Chandra observations of the hybrid morphology radio sources 3C 433 and 4C 65.15: FR IIs with asymmetric environments

TL;DR

This study uses Chandra X-ray observations to analyze two hybrid morphology radio sources, revealing details about their asymmetric environments, jet structures, and X-ray emissions, which enhance understanding of FR I/II galaxy characteristics.

Contribution

First detailed X-ray analysis of hybrid FR I/II radio sources, showing environmental effects on jet morphology and emission properties.

Findings

3C 433 shows intrinsic absorption typical of FR II galaxies.

4C 65.15's X-ray emission suggests a concave spectral energy distribution.

Both sources exhibit properties consistent with FR II morphology despite asymmetry.

Abstract

We present Chandra observations of the hybrid morphology radio sources 3C 433 and 4C 65.15, two members of the rare class of objects possessing an FR I jet on one side of the core and an FR II lobe on the other. The X-ray spectrum of 3C 433 shows intrinsic absorption (with a column density of N_H=8e22 cm-2), such as is typical of FR II narrow-line radio galaxies. There is excess X-ray emission below 2 keV containing contributions from diffuse soft X-ray emission (likely hot gas with kT~1.2 keV) as well as from the nucleus. The core of 3C 433 is extended in hard X-rays, presumably due to X-ray emission from the inner-jet knot on the FR I side that is apparent in the radio map. It is possible that the X-ray emission from this inner-jet knot is absorbed by the dust known to be present in the host galaxy. The spectrum of 4C 65.15 can be modeled with a simple power law with perhaps mild intrinsic absorption (N_H=1.3e21 cm-2). X-ray emission is detected at the bend in the FR I jet. This X-ray jet emission lies above the extrapolation from the high-frequency radio synchrotron emission and has a spectral slope flatter than alpha_rx, indicating that the jet spectral energy distribution is concave as with other FR II quasar jets. Both 3C 433 and 4C 65.15 have unabsorbed X-ray luminosities, radio luminosities, and optical spectra typically seen in comparable sources with FR II morphologies. Presumably the FR I structure seen on one side in these hybrid sources is generated by a powerful jet interacting with a relatively dense environment.