Optical variability of quasars with 20-yr photometric light curves
Abstract
We study the optical gri photometric variability of a sample of 190 quasars within the SDSS Stripe 82 region that have long-term photometric coverage during ∼1998−2020 with SDSS, PanSTARRS-1, the Dark Energy Survey, and dedicated follow-up monitoring with Blanco 4m/DECam. With on average ∼200 nightly epochs per quasar per filter band, we improve the parameter constraints from a Damped Random Walk (DRW) model fit to the light curves over previous studies with 10–15 yr baselines and ≲ 100 epochs. We find that the average damping time-scale τDRW continues to rise with increased baseline, reaching a median value of ∼750 d (g band) in the rest frame of these quasars using the 20-yr light curves. Some quasars may have gradual, long-term trends in their light curves, suggesting that either the DRW fit requires very long baselines to converge, or that the underlying variability is more complex than a single DRW process for these quasars. Using a subset of quasars with better-constrained τDRW (less than 20 per cent of the baseline), we confirm a weak wavelength dependence of τDRW∝λ0.51 ± 0.20. We further quantify optical variability of these quasars over days to decades time-scales using structure function (SF) and power spectrum density (PSD) analyses. The SF and PSD measurements qualitatively confirm the measured (hundreds of days) damping time-scales from the DRW fits. However, the ensemble PSD is steeper than that of a DRW on time-scales less than ∼ a month for these luminous quasars, and this second break point correlates with the longer DRW damping time-scale.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 18, 2022
- Source ID
- 10.1093/mnras/stac1259
Entities
People
- (des Collaboration)
- A Carnero Rosell
- A Pieres
- Andrés A. Plazas Malagón
- C To
- Chris Lidman
- Colin J. Burke
- D N Friedel
- D. J. James
- D. L. Burke
- Daniel Gruen
- Daniel I. Brooks
- David Bacon
- Devon Hollowood
- E. R. Sánchez
- Emmanuel Bertin
- Enrique Gaztañaga
- Eric Suchyta
- F Andrade-oliveira
- F Menanteau
- F Paz-chinchón
- G Tarlé
- G. Gutierrez
- H T Diehl
- I Sevilla-noarbe
- Ismael Ferrero
- J Annis
- J De Vicente
- J Frieman
- Jorge Carretero Palacios
- Juan García-Bellido
- K Honscheid
- K Kuehn
- L N Da Costa
- M A G Maia
- M Carrasco Kind
- M E C Swanson
- M E S Pereira
- M. Rodríguez-Monroy
- Mathew Smith
- Monika Adamów
- Nikolay Kuropatkin
- P Doel
- Qian Yang
- R A Gruendl
- R Miquel
- Robert W. Morgan
- S Serrano
- S. Bocquet
- Samuel R Hinton
- Shruti Desai
- V Scarpine
- Xin Liu
- Yu-Ching Chen
- Yue Shen
- Zachary Stone
Organizations
- Australian National University
- Autonomous University of Barcelona
- Autonomous University of Madrid
- Barcelona Institute for Science and Technology
- Case Western Reserve University
- Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
- Chinese Academy of Sciences
- Drexel University
- Fermilab
- Financiadora de Estudos e Projetos
- Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
- Harvard–Smithsonian Center for Astrophysics
- Higher Education Funding Council for England
- Indian Institute of Technology Hyderabad
- Institute for Advanced Study
- Institute of Space Studies of Catalonia
- Johns Hopkins University
- Lawrence Berkeley National Laboratory
- Los Alamos National Laboratory
- Lowell Observatory
- Ludwig-Maximilians-Universität München
- Ministry of Science, Technology and Innovation
- National Council for Scientific and Technological Development
- National Science Foundation
- New Mexico State University
- Oak Ridge National Laboratory
- Ohio State University
- Princeton University
- SLAC National Accelerator Laboratory
- Santa Cruz Institute for Particle Physics
- Science and Technology Facilities Council
- Sorbonne University
- Spanish National Research Council
- Stanford University
- São Paulo State University
- Texas A&M University
- United States Department of Energy
- United States Naval Observatory
- University College London
- University of Basel
- University of Cambridge
- University of Chicago
- University of Hamburg
- University of Illinois Urbana–Champaign
- University of Michigan
- University of Nottingham
- University of Oslo
- University of Pennsylvania
- University of Pittsburgh
- University of Portsmouth
- University of Queensland
- University of Southampton
- University of Sussex
- University of Washington
- University of Wisconsin–Madison