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arXiv · 2207.06977

On the accretion of a new group of galaxies onto 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
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Abstract

Using MUSE spectra, we investigate how pre-processing and accretion onto a galaxy cluster affect the integrated stellar population properties of dwarf early-type galaxies (dEs). We analyze a sample of nine dEs with stellar masses of $\rm \sim 10^9 \, M_\odot$, which were accreted ($\sim$ 2-3 Gyr ago) onto 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 $\alpha$ elements ([$\alpha$/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 2-3$\sigma$ level) and significantly more $\alpha$-enhanced than dEs in the Virgo and Coma clusters with similar stellar mass, cluster-centric 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 onto Virgo. We interpret the high [$\alpha$/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 onto a cluster.

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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. 2022-07-14. On the accretion of a new group of galaxies onto Virgo: II. The effect of pre-processing on the stellar population content of dEs. https://doi.org/10.1093/mnras%2Fstac2005

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