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Title: The NUV–r versus M{sub r} plane as a tracer of early-type galaxy evolution in the USGC U376 and LGG 225 groups

With the aim of tracing back the evolution of galaxies in nearby groups, we use smooth particle hydrodynamical (SPH) simulations with chemo-photometric implementation. Here, we focus on the evolution of the early-type members (Es and S0s; ETGs hereafter) in two groups, USGC U376 and LGG 225, both in the Leo cloud. We use the near-UV (NUV)-optical rest-frame NUV–r versus M{sub r} color-magnitude diagram to follow their evolution, from the blue cloud (BC) to the red sequence (RS), through the green valley (GV). ETGs brighter than M{sub r} = –21 mag are older than 13 Gyr and spend up to 10 Gyr of their overall evolutionary time in the BC before they reach the RS, migrating through the GV. Fainter ETGs are younger, ≈2 Gyr on average, and evolve for about 7-8 Gyr along the BC. The turn-off occurs at z ≈ 0.3-0.4. Therefore, these ETGs spend up to 3-5 Gyr crossing the GV; UGC 06324, the faintest ETG in the sample, still is in the GV. The mechanism driving their evolution is gravitational, due to merging and/or interaction. Our SPH simulations suggest that ETG members of these groups evolved toward the RS before and during the group collapse phase. Thismore » result is consistent with the dynamical analysis of both groups showing that they are not yet virialized.« less
Authors:
;  [1] ;  [2]
  1. INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio, 5, I-35122 Padova (Italy)
  2. Università di Padova, Dipartimento di Fisica e Astronomia G. Galilei, Vicolo dell'Osservatorio, 3, I-35122 Padova (Italy)
Publication Date:
OSTI Identifier:
22348025
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COLOR; EVOLUTION; GALAXIES; INTERACTIONS; PARTICLES; SIMULATION