Sub-Neptunes Show a Stronger Correlation with Cold Jupiters than Super-Earths Especially in Metal-rich Systems

Abstract

Correlations between the inner small planets and cold giants encodes the formation and evolution of planetary systems. It remains unclear if the correlation differs on the two sides of the radius valley. In this work, we compute the conditional frequency of cold Jupiters in systems with only inner sub-Neptunes $P(CJ|SN)$ and those with only inner super-Earths $P(CJ|SE)$. We find that, around transiting sample around metal-rich stars, $P(CJ|SN,[Fe/H]>0)$ and $P(CJ|SE,[Fe/H]>0)$ are $42.6_{-9.9}^{+10.6}\%$ and $14.5_{-6.9}^{+12.7}\%$. Comparing with the field giant frequency ($14.3_{-1.8}^{+2.0}\%$), we show that inner sub-Neptunes and cold Jupiters exhibit a significant positive correlation for metal-rich systems with a confidence level of 99.95\%, whereas this correlation is absent for systems with super-Earths. We also consider a homogeneous Kepler-Keck subsample and derive similar results, with $P(CJ|SN,[Fe/H]>0)$ of $45.8_{-16.3}^{+18.6}\%$ and $P(CJ|SE,[Fe/H]>0)$ of $13.3_{-6.8}^{+17.0}\%$. Radial velocity sample shows consistent results, with metal-rich systems hosting massive inner planets exhibiting a strong positive correlation (confidence level of 99.11\%) with outer cold Jupiters ($P(CJ|{\mathrm{M}}_{\mathrm{p}}>10{\mathrm{M}}_{\oplus },[Fe/H]>0)=34.6_{-9.1}^{+11.0}\%$). These results can be naturally understood since metal-rich disks are expected to more efficiently produce both outer cold Jupiters and inner planets with larger radii and masses. Our findings highlight the critical role of stellar metallicity in shaping planetary architectures, particularly for large/massive planets.

10 pages, 5 figures and 1 table (1 figure and 1 table in Appendix), Published in ApJL

References in corpus (14)

• Growth Model Interpretation of Planet Size Distribution
• The Gaia-Kepler Stellar Properties Catalog. II. Planet Radius Demographics as a Function of Stellar Mass and Age
• Cold Jupiters and improved masses in 38 Kepler and K2 small planet systems from 3661 HARPS-N radial velocities. No excess of cold Jupiters in small planet systems
• A deep radius valley revealed by Kepler short cadence observations
• The Kepler Giant Planet Search. I: A Decade of Kepler Planet-host Radial Velocities from W. M. Keck Observatory
• Giants are bullies: how their growth influences systems of inner sub-Neptunes and super-Earths
• Shallower radius valley around low-mass hosts: Evidence for icy planets, collisions or high-energy radiation scatter
• Planetary Population Synthesis and the Emergence of Four Classes of Planetary System Architectures
• Small Planets Around Cool Dwarfs: Enhanced Formation Efficiency of Super-Earths around M dwarfs
• Planets Across Space and Time (PAST). V. The evolution of hot Jupiters revealed by the age distribution of their host stars
• The intrinsic multiplicity distribution of exoplanets revealed from the radial velocity method
• Planets Across Space and Time (PAST). III. Morphology of the Planetary Radius Valley as a Function of Stellar Age and Metallicity in the Galactic Context Revealed by the LAMOST-Gaia-Kepler Sample
• Cold Jupiters and small planets: Friends, foes, or indifferent? A search for correlations with the largest exoplanet samples
• The New Generation Planetary Population Synthesis (NGPPS) VIII. Impact of host star metallicity on planet occurrence rates, orbital periods, eccentricities, and radius valley morphology