Prediction of astrometric microlensing events during theGaiamission

Abstract

We identify stars with large proper motions that are potential candidates for the astrometric microlensing effect during the Gaia mission i.e. between 2012 and 2019. The effect allows a precise measurement of the mass of a single star that is acting as a lens. We construct a candidate list by combining information from several input catalogs including PPMXL, LSPM, PPMX, OGLEBG, and UCAC3. The selection of the microlensing candidates includes the verification of their proper motions as well as the calculation of the centroid shift of the source resulting from the astrometric microlensing effect. The assembled microlensing catalog comprises 1118 candidates for the years 2012 to 2019. Our analysis demonstrates that 96% of the (high) proper motions of these candidates are erroneous. We are thus left with 43 confirmed candidates for astrometric microlensing during the expected Gaia mission. For most of them the light centroid shift is below ∼100 μas (assuming a dark lens) or the astrometric deviation is considerably reduced by the brightness of the lens. Due to this the astrometric microlensing effect can potentially be measured for nine candidates that have a centroid shift between 100 and 4000 μas. For two of these astrometric microlensing candidates we predict a strong centroid shift of about 1000 and 4000 μas, respectively, that should be observable over a period of a few months up to a few years with the Gaia mission.

Weak deflection gravitational lensing for photons coupled to Weyl tensor in a Schwarzschild black hole

“…Plenty of projects [62][63][64][65][66][67] on Galactic microlensing measure change of the total fluxes of stars in the bulge with time, while astrometric microlensing on centroid shifts of a remote source by a nearby lens is also discussed [68][69][70] and practiced [71][72][73].…”

Close stellar conjunctions ofαCentauri A and B until 2050

“…As predicted by Paczynski (1996b) and discussed in details by Di Stefano (2008a,b) the close conjunction of a foreground mass as α Cen with a distant background star will create a gravitational mesolensing event. Lists of stellar conjunctions have been predicted for example, by Salim & Gould (2000), Proft et al (2011), and for specific objects by Lépine & Di Stefano (2012;VB 10) and Sahu et al (2014;Proxima). But to our knowledge, none of the predicted lensing events has been observed successfully due to the very small observational signature of the expected gravitational deflection.…”

Microlensing and Its Degeneracy Breakers: Parallax, Finite Source, High-Resolution Imaging, and Astrometry

“…While resolving the source and lens, as well as measure the astrometric microlensing are feasible with the state-of-the-art instruments, in order to better break the microlensing degeneracy, it is essential to achieve exquisite astrometry. For example, Proft et al [89] predicted 43 astrometric microlensing events will be caused by high proper motion stars between 2012 and 2019. However, the majority of them will have centroid shifts below 0.1 mas, and only nine of them will have measurable centroid shift between 0.1 and 4 mas.…”