Detecting circumstellar disks around gravitational microlenses

TL;DR

This paper explores the potential of gravitational microlensing to detect circumstellar disks around stars, analyzing how disks affect light curves and estimating detection rates for debris disks beyond 1 kpc.

Contribution

It introduces a method to account for occultation and gravitational effects of disks in microlensing light curves, providing estimates of detection frequencies.

Findings

Microlensing can detect debris disks beyond 1 kpc.

Approximately 1 debris disk per year could be detected around certain star types.

Existing datasets may already contain signatures of about 10 debris disks.

Abstract

We investigate the chance of detecting proto-planetary or debris disks in stars that induce microlensing events (lenses). The modification of the light curves shapes due to occultation and extinction by the disks as well as the additional gravitational deflection caused by the additional mass is considered. The magnification of gravitational microlensing events is calculated using the ray shooting method. The occultation is taken into account by neglecting or weighting the images on the lens plane according to a transmission map of the corresponding disk for a point source point lens (PSPL) model. The estimated frequency of events is obtained by taking the possible inclinations and optical depths of the disk into account. We conclude that gravitational microlensing can be used, in principle, as a tool for detecting debris disks beyond 1 kpc, but estimate that each year of the order of 1 debris disk is expected for lens stars of F, G, or K spectral type and of the order of 10 debris disks might have shown signatures in existing datasets.