Investigating Early-type Galaxy Evolution with a Multiwavelength Approach. III. Insights from SPH Simulations with Chemophotometric Implementation

Abstract

We are exploring galaxy evolution in low density environments exploiting smooth particle hydrodynamic simulations including chemo-photometric implementation. From a large grid of simulations of galaxy encounters and mergers starting from triaxial halos of gas e dark matter, we single out the simulations matching the global properties of our targets. These simulations are used to give insights into their evolution. We focus on 11 early-type galaxies selected because of their nearly passive stage of evolution in the nuclear region. However, a variety of UV features are detected in more than half of these galaxies. We find no significant differences in the formation mechanisms between galaxies with or without UV features. Major and minor mergers are able to reproduce their peculiar UV morphologies, galaxy encounters are more suitable for 'normal' early-type galaxies. Their star formation rate self-quenches several Gyr later the merger/encounter occurred, via gas exhaustion and stellar feedback, moving the galaxy from blue to red colors, driving the galaxy transformation. The length of the quenching is mass dependent and lasts from 1 to 5 Gyr or more in the less massive systems. All our targets are gas rich at redshift 1. Three of them assembled at most 40% of their current stellar mass at z>1, and seven assembled more than 50% between redshift 0.5 and 1. Their stellar mass grows with 4% by crossing the Green Valley before reaching their current position on the NUV−r vs. M r diagram.

Dorado and its member galaxies

“…Mergers can transform LTGs into ETGs, that is both S0s and ellipticals (see e.g. Toomre & Toomre 1972;Barnes 2002;Mazzei et al 2014aMazzei et al , 2019 and quench star formation (SF) by ejecting the interstellar medium via starburst-, AGN-, or shock-driven winds (see e.g. Di Matteo 2015, and references therein).…”

Dorado and its member galaxies II: A UVIT picture of the NGC 1533 substructure

“…6.1 FUV and evolution of member galaxies Mazzei et al (2014aMazzei et al ( , 2019 and references therein, using smoothed particle hydrodynamic simulations with chemo-photometric implementation (SPH-CPI), investigated the evolutionary path of NGC 1533, the dominant member of the sub-structure.…”

“…We plan to further explore the comparison of SFR from Ha and FUV using the entire UVIT data-set of the Dorado backbone, considering extinction effects in more detail than in Lee et al (2009) assumptions (Rampazzo et al in preparation). The SPH chemophotometric simulation of NGC 1533 by Mazzei et al (2019) provided an estimate of the internal galaxy extinction. We will use also such estimates.…”

High‐resolution morphology and surface photometry of KIG 685 and KIG 895 with ARGOS+LUCI using the Large Binocular Telescope

“…Structures such as shells and ripples in ellipticals (Malin & Carter ) have long been associated with either minor or major mergers (Dupraz & Combes , ; Weil & Hernquist ). Recently, Eliche‐Moral et al () and Mazzei et al () show that some features in S0s, such as arm‐like structures and rings, may be generated by mergers. In general, it is more common to detect merger relics in S0s that formed via minor mergers than major mergers in a given evolutionary period.…”

“…Such results are corroborated by mid‐infrared nuclear spectroscopy performed by Spitzer ‐IRS, which detected polycyclic aromatic hydrocarbons (Panuzzo et al ; Rampazzo et al ; Vega et al ), that is, signatures of recent star formation activity. A fair upper limit to the contribution of rejuvenation episodes in the last 2 Gyr is ∼25% of the total galaxy stellar mass (Annibali et al ), but episodes are typically much less intense than that (few percentages, e.g., Mazzei et al ; Panuzzo et al ; Rampazzo et al ).…”