Speaker
Description
Microlensing provides a unique way to detect and constrain the masses of isolated, non-luminous objects, including dark stellar remnants. Under favorable conditions, lens masses can be measured using photometric data alone, typically through the detection of finite-source (FS) effects in highly magnified events.
I will present unusual microlensing events identified in Gaia Alerts and Gaia Data Release 3. Despite their high magnifications, these events do not exhibit discernible FS signatures, which can indicate large Einstein radii and, consequently, massive lenses. While direct mass measurements are not possible in these cases, I derive lower limits on the lens masses and use them to constrain the nature of the lensing objects.
The inferred mass limits, reaching ~0.3-0.7 M$_{\odot}$, combined with a high probability of the lenses being non-luminous, identify them as strong candidates for compact remnants such as white dwarfs or neutron stars. As full Gaia astrometric data become available, further study of these events may confirm the inferred masses and the nature of these objects.