The Chandra View of Nearby X-shaped Radio Galaxies

TL;DR

This study uses Chandra X-ray data to analyze the hot gas environments of X-shaped radio galaxies, finding that their wings align with the minor axis of the hot gas, supporting hydrodynamic formation models.

Contribution

The paper provides the first detailed X-ray analysis of hot gas in X-shaped radio galaxies, linking their morphology to the hot gas distribution and supporting specific formation theories.

Findings

X-shaped radio galaxy wings align with the minor axis of hot gas.

Hot gas ellipticity and stellar light distribution are correlated.

Results support hydrodynamic backflow models over reorientation models.

Abstract

We present new and archival Chandra X-ray Observatory observations of X-shaped radio galaxies within z < 0.1 alongside a comparison sample of normal double-lobed FR I and II radio galaxies. By fitting elliptical distributions to the observed diffuse hot X-ray emitting atmospheres, we find that the ellipticity and the position angle of the hot gas follows that of the stellar light distribution for radio galaxy hosts in general. Moreover, compared to the control sample, we find a strong tendency for X-shaped morphology to be associated with wings directed along the minor axis of the hot gas distribution. Taken at face value, this result favors the hydrodynamic backflow models for the formation of X-shaped radio galaxies which naturally explain the geometry; the merger-induced rapid reorientation models make no obvious prediction about orientation.