On the radial distribution of giant exoplanets at Solar System scales

TL;DR

This paper reevaluates the radial distribution of giant exoplanets, highlighting uncertainties in current data beyond 5-8 au and questioning the previously suggested decline in their occurrence rate at larger distances.

Contribution

It critically assesses existing radial distribution data of giant exoplanets, emphasizing limitations and uncertainties in the characterization of long-period planets.

Findings

Radial distributions beyond 5-8 au are uncertain.

The decline in giant planet occurrence beyond 1-3 au is not confirmed.

Existing data may not reliably depict the true distribution at large distances.

Abstract

Context. Giant planets play a major role in multiple planetary systems. Knowing their demographics is important to test their overall impact on planetary systems formation. It is also important to test their formation processes. Recently, three radial velocity surveys have established radial distributions of giant planets. All show a steep increase up to 1-3 au, and two suggest a decrease beyond. Aims. We aim at understanding the limitations associated with the characterization of long-period giant radial velocity planets, and to estimate their impact on the radial distribution of these planets. Methods. We revisit the results obtained by two major surveys that derived such radial distributions, using the RV data available at the time of the surveys as well as, whenever possible, new data. Results. We show that the radial distributions published beyond (5-8 au) are not secure. More precisely, the decrease of the radial distribution beyond the peak at 1-3 au is not confirmed.