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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

Bidaran, Bahar and La Barbera, Francesco and Pasquali, Anna and Peletier, Reynier and van de Ven, Glenn and Grebel, Eva K and Falcón-Barroso, Jesus and Sybilska, Agnieszka and Gadotti, Dimitri A and Coccato, Lodovico (2022) '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.', Monthly Notices of the Royal Astronomical Society, 515 (3). pp. 4622-4638.


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 ∼109M⊙⁠, 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.

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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2022 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:13 July 2022
Date deposited:22 September 2022
Date of first online publication:22 July 2022
Date first made open access:22 September 2022

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