Multifrequency JVLA observations of the X-shaped radio galaxy in Abell
  3670
  Context. X-shaped radio galaxies (XRGs) exhibit a pair of bright primary
lobes and a pair of weak secondary lobes (wings), which are oriented with an
angle that gives the structure a cross-like shape. Though several theoretical
models have been proposed to explain their origin, there is currently not a
general consensus on a formation scenario. Aims. We analysed new multifrequency
Karl G. Jansky Very Large Array (JVLA) radio data at 1.5, 5.5, 6, and 9 GHz of
the candidate XRG in Abell 3670 (A3670) in order to characterise and classify
it for the first time and to investigate its origin. Methods. We produced flux,
spectral index, and radiative age maps of A3670 by means of the new radio data.
We investigated the connection between the radio galaxy and its host, a
brightest cluster galaxy (BCG) with two optical nuclei classified as a dumbbell
galaxy. Finally we discussed the literature models and compared them to the
observed properties of A3670. Results. We classify A3670 as a Fanaroff-Riley
I-type XRG and measured a 1.4 GHz radio power of 1.7 x 10^25 W Hz-1. By
estimating the radiative age of the various source components, we find that the
wings are 20 Myr older than the lobes. We verified that the lobes and wings are
aligned with the major and minor axes of the optical galaxy, respectively, and
we estimated a black hole mass of 10^9 Msun , which is in agreement with the
typical properties of the XRGs. Conclusions. Among the discussed scenarios, the
jet-shell interaction model may best reproduce the observed properties of
A3670. The gas of a stellar shell is responsible for the deflection of the
jets, thus forming the wings. The presence of stellar shells in A3670 is
plausible, but it needs further optical observations to be confirmed.
