TY - JOUR

T1 - Correlation analysis of delays between variations of Gamma-Ray and optical light curves of blazars

AU - Williamson, Karen E.

AU - Jorstad, Svetlana G.

AU - Marscher, Alan P.

AU - Larionov, Valeri M.

AU - Agudo, Iván

AU - Arkharov, Arkady A.

AU - Blinov, Dmitry A.

AU - Casadio, Carolina

AU - Gómez, José L.

AU - Hagen-Thorn, Vladimir A.

AU - Joshi, Manasvita

AU - Konstantinova, Tatiana S.

AU - Kopatskaya, Evgenia N.

AU - Larionova, Elena G.

AU - Larionova, Liudmilla V.

AU - Malmrose, Michael P.

AU - McHardy, Ian M.

AU - Molina, Sol N.

AU - Morozova, Daria A.

AU - Taylor, Brian W.

AU - Troitsky, Ivan S.

N1 - Publisher Copyright: © 2016 by the authors. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.

PY - 2016/12/1

Y1 - 2016/12/1

N2 - We have been performing multi-wavelength monitoring of a sample of -ray blazars since the launch of the Fermi Gamma-ray Space Telescope in 2008. We present -ray and optical light curves for several quasars and BL Lac objects from the sample to illustrate different patterns of variability. We investigate correlations between -ray and R-band light curves and, if these are statistically significant, determine delays between variations at the two wavebands. Such time delays can reveal the relative locations of the emitting regions in AGN jets and the origin of the high-energy photons. We present preliminary results of this analysis. Of the 29 blazars with sufficient time coverage, 17 display a significant, singular, correlated time lag when tested over the entire 7-year period. Of these sources, the six that exhibit a consistent time lag across a majority of epochs of high activity have lags of 0 ± 7 days; the 11 without consistency across epochs of high activity generally display longer mean lags, with γ-ray leading optical. Eleven sources display no significant singular correlation over either the entire 7-year period or across shorter intervals. No significant difference is apparent between the BL Lac objects and FSRQs. Even after 7 years of monitoring, our correlation analysis remains plagued with uncertainties due to insufficient data.

AB - We have been performing multi-wavelength monitoring of a sample of -ray blazars since the launch of the Fermi Gamma-ray Space Telescope in 2008. We present -ray and optical light curves for several quasars and BL Lac objects from the sample to illustrate different patterns of variability. We investigate correlations between -ray and R-band light curves and, if these are statistically significant, determine delays between variations at the two wavebands. Such time delays can reveal the relative locations of the emitting regions in AGN jets and the origin of the high-energy photons. We present preliminary results of this analysis. Of the 29 blazars with sufficient time coverage, 17 display a significant, singular, correlated time lag when tested over the entire 7-year period. Of these sources, the six that exhibit a consistent time lag across a majority of epochs of high activity have lags of 0 ± 7 days; the 11 without consistency across epochs of high activity generally display longer mean lags, with γ-ray leading optical. Eleven sources display no significant singular correlation over either the entire 7-year period or across shorter intervals. No significant difference is apparent between the BL Lac objects and FSRQs. Even after 7 years of monitoring, our correlation analysis remains plagued with uncertainties due to insufficient data.

KW - BL Lacertae objects: general

KW - Galaxies: active

KW - Galaxies: jets

KW - Quasars: general

UR - http://www.scopus.com/inward/record.url?scp=85054282590&partnerID=8YFLogxK

U2 - 10.3390/galaxies4040064

DO - 10.3390/galaxies4040064

M3 - Article

AN - SCOPUS:85054282590

VL - 4

JO - Galaxies

JF - Galaxies

SN - 2075-4434

IS - 4

M1 - 64

ER -