# Astrometric microlensing

## TL;DR

Astrometric microlensing enables new insights into lenses and sources by measuring tiny shifts in star positions during gravitational lensing events, especially with Gaia's advanced astrometric capabilities.

## Contribution

This paper analyzes various classes of astrometric microlensing events, including effects like finite source size, blending, and orbital motion, in the context of Gaia observations.

## Key findings

- Astrometric shifts range from micro-arcseconds to milli-arcseconds.
- Different lens-source configurations produce distinct astrometric signatures.
- Gaia's high-precision measurements will significantly enhance microlensing studies.

## Abstract

Astrometric microlensing will offer in the next future a new channel for investigating the nature of both lenses and sources involved in a gravitational microlensing event. The effect, corresponding to the shift of the position of the multiple image centroid with respect to the source star location, is expected to occurr on scales from micro-arcoseconds to milli-arcoseconds depending on the characteristics of the lens-source system. Here, we consider different classes of events (single/binary lens acting on a single/binary source) also accounting for additional effects including the finite source size, the blending and orbital motion. This is particularly important in the era of Gaia observations which is making possible astrometric measurements with unprecedent quality.