The Magellanic Quasars Survey. I. Doubling the Number of Known AGNs Behind the Small Magellanic Cloud

TL;DR

This study spectroscopically confirmed 29 new quasars behind the Small Magellanic Cloud, significantly increasing known AGNs in the region, and demonstrated their potential for future astrophysical research.

Contribution

It presents the first large-scale spectroscopic confirmation of quasars behind the SMC using mid-IR and optical variability selection methods.

Findings

Confirmed 29 new quasars behind the SMC

Achieved 40% detection efficiency for bright quasars

Identified potential for using AGNs in future astrophysical studies

Abstract

We report the spectroscopic confirmation of 29 new, 12 plausible, and 3 previously known quasars behind the central ~1.5 deg^2 region of the Small Magellanic Cloud. These were identified in a single 2df/AAOmega observation on the Anglo-Australian Telescope of 268 candidates selected primarily based on their mid-IR colors, along with a smaller number of optically variable sources in OGLE-II close to known X-ray sources. The low detection efficiency was partly expected from the high surface density of SMC as compared to the LMC targets and the faintness of many of them (149 with I>20 mag). The expected number of I<20 mag quasars in the field is ~38, and we found 15 (22 with plausible) or 40% (60%). We did not attempt to determine the nature of the remaining sources, although several appear to be new planetary nebulae. The newly discovered AGNs can be used as reference points for future proper motion studies, to study absorption in the interstellar medium, and to study the physics of quasar variability with the existing long-term, highly cadenced OGLE light curves.