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.

26 pages, 9 figures. High resolution figures and data available from http://www.ucolick.org/~mgeha/MACHO Accepted for publication in the Astronomical Journal

References in corpus (3)

• The time delay of the quadruple quasar RX J0911.4+0551
• Blue Variable Stars from the MACHO database I: Photometry and Spectroscopy of the LMC sample
• Probing the HI Kinematics of the LMC: Toward Interpreting QAL Observations of Protogalactic Velocity Fields

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