The Lyot Project Direct Imaging Survey of Substellar Companions: Statistical Analysis and Information from Nondetections

TL;DR

This study used high-contrast imaging to survey 86 stars for substellar companions, finding no detections but providing statistical constraints on the rarity of giant exoplanets and brown dwarfs around nearby stars.

Contribution

It presents a novel statistical analysis of nondetections using Bayesian methods to constrain substellar companion populations.

Findings

No substellar companions detected in the survey.

Constraints on the frequency of massive substellar companions (<20%).

Confirms the rarity of brown dwarfs around solar-like stars.

Abstract

The Lyot project used an optimized Lyot coronagraph with Extreme Adaptive Optics at the 3.63m Advanced Electro-Optical System telescope (AEOS) to observe 86 stars from 2004 to 2007. In this paper we give an overview of the survey results and a statistical analysis of the observed nondetections around 58 of our targets to place constraints on the population of substellar companions to nearby stars. The observations did not detect any companion in the substellar regime. Since null results can be as important as detections, we analyzed each observation to determine the characteristics of the companions that can be ruled out. For this purpose we use a Monte Carlo approach to produce artificial companions, and determine their detectability by comparison with the sensitivity curve for each star. All the non-detection results are combined using a Bayesian approach and we provide upper limits on the population of giant exoplanets and brown dwarfs for this sample of stars. Our nondetections confirm the rarity of brown dwarfs around solar-like stars and we constrain the frequency of massive substellar companions (M>40Mjup) at orbital separation between and 10 and 50 AU to be <20%.