A Deep Keck/NIRC2 Search for Thermal Emission from Planetary Companions Orbiting Fomalhaut

Abstract

We present deep Keck/NIRC2 1.6 and 3.8 $\mu m$ imaging of Fomalhaut to constrain the near-infrared (IR) brightness of Fomalhaut b, recently confirmed as a likely planet (Currie et al. 2012a), and search for additional planets at r_proj = 15--150 AU. Using advanced/novel PSF subtraction techniques, we identify seven candidate substellar companions at projected separations comparable to Fomalhaut b. However, multi-epoch data shows them to be background objects. We set a new 3-$\sigma$ upper limit for Fomalhaut b's H-band brightness of m(H) $\sim$ 23.15 or 1.5 to 4.5 M_J, depending on the system age and planet cooling models used. We do not recover the possible point source reported from Spitzer/IRAC data: at its location detection limits are similar to those for Fomalhaut b. Our data when combined with other recent work rule out planets with masses and projected separations comparable to HR 8799 bcde and planets with masses M $>$ 3 M_{J} at r_proj $>$ 45 AU. The James Webb Space Telescope will likely be required to shed substantial further light on Fomalhaut's planetary system.

14 pages, 3 figures, 2 tables; minor changes from version 1; Accepted for publication in ApJ Letters

References in corpus (10)

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Cited by in corpus (14)

• Imaging Extrasolar Giant Planets
• Direct Imaging and Spectroscopy of a Candidate Companion Below/Near the Deuterium-Burning Limit In The Young Binary Star System, ROXs 42B
• Deep Thermal Infrared Imaging of HR 8799 bcde: New Atmospheric Constraints and Limits on a Fifth Planet
• Predictions for Shepherding Planets in Scattered Light Images of Debris Disks
• Gap Clearing by Planets in a Collisional Debris Disk
• High-contrast Imaging with Spitzer: Deep Observations of Vega, Fomalhaut, and epsilon Eridani
• On the Morphology and Chemical Composition of the HR 4796A Debris Disk
• Fomalhaut b as a Dust Cloud: Frequent Collisions within the Fomalhaut Disk
• Fomalhaut b as a Cloud of Dust: Testing Aspects of Planet Formation Theory
• Insights on the dynamical history of the Fomalhaut system - Investigating the Fom c hypothesis
• A Bayesian Framework for Exoplanet Direct Detection and Non-Detection
• ALMA imaging of the M-dwarf Fomalhaut C's debris disc
• Collisional Cascade Caclulations for Irregular Satellite Swarms in Fomalhaut b
• ALMA and Keck analysis of Fomalhaut field sources: JWST's Great Dust Cloud is a background object