Exploring the origin of broad-band emissions of Mrk 501 with a two-zone model

PASJ: Publications of the Astronomical Society of Japan

Wang, Jiancheng¹  Yang, Chuyuan²  Lei, Maichang³  Yang, Xiaolin³ 

[1] Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, 100012, China;Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011, China;Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China

关键词: galaxies: active;    (galaxies:) BL Lacertae objects: individual;    galaxies: jets;    radiation mechanisms: general;   

DOI  :  10.1093/pasj/psy035

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We propose a two-zone synchrotron self-Compton (SSC) model, including an inner gamma-ray emitting region with spherical shape and a conical radio emitting region located at the extended jet, to alleviate the long-standing “bulk Lorentz factor crisis” in blazars. In this model, the spectral energy distributions (SEDs) of blazars are produced by considering the gamma-ray emitting region inverse Compton scattering of both the synchrotron photons itself and the ambient photons from the radio emitting region. Applying the model to Mrk 501, we obtain that the radio emitting region has a comoving length of ∼0.15 pc and is located at sub-parsec scale from the central engine by modeling the radio data; the flux of the Compton scattering of the ambient photons is so low that it can be neglected safely. The characteristic hard gamma-ray spectrum can be explained by the superposition of two SSC processes, and the model can approximately explain the very high energy (VHE) data. The insights into the spectral shape and the inter-band correlations under the flaring state will provide us with a diagnostic for the bulk Lorentz factor of radio emitting region, where the low and upper limits of 8 and 15 are preferred, and for the two-zone SSC model itself. In addition, our two-zone SSC model shows that the gamma-ray emitting region creates flare on the timescale of merely a few hours, and the long time outbursts more likely originate from the extended radio emitting region.

【 授权许可】

CC BY