Constraining lens masses in moderately to highly magnified microlensing events from Gaia

Context. Microlensing events provide a unique way to detect and measure the masses of isolated, non-luminous objects, particularly dark stellar remnants. Under certain conditions, it is possible to measure the mass of these objects using photometry alone, specifically when a microlensing light curve displays a finite source (FS) effect. This effect generally occurs in highly magnified light curves, i.e. when the source and the lens are very well aligned. Aims. In this study, we analyse Gaia Alerts and Gaia Data Release 3 datasets, identifying four moderate-to-high-magnification microlensing events without a discernible FS effect. The absence of this effect suggests a large Einstein radius, implying substantial lens masses. Methods. In each event, we constrained the FS effect, and therefore established lower limits for the angular Einstein radius and lens mass. Additionally, we used the DarkLensCode software to obtain the mass, distance, and brightness distribution for the lens based on the Galactic model. Results. Our analysis established lower mass limits of ∼0.7 M ⊙ for one lens and ∼0.3 − 0.5 M ⊙ for two others. A DarkLensCode analysis supports these findings, estimating lens masses in the range of ∼0.42 − 1.70 M ⊙ and dark lens probabilities exceeding 80%. These results strongly indicate that the lenses are stellar remnants, such as white dwarfs or neutron stars. Conclusions. While further investigations are required to confirm the nature of these lenses, we demonstrate a straightforward yet effective approach to identifying stellar remnant candidates.

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Journal
Astronomy and Astrophysics
Published
2025-10-16
DOI
https://doi.org/10.1051/0004-6361/202554935
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
0.00

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article

Constraining lens masses in moderately to highly magnified microlensing events from Gaia

C. Galdies, D. Reichart, K. Howil, M. Ratajczak et al.
Astronomy and Astrophysics
Stellar, planetary, and galactic studies
article

Constraining lens masses in moderately to highly magnified microlensing events from Gaia

C. Galdies, D. Reichart, K. Howil, M. Ratajczak, Ł. Wyrzykowski, O. Kvaratskhelia, V. Godunova, M. Hundertmark, P. Rota, M. Jelínek, A. Simon, M. Stojanović, M. Sitek, Hasan Esenoğlu, M. Żejmo, J. Wambsganß, Adam Popowicz, A. Gurgul, Sebastian Kurowski, O. Tasuya, P. Zielinski, Krzysztof Kotysz, M. Jabłońska, A. Garofalo, Э. Сонбас, A. Cassan, Uliana Pylypenko, R. Figuera Jaimes, J. K. T. Qvam, J. M. Carrasco, T. Kvernadze, M. D. Jovanović, Supachai Awiphan, A. Fukui, S. Zola, K. Kruszyńska, R. A. Street, K. Bąkowska, Jean‐Pierre Rivet, V. Bozza, K. A. Rybicki, Y. Tsapras, J. Zdanavičius, E. Pakštienė, A. Udalski, Tolga Güver, James W. Davidson, M. Dominik, E. Bachelet, N. Ihanec, Stephen M. Brincat, P. Mikołajczyk, U. Burgaz, B. Joachimczyk, Mauritz M. Wicker, G. Damljanović, Z. Kaczmarek, Piotr Hofbauer
article en

Abstract

Context. Microlensing events provide a unique way to detect and measure the masses of isolated, non-luminous objects, particularly dark stellar remnants. Under certain conditions, it is possible to measure the mass of these objects using photometry alone, specifically when a microlensing light curve displays a finite source (FS) effect. This effect generally occurs in highly magnified light curves, i.e. when the source and the lens are very well aligned. Aims. In this study, we analyse Gaia Alerts and Gaia Data Release 3 datasets, identifying four moderate-to-high-magnification microlensing events without a discernible FS effect. The absence of this effect suggests a large Einstein radius, implying substantial lens masses. Methods. In each event, we constrained the FS effect, and therefore established lower limits for the angular Einstein radius and lens mass. Additionally, we used the DarkLensCode software to obtain the mass, distance, and brightness distribution for the lens based on the Galactic model. Results. Our analysis established lower mass limits of ∼0.7 M ⊙ for one lens and ∼0.3 − 0.5 M ⊙ for two others. A DarkLensCode analysis supports these findings, estimating lens masses in the range of ∼0.42 − 1.70 M ⊙ and dark lens probabilities exceeding 80%. These results strongly indicate that the lenses are stellar remnants, such as white dwarfs or neutron stars. Conclusions. While further investigations are required to confirm the nature of these lenses, we demonstrate a straightforward yet effective approach to identifying stellar remnant candidates.

Astronomy and AstrophysicsVol. 705
University of North Carolina at Chapel Hill (US), Silesian University of Technology (PL), Jagiellonian University (PL), Las Cumbres Observatory Global Telescope Network (US), Centre National de la Recherche Scientifique (FR), University of Salerno (IT), Pontificia Universidad Católica de Chile (CL), Vilnius University (LT), Taras Shevchenko National University of Kyiv (UA), George Washington University (US), University of Malta (MT), Trinity College (CA), Trinity College Dublin (IE), University of Wrocław (PL), Heidelberg University (DE), Leibniz Institute for Astrophysics Potsdam (DE), Czech Academy of Sciences, Astronomical Institute (CZ), Institut d'Astrophysique de Paris (FR), Evgeni Kharadze Georgian National Astrophysical Observatory (GE), Nicolaus Copernicus University (PL), Mount Stromlo Observatory (AU), Sorbonne Université (FR), Institut d'Estudis Espacials de Catalunya (ES), Millennium Institute of Astrophysics (CL), National Centre for Nuclear Research (PL), Emergency University (US), Institut Català de Ciències del Clima (ES), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (IT), Flow Pharma (United States) (US), Scottish Universities Physics Alliance (GB), Institute of Theoretical Physics (CN), Observatoire de la Côte d’Azur (FR), Valdres Folkemuseum (NO), Main Astronomical Observatory (UA), Astronomical Institute of the Slovak Academy of Sciences (SK), Nicolaus Copernicus Astronomical Center (PL), Astronomical Observatory (RS), University of Zielona Góra (PL), University of Warsaw (PL), University of Virginia (US), Istanbul Commerce University (TR), Weizmann Institute of Science (IL), Istanbul University (TR), Universitat de Barcelona (ES), The University of Tokyo (JP), National Astronomical Research Institute of Thailand (TH), National Institute for Astrophysics (IT), IAC (United States) (US)
National Science Foundation, Smithsonian Institution, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, California Institute of Technology, Northwestern University, Johns Hopkins University, Drexel University, Space Telescope Science Institute, National Astronomical Research Institute of Thailand, University of Warwick, European Commission, Queen's University Belfast, Durham University, Deutsche Forschungsgemeinschaft, Generalitat de Catalunya, Queen's University, Nuclear Safety and Security Commission, Lietuvos Mokslo Taryba, Ministerstwo Edukacji i Nauki, National Central University, Universitat de Barcelona, Uniwersytet Mikolaja Kopernika w Toruniu, Adiyaman Üniversitesi, Stockholms Universitet, Eötvös Loránd Tudományegyetem, Science Fund of the Republic of Serbia, Thailand Science Research and Innovation, Serbian Academy of Sciences and Arts, Agencia Nacional de Investigación y Desarrollo, Max-Planck-Institut für Astronomie, Goddard Space Flight Center, Smithsonian Astrophysical Observatory, Science Mission Directorate, HORIZON EUROPE Framework Programme, Science and Technology Facilities Council, Agència de Gestió d'Ajuts Universitaris i de Recerca, European Regional Development Fund, Agencia Estatal de Investigación, Institut de Ciències del Cosmos, Integrated Electronics Engineering Center, Binghamton University, Planetary Science Division, Los Alamos National Laboratory, FP7 Research Potential of Convergence Regions
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