On the accretion of a new group of galaxies on to Virgo: II. The effect of pre-processing on the stellar population content of dEs

Bahar Bidaran, Francesco La Barbera, Anna Pasquali, Reynier Peletier, Glenn van de Ven, Eva K. Grebel, Jesus Falcón-Barroso, Agnieszka Sybilska, Dimitri A. Gadotti, Lodovico Coccato

Using MUSE spectra, we investigate how pre-processing and accretion on to a galaxy cluster affect the integrated stellar population properties of dwarf early-type galaxies (dEs). We analyse a sample of nine dEs with stellar masses of ∼ 109, M, which were accreted (∼2-3 Gyr ago) on to the Virgo cluster as members of a massive galaxy group. We derive their stellar population properties, namely age, metallicity ([M/H]), and the abundance ratio of α elements ([α/Fe]), by fitting observed spectral indices with a robust, iterative procedure, and infer their star formation history (SFH) by means of full spectral fitting. We find that these nine dEs are more metal-poor (at the 2-3σ level) and significantly more α-enhanced than dEs in the Virgo and Coma clusters with similar stellar mass, clustercentric distance, and infall time. Moreover, for six dEs, we find evidence for a recent episode of star formation during or right after the time of accretion on to Virgo. We interpret the high [α/Fe] of our sample of dEs as the result of the previous exposure of these galaxies to an environment hostile to star formation, and/or the putative short burst of star formation they underwent after infall into Virgo. Our results suggest that the stellar population properties of low-mass galaxies may be the result of the combined effect of pre-processing in galaxy groups and environmental processes (such as ram-pressure triggering star formation) acting during the early phases of accretion on to a cluster.

Department of Astrophysics
External organisation(s)
Ruprecht-Karls-Universität Heidelberg, INAF Astronomical Observatory of Capodimonte , University of Groningen, Instituto de Astrofísica de Canarias, Universidad de La Laguna, Sybilla Technologies, European Southern Observatory (Germany), Durham University
Monthly Notices of the Royal Astronomical Society
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103003 Astronomy, 103004 Astrophysics
ASJC Scopus subject areas
Astronomy and Astrophysics, Space and Planetary Science
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