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Review

30 Years of Multifrequency Quasar Variability: A Personal Journey

SARA Observatory, Stocker Astroscience Center, Department of Physics, Florida International University, Miami, FL 33185, USA
Academic Editor: Alicja Wierzcholska
Galaxies 2021, 9(4), 69; https://doi.org/10.3390/galaxies9040069
Received: 13 July 2021 / Revised: 24 August 2021 / Accepted: 12 September 2021 / Published: 22 September 2021
(This article belongs to the Special Issue Multi-Messenger and Multi-Timescale Variability in Blazars)
I outline the history of and progress in observing and understanding quasar multi-frequency and multi-messenger variability from the point of view of someone who has been working in the field for over 30 years. I will present some important references for the evolution from optical monitoring to multi-frequency cooperative programs that revealed the true multi-frequency/multi-timescale nature of variability in these objects. Quasar observations began with separate radio and optical monitoring programs; then the optical and radio observations w ere combined. This was followed by expanding the analyses to include far IR, UV, X-rays, and finally adding gamma rays. This progression yielded simultaneous multi-frequency spectra of these objects and light curves over 15 decades in frequency. The future is adding particle (neutrino) and gravitational waves to the picture. I also present long-term (50 years) optical light curves, and discuss optical variability at all timescales from minutes to tens of years in some selected objects for which we have reliable long-term monitoring observations.
Keywords: Blazars; optical variability; multifrequency variability; SARA Consortium; Smarts facility Blazars; optical variability; multifrequency variability; SARA Consortium; Smarts facility
MDPI and ACS Style

Webb, J.R. 30 Years of Multifrequency Quasar Variability: A Personal Journey. Galaxies 2021, 9, 69. https://doi.org/10.3390/galaxies9040069

AMA Style

Webb JR. 30 Years of Multifrequency Quasar Variability: A Personal Journey. Galaxies. 2021; 9(4):69. https://doi.org/10.3390/galaxies9040069

Chicago/Turabian Style

Webb, James R. 2021. "30 Years of Multifrequency Quasar Variability: A Personal Journey" Galaxies 9, no. 4: 69. https://doi.org/10.3390/galaxies9040069

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