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Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2022

Optical variability of quasars with 20-yr photometric light curves

Zachary Stone
  • Function : Author
Yue Shen
  • Function : Author
Colin J. Burke
  • Function : Author
Yu-Ching Chen
  • Function : Author
Qian Yang
  • Function : Author
Xin Liu
  • Function : Author
R. A. Gruendl
  • Function : Author
M. Adamów
  • Function : Author
F. Andrade-Oliveira
  • Function : Author
J. Annis
  • Function : Author
D. Bacon
  • Function : Author
S. Bocquet
  • Function : Author
D. Brooks
  • Function : Author
D. L. Burke
  • Function : Author
A. Carnero Rosell
  • Function : Author
M. Carrasco Kind
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J. Carretero
  • Function : Author
L. N. da Costa
  • Function : Author
M. E. S. Pereira
  • Function : Author
J. de Vicente
  • Function : Author
S. Desai
  • Function : Author
H. T. Diehl
  • Function : Author
P. Doel
  • Function : Author
I. Ferrero
  • Function : Author
D. N. Friedel
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J. Frieman
  • Function : Author
J. García-Bellido
  • Function : Author
E. Gaztanaga
  • Function : Author
D. Gruen
  • Function : Author
G. Gutierrez
  • Function : Author
S. R. Hinton
  • Function : Author
D. L. Hollowood
  • Function : Author
K. Honscheid
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D. J. James
  • Function : Author
K. Kuehn
  • Function : Author
N. Kuropatkin
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C. Lidman
  • Function : Author
M. A. G. Maia
  • Function : Author
F. Menanteau
  • Function : Author
R. Miquel
  • Function : Author
R. Morgan
  • Function : Author
F. Paz-Chinchón
  • Function : Author
A. Pieres
  • Function : Author
A. A. Plazas Malagón
  • Function : Author
M. Rodriguez-Monroy
  • Function : Author
E. Sanchez
  • Function : Author
V. Scarpine
  • Function : Author
S. Serrano
  • Function : Author
I. Sevilla-Noarbe
  • Function : Author
M. Smith
  • Function : Author
E. Suchyta
  • Function : Author
M. E. C. Swanson
  • Function : Author
G. Tarlé
  • Function : Author
C. To
  • Function : Author

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.
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Dates and versions

insu-03748242 , version 1 (12-04-2023)

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Zachary Stone, Yue Shen, Colin J. Burke, Yu-Ching Chen, Qian Yang, et al.. Optical variability of quasars with 20-yr photometric light curves. Monthly Notices of the Royal Astronomical Society, 2022, 514, pp.164-184. ⟨10.1093/mnras/stac1259⟩. ⟨insu-03748242⟩
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