Searching for Planet Nine with Coadded WISE and NEOWISE-Reactivation Images

Abstract

A distant, as yet unseen ninth planet has been invoked to explain various observations of the outer solar system. While such a 'Planet Nine', if it exists, is most likely to be discovered via reflected light in the optical, it may emit much more strongly at 3$-$5$\mu$m than simple blackbody predictions would suggest, depending on its atmospheric properties (Fortney et al. 2016). As a result, Planet Nine may be detectable at 3.4$\mu$m with WISE, but single exposures are too shallow except at relatively small distances ($d_9\lesssim 430$ AU). We develop a method to search for Planet Nine far beyond the W1 single-exposure sensitivity, to distances as large as 800 AU, using inertial coadds of W1 exposures binned into $\sim$1 day intervals. We apply our methodology to $\sim$2000 square degrees of sky identified by Holman & Payne (2016) as a potentially likely Planet Nine location, based on the Fienga et al. (2016) Cassini ranging analysis. We do not detect a plausible Planet Nine candidate, but are able to derive a detailed completeness curve, ruling out its presence within the parameter space searched at $W1<16.66$ (90% completeness). Our method uses all publicly available W1 imaging, spanning 2010 January to 2015 December, and will become more sensitive with future NEOWISE-Reactivation releases of additional W1 exposures. We anticipate that our method will be applicable to the entire high Galactic latitude sky, and we will extend our search to that full footprint in the near future.

arXiv commentas submitted to AAS Journals on 4 October 2016

References in corpus (20)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• The SIMBAD astronomical database
• Preliminary Results from NEOWISE: An Enhancement to the Wide-field Infrared Survey Explorer for Solar System Science
• Initial Performance of the NEOWISE Reactivation Mission
• Evidence for a Distant Giant Planet in the Solar System
• unWISE: unblurred coadds of the WISE imaging
• Discovery of a candidate inner Oort cloud planetoid
• Orbit Fitting and Uncertainties for Kuiper Belt Objects
• Automated Transient Identification in the Dark Energy Survey
• Observational constraints on the orbit and location of Planet Nine in the outer solar system
• A Full-sky, High-resolution Atlas of Galactic 12 micron Dust Emission with WISE
• New Extreme Trans-Neptunian Objects: Towards a Super-Earth in the Outer Solar System
• Constraints on the location of a possible 9th planet derived from the Cassini data
• Observational Constraints on Planet Nine: Cassini Range Observations
• The Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and Detectability
• A serendipitous all sky survey for bright objects in the outer solar system
• Evolution and Magnitudes of Candidate Planet Nine
• Cosmologists in Search of Planet Nine: the Case for CMB Experiments
• Finding Planet Nine: apsidal anti-alignment Monte Carlo results

Cited by in corpus (13)

• The Planet Nine Hypothesis
• A new physical interpretation of optical and infrared variability in quasars
• What if Planet 9 is a Primordial Black Hole?
• Deep Full-sky Coadds from Three Years of WISE and NEOWISE Observations
• The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
• Spitzer Follow-up of Extremely Cold Brown Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
• unTimely: a Full-sky, Time-Domain unWISE Catalog
• A 3pi Search for Planet Nine at 3.4 microns with WISE and NEOWISE
• Can the gravitational effect of Planet X be detected in current-era tracking of the known major and minor planets?
• A search for Planet 9 in the IRAS data
• Deep Co-Added Sky from Catalina Sky Survey Images
• What if planet 9 has satellites?
• A Far-Infrared Search for Planet Nine Using AKARI All-Sky Survey