LoTSS jellyfish galaxies: I. Radio tails in low redshift clusters
  In this paper we present a large sample of jellyfish galaxies in low redshift
clusters (z<0.05), identified through 120-168 MHz radio continuum from the
LOFAR Two-metre Sky Survey (LoTSS). From a parent sample of 29 X-ray-detected
SDSS galaxy clusters and their spectroscopic members, we visually identify 95
star-forming, LoTSS jellyfish galaxies with 144 MHz radio tails. Star formation
rates (SFRs) and stellar masses are obtained for all galaxies from SED fits.
For each jellyfish galaxy we determine the tail orientation with respect to the
cluster centre and quantify the prominence of the radio tails with the 144 MHz
shape asymmetry. After carefully accounting for redshift-dependent selection
effects, we find that the frequency of jellyfish galaxies is relatively
constant from cluster to cluster. LoTSS jellyfish galaxies are preferentially
found at small clustercentric radius and large velocity offsets within their
host clusters and have radio tails that are oriented away from the cluster
centre. These galaxies also show enhanced star formation, relative to both
'normal' cluster galaxies and isolated field galaxies, but generally fall
within the scatter of the L144MHz - SFR relation. The properties of the LoTSS
jellyfish galaxies identified in this work are fully consistent with
expectations from ram pressure stripping. This large sample of jellyfish
galaxies will be valuable for further constraining ram pressure stripping and
star formation quenching in nearby galaxy clusters. We show that LOFAR is a
powerful instrument for identifying ram pressure stripped galaxies across
extremely wide fields. Moving forward we will push the search for jellyfish
galaxies beyond this initial cluster sample, including a comprehensive survey
of the galaxy group regime.
