The $-12$ mag dip in the galaxy luminosity function of Hickson Compact Groups

TL;DR

This study reveals a characteristic dip at $M_g\, extasciitilde -12$ in the galaxy luminosity functions of Hickson Compact Groups, suggesting galaxy interactions influence galaxy evolution and differentiate galaxy populations.

Contribution

First detection of a $-12$ mag dip in the luminosity functions of Hickson Compact Groups using Subaru data, linking galaxy interactions to LF features.

Findings

Dip at $M_g\, extasciitilde -12$ observed in compact groups and some clusters.

No such dip in Virgo, Hydra, and field galaxy LFs.

Galaxy interactions likely influence galaxy evolution and LF shape.

Abstract

We present the galaxy luminosity functions (LFs) of four Hickson Compact Groups using image data from the Subaru Hyper Suprime-Cam. A distinct dip appeared in the faint-ends of all the LFs at $M_g\sim-12$. A similar dip was observed in the LFs of the galaxy clusters Coma and Centaurus. However, LFs in the Virgo, Hydra, and the field had flatter slopes and no dips. As the relative velocities among galaxies are lower in compact groups than in clusters, the effect of galaxy-galaxy interactions would be more significant in compact groups. The $M_g\sim-12$ dip of compact groups may imply that frequent galaxy-galaxy interactions would affect the evolution of galaxies, and the dip in LF could become a boundary between different galaxy populations.