Catching Spiral - S0 transition in groups. Insights from SPH simulations with chemo-photometric implementation

TL;DR

This study uses SPH simulations with chemo-photometric data to explore how major mergers influence the evolution of S0 galaxies in groups, including their star formation, kinematics, and transition through the green valley.

Contribution

It demonstrates that major mergers can explain the observed properties and evolutionary paths of S0 galaxies, providing a comprehensive simulation approach.

Findings

Simulations match observed SEDs, brightness profiles, and kinematics of NGC 1533 and NGC 3626.

Residual star formation in S0s can result from major mergers, indicating a rejuvenation phase.

S0 galaxies transition through the green valley in 3-5 Gyr before reaching the red sequence.

Abstract

We are investigating the co-evolution of galaxies within groups combining multi-wavelength photometric and 2D kinematical observations. Here we focus on S0s showing star formation in ring/arm-like structures. We use smooth particle hydrodynamical simulations (SPH) with chemo-photometric implementation which provide dynamical and morphological information together with the spectral energy distribution (SED) at each evolutionary stage. As test cases, we simulate the evolution of two such S0s: NGC 1533 and NGC 3626. The merging of two halos with mass ratio 2:1, initially just composed of dark matter (DM) and gas, well match their observed SEDs, their surface brightness profiles and their overall kinematics. The residual star formation today "rejuvenating" the ring/arm like structures in these S0s is then a mere consequence of a major merger, i.e. this is a phase during the merger episode. The peculiar kinematical features, e.g. gas-stars counter rotation in NGC 3626, depends on the halos initial impact parameters. Furthermore, our simulations allow to follow, in a fully consistent way, the transition of these S0s through the green valley in the NUV-r vs. Mr colour magnitude diagram, which they cross in about 3-5 Gyr, before reaching their current position in the red sequence. We conclude that a viable mechanism driving the evolution of S0s in groups is of gravitational origin.