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arXiv · 2409.13015

First Resolution of Microlensed Images of a Binary-Lens Event

Zexuan Wu·Subo Dong·A. Mérand·Christopher S. Kochanek·Przemek Mróz·Jinyi Shangguan·Grant Christie·Thiam-Guan Tan·Thomas Bensby·Joss Bland-Hawthorn·Sven Buder·Frank Eisenhauer·Andrew P. Gould·Janez Kos·Tim Natusch·Sanjib Sharma·Andrzej Udalski·J. Woillez·David A. H. Buckley·I. B. Thompson·Karim Abd El Dayem·Anthony Berdeu·Jean-Philippe Berger·Guillaume Bourdarot·Wolfgang Brandner·Richard I. Davies·Denis Defrère·Catherine Dougados·Antonia Drescher·Andreas Eckart·Maximilian Fabricius·Helmut Feuchtgruber·Natascha M. Förster Schreiber·Paulo Garcia·Reinhard Genzel·Stefan Gillessen·Gernot Heißel·Sebastian Hönig·Mathis Houlle·Pierre Kervella·Laura Kreidberg·Sylvestre Lacour·Olivier Lai·Romain Laugier·Jean-Baptiste Le Bouquin·James Leftley·Bruno Lopez·Dieter Lutz·Felix Mang·Florentin Millour·Miguel Montargès·Hugo Nowacki·Mathias Nowak·Thomas Ott·Thibaut Paumard·Karine Perraut·Guy Perrin·Romain Petrov·Pierre-Olivier Petrucci·Nicolas Pourre·Sebastian Rabien·Diogo C. Ribeiro·Sylvie Robbe-Dubois·Matteo Sadun Bordoni·Daryl Santos·Jonas Sauter·Jules Scigliuto·Taro T. Shimizu·Christian Straubmeier·Eckhard Sturm·Matthias Subroweit·Calvin Sykes·Linda Tacconi·Frédéric Vincent·Felix Widmann
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Abstract

We resolve the multiple images of the binary-lens microlensing event ASASSN-22av using the GRAVITY instrument of the Very Large Telescope Interferometer (VLTI). The light curves show weak binary-lens perturbations, complicating the analysis, but the joint modeling with the VLTI data breaks several degeneracies, arriving at a strongly favored solution. Thanks to precise measurements of angular Einstein radius \theta_E = 0.724 +/- 0.002 mas and microlens parallax, we determine that the lens system consists of two M dwarfs with masses of M_1 = 0.258 +/- 0.008 M_sun and M_2 = 0.130 +/- 0.007 M_sun, a projected separation of r_\perp = 6.83 +/- 0.31 au and a distance of D_L = 2.29 +/- 0.08 kpc. The successful VLTI observations of ASASSN-22av open up a new path for studying intermediate-separation (i.e., a few astronomical units) stellar-mass binaries, including those containing dark compact objects such as neutron stars and stellar-mass black holes.

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Zexuan Wu, Subo Dong, A. Mérand, Christopher S. Kochanek, Przemek Mróz, Jinyi Shangguan, Grant Christie, Thiam-Guan Tan, Thomas Bensby, Joss Bland-Hawthorn, Sven Buder, Frank Eisenhauer, Andrew P. Gould, Janez Kos, Tim Natusch, Sanjib Sharma, Andrzej Udalski, J. Woillez, David A. H. Buckley, I. B. Thompson, Karim Abd El Dayem, Anthony Berdeu, Jean-Philippe Berger, Guillaume Bourdarot, Wolfgang Brandner, Richard I. Davies, Denis Defrère, Catherine Dougados, Antonia Drescher, Andreas Eckart, Maximilian Fabricius, Helmut Feuchtgruber, Natascha M. Förster Schreiber, Paulo Garcia, Reinhard Genzel, Stefan Gillessen, Gernot Heißel, Sebastian Hönig, Mathis Houlle, Pierre Kervella, Laura Kreidberg, Sylvestre Lacour, Olivier Lai, Romain Laugier, Jean-Baptiste Le Bouquin, James Leftley, Bruno Lopez, Dieter Lutz, Felix Mang, Florentin Millour, Miguel Montargès, Hugo Nowacki, Mathias Nowak, Thomas Ott, Thibaut Paumard, Karine Perraut, Guy Perrin, Romain Petrov, Pierre-Olivier Petrucci, Nicolas Pourre, Sebastian Rabien, Diogo C. Ribeiro, Sylvie Robbe-Dubois, Matteo Sadun Bordoni, Daryl Santos, Jonas Sauter, Jules Scigliuto, Taro T. Shimizu, Christian Straubmeier, Eckhard Sturm, Matthias Subroweit, Calvin Sykes, Linda Tacconi, Frédéric Vincent, Felix Widmann. 2024-09-19. First Resolution of Microlensed Images of a Binary-Lens Event. https://doi.org/10.3847/1538-4357/ad90b9

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