Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields
Abstract
We present 47 spectroscopically-confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the Small Magellanic Cloud, more than tripling the number of quasars previously known in this region. The quasars cover the redshift interval 0.2 < z < 2.8 and apparent mean magnitudes 16.6 < V < 20.1. We discuss the details of quasar candidate selection based on time variability in the MACHO database and present results of spectroscopic follow-up observations. Our follow-up detection efficiency was 20%; the primary contaminants were emission-line Be stars in Magellanic Clouds. For the 47 quasars discovered behind the Magellanic Clouds plus an additional 12 objects previously identified in this region, we present 7.5-year MACHO V- and R-band lightcurves with average sampling times of 2-10 days.
Keywords
Cite
@article{arxiv.astro-ph/0209513,
title = {Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields},
author = {M. Geha and C. Alcock and R. A. Allsman and D. R. Alves and T. S. Axelrod and A. C. Becker and D. P. Bennett and K. H. Cook and A. J. Drake and K. C. Freeman and K. Griest and S. C. Keller and M. J. Lehner and S. L. Marshall and D. Minniti and C. A. Nelson and B. A. Peterson and P. Popowski and M. R. Pratt and P. J. Quinn and C. W. Stubbs and W. Sutherland and A. B. Tomaney and T. Vandehei and D. L. Welch},
journal= {arXiv preprint arXiv:astro-ph/0209513},
year = {2009}
}
Comments
26 pages, 9 figures. High resolution figures and data available from http://www.ucolick.org/~mgeha/MACHO Accepted for publication in the Astronomical Journal