ﻻ يوجد ملخص باللغة العربية
We present cross-correlation studies of gamma-ray (0.1-300 GeV), X-ray (0.2-10 keV) and optical (R-band) variability of a sample of 26 blazars during 2008-2016. The light curves are from Fermi-LAT, Swift-XRT, and the Yale-SMARTS blazar monitoring program. We stack the discrete cross-correlation functions of the blazars such that the features that are consistently present in a large fraction of the sample become more prominent in the final result. We repeat the same analysis for two subgroups, namely, low synchrotron peaked (LSP) and high synchrotron peaked (HSP) blazars. We find that, on average, the variability at multiple bands is correlated, with a time lag consistent with zero in both subgroups. We describe this correlation with a leptonic model of non-thermal emission from blazar jets. By comparing the model results with those from the actual data we find that the inter-band cross-correlations are consistent with an emission region of size nearly 0.1 pc within the broad line region for LSP blazars. We rule out large changes of magnetic field (> 0.5 Gauss) across the emission region or small values of magnetic field (e.g. 0.2 Gauss) for this population. We also find that the observed variability of the HSP blazars can be explained if the emission region is much larger than the distance to the broad line region from the central black hole.
We present the time variability properties of a sample of six blazars, AO 0235+164, 3C 273, 3C 279, PKS 1510-089, PKS 2155-304, and 3C 454.3, at optical-IR as well as gamma-ray energies. These observations were carried out as a part of the Yale/SMART
We present $gamma$-ray, X-ray, ultraviolet, optical, and near-infrared light curves of 33 $gamma$-ray bright blazars over four years that we have been monitoring since 2008 August with multiple optical, ground-based telescopes and the Swift satellite
We use optical data from the Palomar Transient Factory (PTF) and the Catalina Real-Time Transient Survey (CRTS) to study the variability of gamma-ray detected and non-detected objects in a large population of active galactic nuclei (AGN) selected fro
We present average R-band optopolarimetric data, as well as variability parameters, from the first and second RoboPol observing season. We investigate whether gamma- ray--loud and gamma-ray--quiet blazars exhibit systematic differences in their optic
Blazars are a subclass of active galactic nuclei (AGNs) with extreme observation properties, which is caused by the beaming effect, expressed by a Doppler factor, in a relativistic jet. Doppler factor is an important parameter in the blazars paradigm