  We report on the detection of diffuse radio emission with peculiar morphology
in the central region of the galaxy cluster Abell 2657. The most striking
feature identified in our 144 MHz LOFAR image is a bifurcated radio arc that
extends for a projected size of 150-200 kpc. From the analysis of XMM-Newton
data, we find clear evidence of gas sloshing in the cluster and a possible dip
in X-ray surface brightness between the two radio arcs which deserves
confirmation. Interestingly, the synchrotron emission of the bifurcated radio
arc is stretched along the sloshing spiral. We compare our observational
results with numerical simulations of non-thermal components interacting with
gas motions. We suggest that the detected emission may trace a radio bubble
shredded by gas sloshing, where relativistic electrons and magnetic fields are
expected to be stretched and stirred as a consequence of tangential flows
induced by the spiralling gas motion. Lastly, we report on the presence of two
thin (6-7 kpc in width) and parallel strands of radio emission embedded in the
outer arc that are morphologically similar to the emerging population of
non-thermal filaments observed in galaxy clusters, radio galaxies, and the
Galactic centre. While this work further demonstrates the complex interplay
between thermal and non-thermal components in the intracluster medium,
follow-up observations in radio and X-rays are required to firmly determine the
origin of the features observed in Abell 2657.
