Midlife Crises in Dwarf Galaxies in the NGC 5353/4 Group

TL;DR

This study examines the properties and evolution of dwarf galaxies in the NGC 5353/4 Group, highlighting their concentration, star formation activity, and the group's dynamical state, suggesting ongoing infall and a less evolved system.

Contribution

It provides detailed analysis of dwarf galaxy distribution, star formation, and group dynamics in the NGC 5353/4 Group, a less studied intermediate-mass galaxy group.

Findings

Dwarf galaxies are concentrated toward the group core.

The mass-to-light ratio is lower than in earlier studied groups.

Evidence of ongoing group collapse and star formation activity.

Abstract

This third paper in a series about the dwarf galaxy populations in groups within the Local Supercluster concerns the intermediate mass (2.1 x 10^13 solar) NGC 5353/4 Group with a core dominated by S0 systems and a periphery of mostly spiral systems. Dwarf galaxies are strongly concentrated toward the core. The mass to light ratio M/L_R=105 in solar units is a factor 3 lower than for the two groups studied earlier in the series. The properties of the group suggest it is much less dynamically evolved than those two groups of early type galaxies. By comparison, the NGC 5353/4 Group lacks superluminous systems but has a large fraction of intermediate luminosity galaxies; or equivalently, a luminosity function with a flatter faint end slope. The luminosity function for the NGC 5353/4 Group should steepen as the intermediate luminosity galaxies merge. Evidence for the ongoing collapse of the group is provided by the unusually large incidence of star formation activity in small galaxies with early morphological types. The pattern in the distribution of galaxies with activity suggests a succession of infall events. Residual gas in dwarfs that enter the group is used up in sputtering events. The resolution of midlife crises is exhaustion.