GASP XXVII: Gas-phase metallicity scaling relations in disk galaxies
  with and without ram-pressure stripping
  Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE
(GASP) survey, we study the gas-phase metallicity scaling relations of a sample
of 29 cluster galaxies undergoing ram-pressure stripping and of a reference
sample of (16 cluster and 16 field) galaxies with no significant signs of gas
disturbance. We adopt the PYQZ code to infer the mean gas metallicity at the
effective radius and achieve a well-defined mass-metallicity relation (MZR) in
the stellar mass range $10^{9.25}\le M_\star \le 10^{11.5}\,{\rm M_\odot}$ with
a scatter of 0.12 dex. At any given mass, reference cluster and stripping
galaxies have similar metallicities, while the field galaxies with $M_\star <
10^{10.25}\,{\rm M_\odot}$ show on average lower gas metallicity than galaxies
in clusters. Our results indicate that at the effective radius the chemical
properties of the stripping galaxies are independent of the ram-pressure
stripping mechanism. Nonetheless, at the lowest masses we detect 4 stripping
galaxies well above the common MZR that suggest a more complex scenario.
Overall, we find signs of an anti-correlation between the metallicity and both
the star formation rate and the galaxy size, in agreement with previous
studies. No significant trends are instead found with the halo mass,
clustercentric distance and local galaxy density in clusters. In conclusion, we
advise a more detailed analysis of the spatially resolved gas metallicity maps
of the galaxies, able to highlight effects of gas redistribution inside the
disk due to the ram-pressure stripping.
