Discovery of 5000 Active Galactic Nuclei behind the Magellanic Clouds

TL;DR

This study demonstrates that mid-infrared color selection effectively identifies active galactic nuclei behind the Magellanic Clouds, enabling the creation of a large, high-purity AGN catalog for astrophysical research.

Contribution

It shows mid-IR color selection works in dense stellar fields and provides a catalog of ~5000 AGN candidates behind the Magellanic Clouds.

Findings

Mid-IR selection is effective in dense stellar regions.

Created a catalog of approximately 5000 AGN candidates.

Potential to enhance astrometric and absorption line studies.

Abstract

We show that using mid-IR color selection to find active galactic nuclei (AGN) is as effective in dense stellar fields such as the Magellanic Clouds as it is in extragalactic fields with low stellar densities using comparisons between the Spitzer Deep, Wide-Field Survey data for the NOAO Deep Wide Field Survey Bootes region and the SAGE Survey of the Large Magellanic Cloud. We use this to build high purity catalogs of ~ 5000 AGN candidates behind the Magellanic Clouds. Once confirmed, these quasars will expand the available astrometric reference sources for the Clouds and the numbers of quasars with densely sampled, long-term (>decade) monitoring light curves by well over an order of magnitude and potentially identify sufficiently bright quasars for absorption line studies of the interstellar medium of the Clouds.