Combining Transit and Radial Velocity: A Synthesized Population Model
Abstract
We present a framework for estimating exoplanet occurrence rates by synthesizing constraints from radial velocity and transit surveys simultaneously. We employ approximate Bayesian computation and various massradius (MR) relations to explore the population models describing these surveys, both separately and in a joint fit. Using this approach, we fit a planet distribution function of the form ${d}^{2}N/d\mathrm{log}{Pd}\mathrm{log}M\propto {P}^{\beta }{M}^{\alpha }$ , with a break in the power law in mass at M_{b}, to planets orbiting FGK stars with periods $P=[25,200]$ days and masses $M=[2,50]{M}_{\oplus }$ . We find that the MR relation from Otegi et al. (2020), which lets rocky and volatilerich populations overlap in mass, allows us to find a model that is consistent with both types of surveys. Our joint fit gives ${M}_{b}={21.6}_{3.2}^{+2.5}{M}_{\oplus }$ (errors reflect 68.3% credible interval). This is nearly a factor of three higher than the break from transitonly considerations and an MR relation without such an overlap. The corresponding planetstar mass ratio break ${q}_{b}\sim 7\times {10}^{5}$ may be consistent with microlensing studies ( ${q}_{b}\sim 6\times {10}^{5}2\times {10}^{4}$ ). The joint fit also requires that a fraction of ${F}_{\mathrm{rocky}}={0.63}_{0.04}^{+0.04}$ planets in the overlap region belong to the rocky population. Our results strongly suggest that future MR relations should account for a mixture of distinct types of planets in order to describe the observed planet population.
 Publication:

The Astronomical Journal
 Pub Date:
 February 2021
 DOI:
 10.3847/15383881/abd2c1
 arXiv:
 arXiv:2012.05423
 Bibcode:
 2021AJ....161...69K
 Keywords:

 Exoplanet astronomy;
 Exoplanet catalogs;
 Exoplanet detection methods;
 Exoplanets;
 Radial velocity;
 Transit photometry;
 Bayesian statistics;
 486;
 488;
 489;
 498;
 1332;
 1709;
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 Astrophysics  Earth and Planetary Astrophysics;
 Astrophysics  Instrumentation and Methods for Astrophysics
 EPrint:
 Accepted for publication in The Astronomical Journal