A Word to the WISE: Confusion is Unavoidable for WISE-selected Infrared Excesses

Stars with excess infrared radiation from circumstellar dust are invaluable for studies of exoplanetary systems, informing our understanding of processes of planet formation and destruction alike. All-sky photometric surveys have made the identification of dusty infrared excess candidates trivial, h...

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Bibliographic Details
Published in:The Astrophysical journal 2020-03, Vol.891 (1), p.97
Main Authors: Dennihy, Erik, Farihi, Jay, Fusillo, Nicola Pietro Gentile, Debes, John H.
Format: Article
Language:English
Subjects:
Astrophysics
Circumstellar dust
Confusion
Cosmic dust
Detection limits
Extrasolar planets
Infrared excess
Infrared filters
Infrared imaging
Infrared photometry
Infrared radiation
Infrared stars
Planet formation
Planetary systems
Polls & surveys
Radiation
White dwarf stars
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Summary:Stars with excess infrared radiation from circumstellar dust are invaluable for studies of exoplanetary systems, informing our understanding of processes of planet formation and destruction alike. All-sky photometric surveys have made the identification of dusty infrared excess candidates trivial, however, samples that rely on data from Wise Infrared Survey Explorer (WISE) are plagued with source confusion, leading to high false-positive rates. Techniques to limit its contribution to WISE-selected samples have been developed, and their effectiveness is even more important as we near the end-of-life of Spitzer, the only facility capable of confirming the excess. Here, we present a Spitzer follow-up of a sample of 22 WISE-selected infrared excess candidates near the faint-end of the WISE detection limits. Eight of the 22 excesses are deemed the result of source confusion, with the remaining candidates all confirmed by the Spitzer data. We consider the efficacy of ground-based near-infrared imaging and astrometric filtering of samples to limit confusion among the sample. We find that both techniques are worthwhile for vetting candidates, but fail to identify all of the confused excesses, indicating that they cannot be used to confirm WISE-selected infrared excess candidates, but only to rule them out. This result confirms the expectation that WISE-selected infrared excess samples will always suffer from appreciable levels of contamination, and that care should be taken in their interpretation regardless of the filters applied.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab7249