Multiwavelength Temporal Variability of the Blazar PKS 1510–089

• Published in: The Astrophysical journal Vol. 953; no. 1; pp. 47 - 61
• Main Authors: Yuan, Q., Kushwaha, Pankaj, Gupta, Alok C., Tripathi, Ashutosh, Wiita, Paul J., Zhang, M., Liu, X., Lähteenmäki, Anne, Tornikoski, Merja, Tammi, Joni, Ramakrishnan, Venkatessh, Cui, L., Wang, X., Gu, M. F., Bambi, Cosimo, Volvach, A. E.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01-08-2023; IOP Publishing
• Subjects: Active galactic nuclei; Astrophysics; Blazars; Correlation; Emission analysis; Flat-spectrum radio quasars; Gamma rays; Light curve; Near infrared radiation; Observational astronomy; Observatories; Quasars; Radiation; Radio telescopes; Telescopes; Temporal variability; Wavelengths; Z transforms
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/acdd74

Abstract
We perform correlation and periodicity search analyses on long-term multiband light curves of the flat-spectrum radio quasar PKS 1510−089 observed by the space-based Fermi-Large Area Telescope in
γ
-rays, the SMARTS and Steward Observatory telescopes in optical and near-infrared (NIR), and the 13.7 m radio telescope in Metsähovi Radio Observatory between 2008 and 2018. The
z
-transform discrete correlation function method is applied to study the correlation and possible time lags among these multiband light curves. Among all pairs of wavelengths, the
γ
-ray versus optical/NIR and optical versus NIR correlations show zero time lags; however, both the
γ
-ray and optical/NIR emissions precede the radio radiation. The generalized Lomb–Scargle periodogram, weighted wavelet
z
-transform, and REDFIT techniques are employed to investigate the unresolved core emission–dominated 37 GHz light curve and yield evidence for a quasi period around 1540 days, although given the length of the whole data set it cannot be claimed to be significant. We also investigate the optical/NIR color variability and find that this source shows a simple redder-when-brighter behavior over time, even in the low-flux state.