From starburst to quenching: merger-driven evolution of the star formation regimes in a shell galaxy

ABSTRACT Shell galaxies make a class of tidally distorted galaxies, characterized by wide concentric arc(s), extending out to large galactocentric distances with sharp outer edges. Recent observations young massive star clusters in the prominent shell NGC 474 suggest that such systems host extreme conditions formation. In this paper, we present hydrodynamic simulation galaxy merger and its transformation into galaxy. We analyse how formation activity evolves time, location-wise within system, what are physical for During interaction, an excess dense gas appears, triggering starburst, i.e. enhanced rate reduced depletion time. Star coincides regions high-molecular fraction, as galactic nucleus, spiral arms, occasionally tidal debris during early stages merger. Tidal interactions scatter stars stellar spheroid, while cools down reforms disc. The morphological after coalescence stabilizes thus quenches formation, without need feedback from active nucleus. This evolution shows similarities compaction scenario compact quenched spheroids at high-redshift, yet long red nugget phase. Shells appear coalescence, phase, implying they do not necessary situ results shell-forming mergers might be part process turning blue late-type dead early-types.