Gaia Data Release 3

Abstract

Context. One of the rarest types of variability is the phenomenon of gravitational microlensing, a transient brightening of a background star due to an intervening lensing object. Microlensing is a powerful tool for studying the invisible or otherwise undetectable populations in the Milky Way, including planets and black holes. Aims. We describe the first Gaia catalogue of candidate microlensing events, give an overview of its content, and discuss its validation. Methods. The catalogue of Gaia microlensing events was composed by analysing the light curves of around 2 billion sources of Gaia DR3 from all over the sky covering 34 months, between 2014 and 2017. Results. We present 363 Gaia microlensing events and discuss their properties. Of these, 90 have never been reported before and have not been discovered by other surveys. The contamination of the catalogue is assessed to 0.6%-1.7%.

Prediction of Astrometric and Timing Microlensing Events with Pulsars by ATNF Catalog and Gaia DR3

“…It is the only event in our predictions that has its minimal angular separation comparable to its Einstein ring radius, β 0 ≈ 2θ E , which gives the magnification about 0.07-0.7 mag of this event at t 0 = J2016.0 and might trigger a photometric microlensing event. However, the 363 photometric microlensing candidates published in Gaia DR3 (Gaia Collaboration et al 2023;Wyrzykowski et al 2023) do not include this event, implying that its brightness variation might not pass the sample cuts and selections process. An adequate explanation would demand the intermediate data, which is not publicly available for now.…”

Estimating Microlensing Parameters from Observables and Stellar Isochrones with pyLIMASS

“…In this section, we apply pyLIMASS on observed events published in the literature. Because all of these events, with the exception of Gaia16aye (Wyrzykowski et al 2023), are located toward the Galactic Bulge, we can only make a conservative assumption about the upper limit of the source distance D S < 15 kpc (Penny et al 2019). A summary of the results can be found in the Table 2, but every event is discussed in more detail thereafter.…”

“…Originally, the technique was used to study lens populations of the the Milky Way halo by surveying the source located in the Magellanic Clouds (Paczynski 1986;Alcock et al 2000;Tisserand et al 2007;Wyrzykowski et al 2011). More recently, microlensing surveys have been focused toward the Galactic Bulge (Bond et al 2001;Udalski 2003;Kim et al 2016), where the event rate is highest (Sumi et al 2013;Mróz et al 2019), but microlensing events have also been detected in the entire Galactic Disk (Fukui et al 2019;Wyrzykowski et al 2023). Based on these observations, more than 200 planets have been detected, 3 as well as brown dwarfs (Zhu et al 2016;Chung et al 2017;Bachelet et al 2019;Shvartzvald et al 2019), freefloating planets (Mróz et al 2017(Mróz et al , 2018Sumi et al 2023), stellar binaries (see, e.g., Street et al 2019;Tsapras et al 2019), and stellar remnants (Blackman et al 2021;Sahu et al 2022).…”

The Large Array Survey Telescope—Science Goals

“…Moreover, even the baseline coverage might be useful, e.g., to assess the potential variability of the source, or identify a transient as a genuine microlensing event. It might also be interesting to check for lenses toward potential over-densities (and thus regions with higher microlensing rates), for example the Gould Belt, as suggested by Wyrzykowski et al (2023). We take the opportunity to emphasize again that one of the key challenges is to obtain the manpower and funds, and implement the tools required for using LAST as a microlensing experiment, as well as for other science cases discussed throughput this publication (e.g., ATLAS forced photometry server; Shingles et al 2021), which we further discuss in Ofek et al (2023) (see also https:// github.com/EranOfek/AstroPack).…”