English

Friends not Foes: Strong Correlation between Inner Super-Earths and Outer Gas Giants

Earth and Planetary Astrophysics 2024-05-24 v2

Abstract

The connection between outer gas giants and inner super-Earths reflects their formation and evolutionary histories. Past work exploring this link has suggested a tentative positive correlation between these two populations, but these studies have been limited by small sample sizes and in some cases sample biases. Here we take a new look at this connection with a sample of 184 super-Earth systems with publicly available radial velocity data and resolved outer gas giants. We calculate the frequency of outer gas giants (GG) in super-Earth (SE) systems, dividing our sample into metal-rich ([Fe/H] >> 0) and metal-poor ([Fe/H]\leq0) hosts. We find P(GG|SE, [Fe/H]>>0) = 28.04.6+4.9%^{+4.9}_{-4.6}\% and P(GG|SE, [Fe/H]\leq0) = 4.51.9+2.6%^{+2.6}_{-1.9}\%. Comparing these conditional occurrence rates to field giant occurrence rates from Rosenthal et al 2021, we show that there is a distinct positive correlation between inner super-Earths and outer gas giants for metal-rich host stars at the 2.7σ\sigma level, but this correlation disappears for metal-poor systems. We further find that, around metal-rich stars, the GG/SE correlation enhances slightly for systems with giants that are more distant (beyond 3 AU), more eccentric (e>0.2e > 0.2), and/or in multi-gas giant systems. Such trends disappear around metal-poor stars with the exception of systems of multiple giants in which we observe a tentative anti-correlation. Our findings highlight the critical role metallicity (disk solid budget) plays in shaping the overall planetary architecture.

Keywords

Cite

@article{arxiv.2403.08873,
  title  = {Friends not Foes: Strong Correlation between Inner Super-Earths and Outer Gas Giants},
  author = {Marta L. Bryan and Eve J. Lee},
  journal= {arXiv preprint arXiv:2403.08873},
  year   = {2024}
}

Comments

accepted to ApJL