The search for IR excess in low signal to noise sources

TL;DR

This study develops a weighted detection method using a gamma distribution to identify IR excess sources in low signal-to-noise data, leading to the discovery of new disk candidates and potential exoplanet hosts.

Contribution

Introduces a gamma PDF-based methodology to accurately detect IR excess in faint sources, reducing false positives and uncovering new candidates.

Findings

Re-discovered 25 IR excess sources

Presented 14 new IR excess candidates

Identified a potential directly imageable planet-hosting disk

Abstract

We present sources selected from their Wide-field Infrared Survey Explorer (WISE) colors that merit future observations to image for disks and possible exoplanet companions. Introducing a weighted detection method, we eliminated the enormous number of specious excess seen in low signal to noise objects by requiring greater excess for fainter stars. This is achieved by sorting through the 747 million sources of the ALLWISE database. In examining these dim stars, it can be shown that a non-Gaussian distribution best describes the spread around the main-sequence polynomial fit function. Using a gamma Probability Density Function (PDF), we can best mimic the main sequence distribution and exclude natural fluctuations in IR excess. With this new methodology we re-discover 25 IR excesses and present 14 new candidates. One source (J053010.20-010140.9), suggests a 8.40 $\pm$ 0.73 AU disk, a likely candidate for possible direct imagining of planets that are likely fully formed. Although all of these sources are well within the current flux ratio limit of $\sim$10$^{-6}$ (Wyatt 2008), J223423.85+403515.8 shows the highest bolometric flux ratio ($f_d$=0.0694) between disk and host star, providing a very good candidate for direct imaging of the circumstellar disk itself. In re-examining the Kepler candidate catalog (original study preformed by Kennedy and Wyatt 2012), we found one new candidate that indicates disk like characteristics (TYC 3143-322-1).