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Title: Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs

Abstract

No true extrasolar Earth analog is known. Hundreds of planets have been found around Sun-like stars that are either Earth-sized but on shorter periods, or else on year-long orbits but somewhat larger. Under strong assumptions, exoplanet catalogs have been used to make an extrapolated estimate of the rate at which Sun-like stars host Earth analogs. These studies are complicated by the fact that every catalog is censored by non-trivial selection effects and detection efficiencies, and every property (period, radius, etc.) is measured noisily. Here we present a general hierarchical probabilistic framework for making justified inferences about the population of exoplanets, taking into account survey completeness and, for the first time, observational uncertainties. We are able to make fewer assumptions about the distribution than previous studies; we only require that the occurrence rate density be a smooth function of period and radius (employing a Gaussian process). By applying our method to synthetic catalogs, we demonstrate that it produces more accurate estimates of the whole population than standard procedures based on weighting by inverse detection efficiency. We apply the method to an existing catalog of small planet candidates around G dwarf stars. We confirm a previous result that the radius distribution changesmore » slope near Earth's radius. We find that the rate density of Earth analogs is about 0.02 (per star per natural logarithmic bin in period and radius) with large uncertainty. This number is much smaller than previous estimates made with the same data but stronger assumptions.« less

Authors:
;  [1]
  1. Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)
Publication Date:
OSTI Identifier:
22370292
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CATALOGS; DATA ANALYSIS; DENSITY; DETECTION; DISTRIBUTION; EFFICIENCY; ELEMENT ABUNDANCE; GAUSSIAN PROCESSES; ORBITS; PROBABILISTIC ESTIMATION; SUN

Citation Formats

Foreman-Mackey, Daniel, Hogg, David W., and Morton, Timothy D., E-mail: danfm@nyu.edu. Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs. United States: N. p., 2014. Web. doi:10.1088/0004-637X/795/1/64.
Foreman-Mackey, Daniel, Hogg, David W., & Morton, Timothy D., E-mail: danfm@nyu.edu. Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs. United States. https://doi.org/10.1088/0004-637X/795/1/64
Foreman-Mackey, Daniel, Hogg, David W., and Morton, Timothy D., E-mail: danfm@nyu.edu. 2014. "Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs". United States. https://doi.org/10.1088/0004-637X/795/1/64.
@article{osti_22370292,
title = {Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs},
author = {Foreman-Mackey, Daniel and Hogg, David W. and Morton, Timothy D., E-mail: danfm@nyu.edu},
abstractNote = {No true extrasolar Earth analog is known. Hundreds of planets have been found around Sun-like stars that are either Earth-sized but on shorter periods, or else on year-long orbits but somewhat larger. Under strong assumptions, exoplanet catalogs have been used to make an extrapolated estimate of the rate at which Sun-like stars host Earth analogs. These studies are complicated by the fact that every catalog is censored by non-trivial selection effects and detection efficiencies, and every property (period, radius, etc.) is measured noisily. Here we present a general hierarchical probabilistic framework for making justified inferences about the population of exoplanets, taking into account survey completeness and, for the first time, observational uncertainties. We are able to make fewer assumptions about the distribution than previous studies; we only require that the occurrence rate density be a smooth function of period and radius (employing a Gaussian process). By applying our method to synthetic catalogs, we demonstrate that it produces more accurate estimates of the whole population than standard procedures based on weighting by inverse detection efficiency. We apply the method to an existing catalog of small planet candidates around G dwarf stars. We confirm a previous result that the radius distribution changes slope near Earth's radius. We find that the rate density of Earth analogs is about 0.02 (per star per natural logarithmic bin in period and radius) with large uncertainty. This number is much smaller than previous estimates made with the same data but stronger assumptions.},
doi = {10.1088/0004-637X/795/1/64},
url = {https://www.osti.gov/biblio/22370292}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 795,
place = {United States},
year = {Sat Nov 01 00:00:00 EDT 2014},
month = {Sat Nov 01 00:00:00 EDT 2014}
}