English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present the results of a study of stellar population properties at large galactocentric radii of 14 low‐mass early‐type galaxies in the Fornax and Virgo clusters. We derive radial profiles of age, total metallicity [Z/H] and [α/Fe] abundance ratios out to ∼1–3 effective radii by using nearly all of the Lick/IDS absorption‐line indices in comparison to recent single stellar population models. We extend our study to higher galaxy mass via a novel literature compilation of 37 early‐type galaxies, which provides stellar population properties out to one effective radius. We find that metallicity gradients correlate with galactic mass, and the relationship shows a sharp change in slope at a dynamical mass of  ∼3.5 × 10 10  M ⊙  . The central and mean values of the stellar population parameters (measured in   r ≤ r  e /8  and at   r = r  e  , respectively) define positive mass trends. We suggest that the low metallicities, almost solar [α/Fe] ratios and the tight mass–metallicity gradient relation displayed by the low‐mass galaxies are indicative of an early star‐forming collapse with extended (i.e. ≥1 Gyr), low‐efficiency star formation, and mass‐dependent galactic outflows of metal‐enriched gas. The flattening of metallicity gradients in high‐mass galaxies and the broad scatter of the relationship are attributed to merger events. The high metallicities and supersolar abundances shown by these galaxies imply a rapid, high efficiency star formation. The observed [Z/H]–mass and [α/Fe]–mass relationships can be interpreted as a natural outcome of an early star‐forming collapse. However, we find that hierarchical galaxy formation models implementing mass‐dependent star formation efficiency, varying initial mass function, energy feedback via active galactic nucleus and the effects due to merger‐induced starbursts can also reproduce both our observed relationships.

Early‐type galaxies at large galactocentric radii – II. Metallicity gradients and the [Z/H]–mass, [α/Fe]–mass relations