Year: 2015
Type: article
Abstract: We present the characterization and initial results from the QUEST–La Silla active galactic nucleus (AGN) variability survey. This is an effort to obtain well-sampled optical light curves in extragalactic fields with unique multiwavelength observations. We present photometry obtained from 2010 to 2012 in the XMM-COSMOS field, which was observed over 150 nights using the QUEST camera on the European Southern Observatory (ESO) Schmidt telescope. The survey uses a broadband filter, the Q band, similar to the union of the g and the r filters, achieving an intrinsic photometric dispersion of 0.05 mag and a systematic error of 0.05 mag in the zero point. Since some detectors of the camera show significant nonlinearity, we use a linear correlation to fit the zero points as a function of the instrumental magnitudes, thus obtaining a good correction to the nonlinear behavior of these detectors. We obtain good photometry to an equivalent limiting magnitude of . The astrometry has an internal precision of and an overall accuracy of when compared to the Sloan Digital Sky Survey. Studying the optical variability of X-ray-detected sources in the XMM-COSMOS field, we find that the survey is ∼75%–80% complete to magnitudes , and ∼67% complete to a magnitude . Additionally, broad-line (BL) AGNs have larger variation amplitude than non-broad-line (NL) AGNs, with ∼80% of the BL AGNs classified as variable, while only ∼21% of the NL AGNs are classified as variable. We also find that ∼22% of objects classified as galaxies (GALs) are also variable. The determination and parameterization of the structure function ( ) of the variable sources show that most BL AGNs are characterized by and . It is further shown that NL AGNs and GAL sources occupying the same parameter space in A and γ are very likely to correspond to obscured or low-luminosity AGNs. Our samples are, however, small, and we expect to revisit these results using larger samples with longer light curves obtained as part of our ongoing survey.
Source: The Astrophysical Journal
Authors: Régis Cartier, Paulina Lira, Paolo Coppi, Paula Sánchez, Patricia Arévalo, Franz E. Bauer, David Rabinowitz, Robert Zinn, Ricardo R. Muñoz, Nicolás Meza
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Yale University, Princeton University, Ohio State University, University of Washington, Johns Hopkins University, University of Pittsburgh, Case Western Reserve University, Drexel University, Universität Basel, University of Portsmouth, New Mexico State University, Chinese Academy of Sciences, Max-Planck-Gesellschaft, Max-Planck-Institut für Astronomie, Comisión Nacional de Investigación Científica y Tecnológica, U.S. Naval Observatory, Fermilab, Los Alamos National Laboratory
OpenAlex ID: W2154020249