X-ray Observations of radio Jets from 3CR 14 and 3CR 9

Abstract

Jets from active galaxies can interact with the interstellar medium of a galaxy to change the evolution of the host galaxy and surrounding gas. Studying the mechanisms responsible for creating X-ray photons can paint a picture of the magnetic environment at the terminus of the jet. X-ray observations are needed to determine the internal magnetic field and thus remove the assumption of minimum energy which in some cases is not a sufficient approximation. The core of 3CR 14 has a flat spectrum of Γ=1.464±0.073 and high luminosity of L_{0.3-8.0 kev}=6.3±0.2×10⁴⁴ erg s^-1.  The radio-linked lobe emission shows a dominance of inverse Compton scattering of the cosmic microwave background emission generating
 the X-ray emission as opposed to inverse Compton from synchrotron. The ratio of flux densities is f_iC/CMB/f_SSC ≈ 10 with infrared data confirming there is no direct synchrotron contribution. Modelling shows the magnetic field is consistent with the modelled minimum energy magnetic field in the jet lobes. An X-ray hot spot selected due to a significant grouping of X-ray counts that have coincided with a secondary radio hot spot reveals a magnetic field below equipartition with a ratio B_ME/B_int=3. Observation of 3CR 14 with Chandra has revealed a clear region of extended emission to the east of the AGN core. This emission is unmatched in radio, infrared or optical emission and is perpendicular to the known AGN jets which run north and south. This region is likely due to hot gas contracting back towards the AGN core after it had been pushed out by the AGN jets as the jets exited the host galaxy. 3CR 9 has been selected as an active galaxy to analyse alongside 3CR 14. This galaxy has a much smaller jet-span on the plane of the sky and no obvious extension aside from jet related emission. 3CR 9 has a moderate but somewhat flat spectrum of Γ=1.797±0.058 and a luminosity of L_{0.3-8.0 kev}=3.2±0.1×10⁴³ erg s^-1. The southern lobe and hot spot have a significant contribution of inverse Compton scattering from synchrotron radiation contributing to the X-ray emission which is likely most important in the hot spot region with ratios f_iC/CMB/f_SSC ≈ 4 and f_iC/CMB/f_SSC ≈ 2 respectively; the magnetic field of these regions are consistent with minimum energy. The northern lobe and hot spot contrast this with negligible scattering from synchrotron radiation with ratios f_iC/CMB/f_SSC ≈ 105 and f_iC/CMB/f_SSC ≈ 37 respectively. Both the northern lobe and hot spot are out of a state of minimum energy by a factor of 3.

Date of Award	23 Jan 2024
Original language	English
Awarding Institution	University of Bristol
Supervisor	Belinda Wilkes (Supervisor), Mark Birkinshaw (Supervisor), Andrew J Young (Supervisor) & Ben J Maughan (Supervisor)