Exo-zodi modelling for the Large Binocular Telescope Interferometer

TL;DR

This paper develops a modelling framework to interpret LBTI observations of exo-zodiacal dust, enabling estimation of dust levels and brightness around nearby stars to aid future space missions.

Contribution

It introduces a new model for interpreting LBTI data, linking thermal emission detections to scattered light predictions for habitable zone dust.

Findings

LBTI can detect exo-zodi levels a few times above Solar System levels around Sun-like stars.

The model predicts lower dust levels for more massive stars.

Sensitivity to faint dust levels improves with assumed measurement precision.

Abstract

Habitable zone dust levels are a key unknown that must be understood to ensure the success of future space missions to image Earth analogues around nearby stars. Current detection limits are several orders of magnitude above the level of the Solar System's Zodiacal cloud, so characterisation of the brightness distribution of exo-zodi down to much fainter levels is needed. To this end, the large Binocular Telescope Interferometer (LBTI) will detect thermal emission from habitable zone exo-zodi a few times brighter than Solar System levels. Here we present a modelling framework for interpreting LBTI observations, which yields dust levels from detections and upper limits that are then converted into predictions and upper limits for the scattered light surface brightness. We apply this model to the HOSTS survey sample of nearby stars; assuming a null depth uncertainty of 10$^{-4}$ the LBTI will be sensitive to dust a few times above the Solar System level around Sun-like stars, and to even lower dust levels for more massive stars.