Evidence for the rapid formation of low-mass early-type galaxies in dense environments

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DOIResolve DOI: http://doi.org/10.3847/0004-637X/818/2/179
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TypeArticle
Journal titleThe Astrophysical Journal
ISSN1538-4357
Volume818
Issue2
Article number179
SubjectGalaxy abundances; Cluster galaxies; Individual galaxies; Virgo; Dwarf galaxies; Galaxy formation; Star cluster galaxies
AbstractWe explore the environmental dependence of star formation timescales in low-mass galaxies using the [α/Fe] abundance ratio as an evolutionary clock. We present integrated [α/Fe] measurements for 11 low-mass (M*∼10⁹M⊙) early-type galaxies (ETGs) with a large range of cluster-centric distance in the Virgo Cluster. We find a gradient in [α/Fe], where the galaxies closest to the cluster center (the cD galaxy, M87) have the highest values. This trend is driven by galaxies within a projected radius of 0.4 Mpc (0.26 times the virial radius of Virgo A), all of which have super-solar [α/Fe]. Galaxies in this mass range exhibit a large scatter in the [α/Fe]–σ diagram, and do not obviously lie on an extension of the relation defined by massive ETGs. In addition, we find a correlation between [α/Fe] and globular cluster specific frequency (SN), suggesting that low-mass ETGs that formed their stars over a short period of time were also efficient at forming massive star clusters. The innermost low-mass ETGs in our sample have [α/Fe] values comparable to that of M87, implying that environment is the controlling factor for star formation timescales in dense regions. These low-mass galaxies could be the surviving counterparts of the objects that have already been accreted into the halo of M87, and may be the link between present-day low-mass galaxies and the old, metal-poor, high-[α/Fe], high-SN stellar populations seen in the outer halos of massive ETGs.
Publication date
PublisherIOP Publishing
LanguageEnglish
AffiliationNational Science Infrastructure; National Research Council Canada
Peer reviewedYes
NPARC number23000045
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Record identifier946df784-cb3d-472b-acdb-bb155fd49f88
Record created2016-05-31
Record modified2016-05-31
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