Detecting Extrasolar Asteroid Belts Through Their Microlensing Signatures

TL;DR

This paper introduces a method to detect extrasolar asteroid belts by analyzing their unique gravitational microlensing signatures, which produce distinctive features in light curves detectable by future space telescopes.

Contribution

It demonstrates that asteroid belts create pseudo-caustics in microlensing, enabling their detection through characteristic light curve signatures for various configurations.

Findings

Asteroid belts generate pseudo-caustics causing discontinuous magnification jumps.

Microlensing signatures vary with belt parameters and source trajectories.

Future space missions like WFIRST could detect asteroid belts with Earth-like masses.

Abstract

We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures. Asteroid belt + star lens systems create so-called "pseudo-caustics", regions in the source plane where the magnification exhibits a finite but discontinuous jump. These features allow such systems to generate distinctive signatures in the microlensing light curves for a wide range of belt configurations, with source trajectories as far as tenths of the Einstein ring radius from the centre of the lens. Sample light curves for a range of asteroid belt parameters are presented. In the near future, space-based microlensing surveys like WFIRST, which will have the power to detect percent-level changes in microlensing light curves even with sub-minute exposure times, may be able to discover extrasolar asteroid belts with masses of the order of an earth mass.