cumbres Observatory carries out automated follow-up observations of microlensing events alerted by these surveys with the aim of identifying and characterizing exoplanets as well as stellar remnants. In this study, we present the analysis of the binary lens event Gaia20bof. By automatically requesting additional observations, the OMEGA Key Project obtained dense time coverage of an anomaly near the peak of the event, allowing characterization of the lensing system. The observed anomaly in the lightcurve is due to a binary lens. However, several models can explain the observations. Spectroscopic observations indicate that the source is located at ≤2.0 kpc, in agreement with the parallax measurements from Gaia. While the models are currently degenerate, future observations, especially the Gaia astrometric time series as well as high-resolution imaging, will provide extra constraints to distinguish between them.

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Lens parameters for Gaia18cbf – a long gravitational microlensing event in the Galactic plane

Cited by 9 publications

References 82 publications

Estimating Microlensing Parameters from Observables and Stellar Isochrones with pyLIMASS

Estimating Microlensing Parameters from Observables and Stellar Isochrones with pyLIMASS

Disentangling the Black Hole Mass Spectrum with Photometric Microlensing Surveys

A Close Binary Lens Revealed by the Microlensing Event Gaia20bof

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