Reliable Identifications of AGN from the WISE, 2MASS and Rosat all-sky surveys

TL;DR

The paper introduces the S_IX statistic for identifying AGN candidates using all-sky survey data, resulting in a new, mostly unconfirmed AGN sample that enhances existing catalogs and aids in targeted astrophysical studies.

Contribution

A novel S_IX statistic was developed and applied to all-sky survey data, significantly expanding the catalog of bright AGN and enabling targeted follow-up observations.

Findings

The S_IX statistic predicts AGN with ~95% likelihood.

The W2R sample contains nearly 2,000 new bright AGN.

The method identified 10 new AGN in the Kepler field.

Abstract

We have developed the "S_IX" statistic to identify bright, highly-likely Active Galactic Nucleus (AGN) candidates solely on the basis of WISE, 2MASS and Rosat all-sky survey data. This statistic was optimized with data from the preliminary WISE survey and the SDSS, and tested with Lick 3-m Kast spectroscopy. We find that sources with S_IX < 0 have a <~95% likelihood of being an AGN (defined in this paper as a Seyfert 1, quasar or blazar). This statistic was then applied to the full WISE/2MASS/RASS dataset, including the final WISE data release, to yield the "W2R" sample of 4,316 sources with S_IX < 0. Only 2,209 of these sources are currently in the Veron-Cetty and Veron (VCV) catalog of spectroscopically confirmed AGN, indicating that the W2R sample contains nearly 2,000 new, relatively bright (J <~ 16) AGN. We utilize the W2R sample to quantify biases and incompleteness in the VCV catalog. We find it is highly complete for bright (J < 14), northern AGN, but the completeness drops below 50% for fainter, southern samples and for sources near the Galactic plane. This approach also led to the spectroscopic identification of 10 new AGN in the Kepler field, more than doubling the number of AGN being monitored by Kepler. This has identified ~1 bright AGN every 10 square degrees, permitting construction of AGN samples in any sufficiently large region of sky.