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 report the discovery of a radio loud quasar with a redshift of 4.30. Thisobject, which is the first radio selected quasar with a redshift greater thanfour, was discovered during an observational investigation into the evolutionof the luminosity function of radio loud quasars. Here we describe resultsbased on a sample of ~300, flat spectrum radio sources with S(5GHz) > 200mJy.In this study, rather than carry out an indiscriminate redshift campaign on allthe radio sources, we have used the APM POSS catalogue to preselect a subset ofstellar-like optical counterparts with red optical colours. Such a subsample isexpected to contain a high fraction of high redshift quasars. 10 of the ~300sources were selected for follow-up optical spectroscopy and three of these areidentified as quasars with redshifts greater than 3.0. One of the radiosources, GB1508+5714, is a quasar with z=4.30 and m(R)~19.Comment: 5 pages, one uuencoded compressed postscipt file (created with  uufiles) including figures. MNRAS Letter, in press

GB:1508+5714: a radio-loud quasar with z = 4.30 and the space density of high-redshift radio-loud quasars