back OGLE Homepage

Observations of microlensed images with dual-field interferometry: on-sky demonstration and prospects

P. Mróz, S. Dong, A. Mérand, J. Shangguan, J. Woillez, A. Gould, A. Udalski, F. Eisenhauer, Y.-H. Ryu, Z. We, Z. Loi, H. Yang, G. Bourdarot, D. Defrère, A. Drescher, M. Fabricius, P. Garcia, R. Genzel, S. Gillessen, S. F. Hönig, L. Kreidberg, J.-B. Le Bouquin, D. Lutz, F. Millour, T. Ott, T. Paumard, J. Sauter, T. T. Shimizu, C. Staubmeier, M. Subroweit, F. Widmann, M. K. Szymański, I. Soszyński, P. Pietrukowicz, S. Kozłowski, R. Poleski, J. Skowron, K. Ulaczyk, M. Gromadzki, K. Rybicki, P. Iwanek, M. Wrona, M. Mróz, M. D. Albrow, S.-J. Chung, C. Han, K.-H. Hwang, Y. K. Jung, I.-G. Shin, Y. Shvartzvald, J. C. Yee, W. Zang, S.-M. Cha, D.-J. Kim, S.-L. Kim, C.-U. Lee, D.-J. Lee, Y. Lee, B.-G. Park, and R. W. Pogge
arXiv:2409.12227

Interferometric observations of gravitational microlensing events offer an opportunity for precise, efficient, and direct mass and distance measurements of lensing objects, especially those of isolated neutron stars and black holes. However, such observations were previously possible for only a handful of extremely bright events. The recent development of a dual-field interferometer, GRAVITY Wide, has made it possible to reach out to significantly fainter objects, and increase the pool of microlensing events amenable to interferometric observations by two orders of magnitude. Here, we present the first successful observation of a microlensing event with GRAVITY Wide and the resolution of microlensed images in the event OGLE-2023-BLG-0061/KMT-2023-BLG-0496. We measure the angular Einstein radius of the lens with a sub-percent precision, θE = 1.280 ± 0.009 mas. Combined with the microlensing parallax detected from the event light curve, the mass and distance to the lens are found to be 0.472 ± 0.012 M⊙ and 1.81 ± 0.05 kpc, respectively. We present the procedure for the selection of targets for interferometric observations, and discuss possible systematic effects affecting GRAVITY Wide data. This detection demonstrates the capabilities of the new instrument and it opens up completely new possibilities for the follow-up of microlensing events, and future routine discoveries of isolated neutron stars and black holes.

Light curve of OGLE-2023-BLG-0061/KMT-2023-BLG-0496. Arrows mark the two epochs of VLTI observations.
Light curve of OGLE-2023-BLG-0061/KMT-2023-BLG-0496. Arrows mark the two epochs of VLTI observations.

Reconstructed geometry of the event
Reconstructed geometry of the event. The gray solid line marks the trajectory of the source in the sky. Open symbols (red square and blue circle) mark the position of the source during the two epochs of VLTI observations, whereas the filled symbols mark the positions of the images of the source. The dashed circle shows the Einstein radius.

PLEASE cite the following paper when using the data or referring to these results:
Mróz et al., 2024, arXiv:2409.12227

Any comments about the data and the form of their presentation are welcome as they can improve the future releases of OGLE analysis. Send your messages to this address.

back