High Contrast Imaging with Spitzer : Constraining the Frequency of Giant Planets out to 1000 AU separations

Stephen Durkan, Markus Janson, Joseph Carson
(Submitted on 4 Apr 2016)

We report results of a re-analysis of archival Spitzer IRAC direct imaging surveys encompassing a variety of nearby stars. Our sample is generated from the combined observations of 73 young stars (median age, distance, spectral type = 85 Myr, 23.3 pc, G5) and 48 known exoplanet host stars with unconstrained ages (median distance, spectral type = 22.6 pc, G5). While the small size of Spitzer provides a lower resolution than 8m-class AO-assisted ground based telescopes, which have been used for constraining the frequency of 0.5 – 13 MJ planets at separations of 10−102 AU, its exquisite infrared sensitivity provides the ability to place unmatched constraints on the planetary populations at wider separations. Here we apply sophisticated high-contrast techniques to our sample in order to remove the stellar PSF and open up sensitivity to planetary mass companions down to 5\arcsec\ separations. This enables sensitivity to 0.5 – 13 MJ planets at physical separations on the order of 102−103 AU , allowing us to probe a parameter space which has not previously been systematically explored to any similar degree of sensitivity. Based on a colour and proper motion analysis we do not record any planetary detections. Exploiting this enhanced survey sensitivity, employing Monte Carlo simulations with a Bayesian approach, and assuming a mass distribution of dn/dm∝m−1.31, we constrain (at 95% confidence) a population of 0.5 – 13 MJ planets at separations of 100 – 1000 AU with an upper frequency limit of 9%.

Comments: 21 pages, 9 figures, 3 tables, accepted for publication in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1604.00859 [astro-ph.EP] (or arXiv:1604.00859v1 [astro-ph.EP] for this version)
Submission history
From: Stephen Durkan
[v1] Mon, 4 Apr 2016 13:53:03 GMT (5514kb)
http://arxiv.org/abs/1604.00859