Testing for Shock-Heated X-ray Gas Around Compact Steep Spectrum Radio Galaxies

TL;DR

This study investigates X-ray emissions from three CSS radio galaxies using Chandra and XMM-Newton, finding evidence of shock-heated gas in some cases, and compiles properties of nine CSS galaxies with X-ray detections.

Contribution

It provides new X-ray observations of three CSS radio galaxies and suggests hot shocked gas may be common in CSS sources, expanding understanding of their interaction with host galaxies.

Findings

2 out of 9 CSS galaxies show X-ray evidence of hot shocked gas

X-ray properties of the studied CSS galaxies are consistent with shock-heated ISM

Hot shocked gas may be typical in CSS radio galaxies due to their propagation through host galaxies

Abstract

We present Chandra and XMM-Newton X-ray, VLA radio, and optical observations of three candidate Compact Steep Spectrum (CSS) radio galaxies. CSS sources are galactic scale and are presumably driving a shock through the ISM of their host galaxy. B3 1445+410 is a low excitation emission line CSS radio galaxy with possibly a hybrid Fanaroff-Riley FRI/II (or Fat Double) radio morphology. The Chandra observations reveal a point-like source which is well fit with a power law consistent with emission from a Doppler boosted core. 3C 268.3 is a CSS broad line radio galaxy whose Chandra data are consistent spatially with a point source centered on the nucleus and spectrally with a double power-law model. PKS B1017-325 is a low excitation emission line radio galaxy with a bent double radio morphology. While from our new spectroscopic redshift, PKS B1017-325 falls outside the formal definition of a CSS, the XMNM-Newton observations are consistent with ISM emission with either a contribution from hot shocked gas or non-thermal jet emission. We compile selected radio and X-ray properties of the nine bona fide CSS radio galaxies with X-ray detections so far. We find that 2/9 show X-ray spectroscopic evidence for hot shocked gas. We note that the counts in the sources are low and the properties of the 2 sources with evidence for hot shocked gas are typical of the other CSS radio galaxies. We suggest that hot shocked gas may be typical of CSS radio galaxies due to their propagation through their host galaxies.