2018/03/27 by Sheng-Chu Guo, Hai-Ming Zhang, Jin Zhang +2
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmic microwave background #Equipartition theorem #Fermi Gamma-ray Space Telescope #Galaxies: Formation, Evolution, Phenomena #Galaxy #Knot (papermaking) #Magnetic field #Optics #Physics #Radio Astronomy Observations and Technology #Radio galaxy #Radio spectrum #Spectral energy distribution #Synchrotron #Synchrotron radiation #astro-ph.HE
paper · pdf · doi:10.1088/1674-4527/18/6/70
7 pages, 2 figures, accepted for publication in RAA
arxiv created 2018/03/27 · openalex created_date 2018/04/06 · openalex publication_date 2018/06/01 · arxiv updated 2018/06/13 · openalex updated_date 2026/08/06
Abstract 3C 207 is a lobe-dominant radio galaxy with a one sided jet and bright knots, spanning a kpc-Mpc scale, which have been resolved in the radio, optical and X-ray bands. This target was confirmed as a γ -ray emitter with Fermi /LAT, but it is uncertain whether the γ -ray emission region is the core or knots due to the low spatial resolution of Fermi /LAT. We present an analysis of its Fermi /LAT data acquired during the past 9 years. Different from the radio and optical emission from the core, it is found that the γ -ray emission is steady without detection of flux variation at over a 2 σ confidence level. This likely implies that the γ -ray emission is from its knots. We collect the radio, optical and X-ray data of knot-A, the closest knot from the core at 1.4″, and compile its spectral energy distribution (SED). Although the single-zone synchrotron+SSC+IC/CMB model that assumes knot-A is at rest can reproduce the SED in the radio-optical-X-ray band, the predicted γ -ray flux is lower than the LAT observations and the derived magnetic field strength deviates from the equipartition condition by 3 orders of magnitude. Assuming that knot-A is moving relativistically, its SED from radio to γ -ray bands would be represented well with the single-zone synchrotron+SSC+IC/CMB model under the equipartition condition. These results likely suggest that the γ -ray emission may be from knot-A via the IC/CMB process and the knot should have relativistical motion. The jet power derived from our model parameters is also roughly consistent with the kinetic power estimated with radio data.