First Resolution of Microlensed Images of a Binary-Lens Event
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.
Keywords
Cite
@article{arxiv.2409.13015,
title = {First Resolution of Microlensed Images of a Binary-Lens Event},
author = {Zexuan Wu and Subo Dong and A. Mérand and Christopher S. Kochanek and Przemek Mróz and Jinyi Shangguan and Grant Christie and Thiam-Guan Tan and Thomas Bensby and Joss Bland-Hawthorn and Sven Buder and Frank Eisenhauer and Andrew P. Gould and Janez Kos and Tim Natusch and Sanjib Sharma and Andrzej Udalski and J. Woillez and David A. H. Buckley and I. B. Thompson and Karim Abd El Dayem and Anthony Berdeu and Jean-Philippe Berger and Guillaume Bourdarot and Wolfgang Brandner and Richard I. Davies and Denis Defrère and Catherine Dougados and Antonia Drescher and Andreas Eckart and Maximilian Fabricius and Helmut Feuchtgruber and Natascha M. Förster Schreiber and Paulo Garcia and Reinhard Genzel and Stefan Gillessen and Gernot Heißel and Sebastian Hönig and Mathis Houlle and Pierre Kervella and Laura Kreidberg and Sylvestre Lacour and Olivier Lai and Romain Laugier and Jean-Baptiste Le Bouquin and James Leftley and Bruno Lopez and Dieter Lutz and Felix Mang and Florentin Millour and Miguel Montargès and Hugo Nowacki and Mathias Nowak and Thomas Ott and Thibaut Paumard and Karine Perraut and Guy Perrin and Romain Petrov and Pierre-Olivier Petrucci and Nicolas Pourre and Sebastian Rabien and Diogo C. Ribeiro and Sylvie Robbe-Dubois and Matteo Sadun Bordoni and Daryl Santos and Jonas Sauter and Jules Scigliuto and Taro T. Shimizu and Christian Straubmeier and Eckhard Sturm and Matthias Subroweit and Calvin Sykes and Linda Tacconi and Frédéric Vincent and Felix Widmann},
journal= {arXiv preprint arXiv:2409.13015},
year = {2024}
}
Comments
Published in ApJ. See the ancillary file for animation associated with Fig. 8