Affiliation:
1. Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai 264209, China
2. School of Space Science and Physics, Shandong University, Weihai 264209, China
Abstract
Variability study at multi-frequency provides us with rich information of the emission and variation mechanism for blazars. In this work, we present a comprehensive multi-frequency analysis of the high-synchrotron-peaked (HSP) blazar Mrk 501, using γ-ray, X-ray, optical, optical polarization, and radio data. The multiple-wavelength light curves are analyzed by using the localized cross-correlation function to derive locations of their emitting regions. The X-ray, γ-ray, and optical emitting regions are found to be upstream of the radio core region, while the X-ray and γ-ray emitting regions likely coincide. We studied the variation behaviors for three long-term (years), five relatively short-term (months) periods. We find a positive correlation between the optical and X-ray fluxes, and conclude that the variable of Doppler factor is not favored for the one-zone SSC scenario. The study also identifies the existence of a soft γ-ray background in the low-activity state, which could be explained by the spine/layer jet model. Our study on Mrk 501 provides valuable insights to understand the emission processes and variation mechanism for HSP blazars.
Funder
National Natural Science Foundation of China
Shandong Provincial Natural Science Foundation
Reference45 articles.
1. Unified Schemes for Radio-Loud Active Galactic Nuclei;Urry;Publ. Astron. Soc. Pac.,1995
2. Variability of Active Galactic Nuclei;Ulrich;Annu. Rev. Astron. Astrophys.,1997
3. Are high polarization quasars and BL Lacertae objects really different? A study of the optical spectral properties;Scarpa;Astron. Astrophys.,1997
4. The Spectral Energy Distribution of Fermi Bright Blazars;Abdo;Astrophys. J.,2010
5. Galaxies with ultraviolet continuum: V;Markarian;Astrofizika,1972