Is there a nearby microlensing stellar remnant hiding in Gaia DR3 astrometry?

Maja Jabłońska; Łukasz Wyrzykowski; Krzysztof A. Rybicki; Katarzyna Kruszyńska; Zofia Kaczmarek; Zephyr Penoyre

doi:10.1051/0004-6361/202244656

paper

Is there a nearby microlensing stellar remnant hiding in Gaia DR3 astrometry?

arXiv:2206.11342 · doi:10.1051/0004-6361/202244656

Abstract

Massive galactic lenses with large Einstein Radii should cause a measurable astrometric microlensing effect, i.e. the light centroid shift due to the motion of the two images. Such a shift in the position of a background star due to microlensing was not included in the $G aia$ astrometric model, therefore significant deviation should cause $G aia$ 's astrometric parameters to be determined incorrectly. Here we studied one of the photometric microlensing events reported in the $G aia$ DR3, GaiaDR3-ULENS-001, for which poor goodness of $G aia$ fit and erroneous parallax could indicate the presence of the astrometric microlensing signal. Based on the photometric microlensing model, we simulated $G aia$ astrometric time-series with the astrometric microlensing effect added. We found that including microlensing with the angular Einstein Radius of $θ_{E}$ = $2.6 0_{- 0.24}^{+ 0.21}$ mas ( $2.4 7_{- 0.24}^{+ 0.28}$ mas) assuming positive (negative) impact parameter $u_{0}$ reproduces well the astrometric quantitie reported by $G aia$ . We estimate the mass of the lens to $1.0 0_{- 0.18}^{+ 0.23}$ $M_{⊙}$ ( $0.7 0_{- 0.13}^{+ 0.17}$ $M_{⊙}$ ) and its distance to $0.9 0_{- 0.11}^{+ 0.14}$ kpc ( $0.6 9_{- 0.09}^{+ 0.13}$ kpc), proposing the lens could be a nearby isolated white dwarf.

Is there a nearby microlensing stellar remnant hiding in Gaia DR3 astrometry?

Abstract

References in corpus (11)

Cited by in corpus (10)