Exploring the AGN-Ram Pressure Stripping Connection in Local Clusters

Ram pressure stripping (RPS) by the intracluster medium is one of the most advocated mechanisms that affect the properties of cluster galaxies. A recent study based on a small sample has found that many galaxies showing strong signatures of RPS also possess an active galactic nucleus (AGN), suggesting a possible correlation between the two phenomena. This result has not been confirmed by a subsequent study. Building upon previous findings, here we combine MUSE observations conducted within the GASP program and a general survey of the literature to robustly measure the AGN fraction in ram-pressure-stripped cluster galaxies using Baldwin-Phillips-Terlevich emission line diagrams. Considering a sample of 115 ram-pressure-stripped galaxies with stellar masses ≥ 10⁹ M _⊙, we find an AGN fraction of ~27%. This fraction strongly depends on stellar mass: it raises to 51% when only ram-pressure-stripped galaxies of masses M _* ≥ 10¹⁰ M _⊙ are considered. We then investigate whether the AGN incidence is in excess in ram-pressure-stripped galaxies compared to nonstripped galaxies using as a comparison a sample of noncluster galaxies observed by the MaNGA survey. Considering mass-matched samples, we find that the incidence of AGN activity is significantly higher (at a confidence level >99.95%) when RPS is in the act, supporting the hypothesis of an AGN-ram pressure connection.