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 use data from the GAMA and GALEX surveys to demonstrate that the UVupturn, an unexpected excess of ultraviolet flux from a hot stellar component,seen in the spectra of many early-type galaxies, arises from processes internalto individual galaxies with no measurable influence from the galaxies' largerenvironment. We first define a clean sample of passive galaxies without asignificant contribution to their UV flux from low-level star formation. Weconfirm that galaxies with the optical colours of red sequence galaxies oftenhave signs of residual star formation, which, without other information, wouldprevent a convincing demonstration of the presence of UV upturns. However, byincluding (NUV$-u$) and {\it WISE} (W2-W3) colours, and FUV data where itexists, we can convincingly constrain samples to be composed ofnon-star-forming objects. Using such a sample, we examine GALEX photometry oflow redshift GAMA galaxies in a range of low-density environments, from groupsto the general field, searching for UV upturns. We find a wide range of(NUV$-r$) colours, entirely consistent with the range seen -- and attributed tothe UV upturn -- in low-redshift red sequence cluster galaxies. The range ofcolours is independent of group multiplicity or velocity dispersion, withisolated passive galaxies just as likely to have blue UV-to-optical colours,implying significant upturn components, as those in richer groups and in theprevious data on clusters. This is supported by equivalent results for(FUV$-r$) colours which are clear indicators of upturn components.

Galaxy And Mass Assembly (GAMA): Defining Passive Galaxy Samples and Searching for the UV Upturn