Letter to the Editor

M-dwarf exoplanet surface density distribution

A log-normal fit from 0.07 to 400 AU

¹ Institute for Astronomy, ETH Zurich Wolfgang-Pauli-Strasse 27, Zurich 8093, Switzerland
² Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA
³ Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, 19 allée du Six Août, 4000 Liège, Belgium

Received: 5 June 2017
Accepted: 14 July 2017

Abstract

Aims. We fit a log-normal function to the M-dwarf orbital surface density distribution of gas giant planets, over the mass range 1–10 times that of Jupiter, from 0.07 to 400 AU.

Methods. We used a Markov chain Monte Carlo approach to explore the likelihoods of various parameter values consistent with point estimates of the data given our assumed functional form.

Results. This fit is consistent with radial velocity, microlensing, and direct-imaging observations, is well-motivated from theoretical and phenomenological points of view, and predicts results of future surveys. We present probability distributions for each parameter and a maximum likelihood estimate solution.

Conclusions. We suggest that this function makes more physical sense than other widely used functions, and we explore the implications of our results on the design of future exoplanet surveys.