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

[Abridged] The nature and evolutionary properties of the faint radiopopulation, responsible for the steepening observed in the 1.4 GHz sourcecounts below 1 milliJy, are not yet entirely clear. Radio spectral indices mayhelp to constrain the origin of the radio emission in such faint radio sourcesand may be fundamental in understanding eventual links to the optical light. Westudy the spectral index behaviour of sources that were found in the 1.4 GHzATESP survey (Prandoni et al. 2000a,b). Using the Australia Telescope CompactArray we observed at 5 GHz part of the region covered by the sub-mJy ATESPsurvey. In particular we imaged a one square degree area for which deep opticalimaging in UBVRIJK is available. In this paper we present the 5 GHz survey andsource catalogue, we derive the 5 GHz source counts and we discuss the 1.4-5GHz spectral index properties of the ATESP sources. The analysis of the opticalproperties of the sample will be the subject of a following paper. The 5 GHzsurvey has produced a catalogue of 111 radio sources, complete down to a (6sigma) limit S_lim(5 GHz)~0.4 mJy. We take advantage of the better spatialresolution at 5 GHz (~2 arcsec compared to ~8 arcsec at 1.4 GHz) to infer radiosource structures and sizes. The 5 GHz source counts derived by the presentsample are consistent with those reported in the literature, but improvesignificantly the statistics in the flux range 0.4< S(5 GHz)<1 mJy. The ATESPsources show a flattening of the 1.4-5 GHz spectral index with decreasing fluxdensity, which is particularly significant for the 5 GHz selected sample. Sucha flattening confirm previous results coming from smaller samples and isconsistent with a flattening of the 5 GHz source counts occurring at fluxes<=0.5 mJy.Comment: 22 pages, 13 figures Accepted for publication on Astronomy and  Astrophysics. Replaced version: corrected typos and references update

The ATESP 5 GHz radio survey