Reproducing the stellar-mass dependence of the giant planet occurrence rate with pebble accretion models

TL;DR

This study uses pebble-driven core accretion models to reproduce the observed stellar-mass dependence of giant planet occurrence rates, revealing how formation conditions vary with stellar mass.

Contribution

It introduces a population synthesis approach that aligns planet formation models with observed giant planet occurrence trends across different stellar masses.

Findings

Models reproduce the observed peak in giant planet occurrence around 1.7-2 solar masses.

Higher accretion rates and shorter disk lifetimes around massive stars are key factors.

Runaway gas accretion occurs at larger orbital distances and earlier times for more massive stars.

Abstract

The stellar mass dependence of the unbiased giant planet occurrence rate may be the best statistical tool to constrain the formation of such planets. This rate rises and falls as a function of stellar mass, peaking around stars of $\sim 1.7{-}2 \Ms$. In this work, we carry out a population synthesis study, using pebble-driven core accretion model of planet formation, to investigate the planet formation conditions that may be responsible for this stellar-mass dependence. We use the inferred giant planet occurrence rated of three combined homogenised radial velocity surveys (EXPRESS, PPPS, and Lick giant star survey) to constrain the models. We find that we can produce a synthetic giant planet population with closely aligned occurrence and properties when we base our model on observationally-supported assumptions that accretion rates are higher and disk lifetimes are shorter around more massive stars, we can produce a synthetic giant planet population with closely aligned properties to the observed distribution. We also find that in this scenario, the runaway gas accretion occurs at a larger orbital distance and earlier times as the stellar mass increases.