Can Gaia find planets around white dwarfs?

TL;DR

This paper predicts Gaia's capability to detect long-period exoplanets around white dwarfs, estimating around 8 such planets, and discusses implications for planetary system evolution and dynamical processes post-main sequence.

Contribution

It provides the first detailed prediction of Gaia's potential to discover planets around white dwarfs, linking detection prospects with planetary evolution theories.

Findings

Gaia will detect approximately 8 planets around white dwarfs.

About 40% of these planets will be less massive than Jupiter.

Most detected planets will be located beyond 3 au from their host stars.

Abstract

The Gaia spacecraft presents an unprecedented opportunity to reveal the population of long period (a>1\,au) exoplanets orbiting stars across the H-R diagram, including white dwarfs. White dwarf planetary systems have played an important role in the study of planetary compositions, from their unique ability to provide bulk elemental abundances of planetary material in their atmospheres. Yet, very little is known about the population of planets around white dwarfs. This paper predicts the population of planets that Gaia will detect around white dwarfs, evolved from known planets orbiting main-sequence stars. We predict that Gaia will detect $8\pm2$ planets around white dwarfs: $8\pm\,3\%$ will lie inside 3\,au and $40\pm10\,\%$ will be less massive than Jupiter. As surviving planets likely become dynamically detached from their outer systems, those white dwarfs with Gaia detected planets may not have planetary material in their atmospheres. Comparison between the predicted planet population and that found by Gaia will reveal the importance of dynamical instabilities and scattering of planets after the main-sequence, as well as whether photoevaporation removes the envelopes of gas giants during their giant branch evolution.