The Spatially Resolved Mass-Metallicity Relation in Mergers

In the global galaxy stellar mass-metallicity relation (MZR), it has been found that interacting galaxies have reduced metallicities compared to similar-mass isolated counterparts. In this work, we validate this relation at the spatially resolved level, and investigate the spatially resolved MZR in galaxy pairs in the SDSS-MaNGA survey, by comparing the stellar mass surface density \( \Sigma _{*}\) , and the metallicity abundance, \(12 + \log \text {(O/H),}\) for star-forming spaxels belonging to 298 galaxy pairs in SDSS-MaNGA, with the star-forming spaxels identified using emission line diagnostics. We use a multi-step identification method combining visual inspection and pair finding to find interacting galaxies. We also investigate if (a) the location of a spaxel relative to the galaxy centre and (b) the galaxy pair separation have any effect on the local MZR, to understand where chemical evolution may occur in interacting galaxy systems. We find a bimodel distribution of spaxels. One peak has diluted metallicity, which shows that the correlation between mass and metallicity for interacting galaxies is consistent between the global and local level for some spaxels. However, another peak has metallicities lying on the MZR for the entire MaNGA sample. We find that the spaxels belonging to the galaxy central regions (i.e. at lower \(R/R_{\text {eff}}\) ) are concentrated close to the two peaks. We additionnally investigate if any relationship exists between MZR loci and galaxy pair separation, and find that close galaxy pairs have spaxels with diluted metallicities, and pairs with greater separations have spaxels with metallicities consistent with the MZR belong to galaxy pairs with greater projected separations.