The FIRST radio survey: The K-z diagram of FIRST radio sources identified in the Bo\"{o}tes and Cetus fields

TL;DR

This study establishes a linear K-z relation for FIRST radio sources, revealing that their optical brightness correlates with redshift and radio power, and compares these sources with other radio samples to understand galaxy evolution.

Contribution

It provides the first detailed K-z diagram for FIRST radio sources, highlighting their luminosity evolution and relation to radio power across different flux limits.

Findings

The K-z relation for FIRST sources is linear with low dispersion at high redshift.

Most FIRST sources are fainter than no-evolution galaxy models, indicating luminosity evolution.

Radio luminosity correlates with galaxy brightness and evolution.

Abstract

This paper presents the Hubble diagram (K-z relation) for FIRST (Faint Images of the Radio Sky at 20 cm) radio sources identified in the Bootes and Cetus fields. The correlation between the K magnitude of the FIRST-NDWFS sample and the photometric redshifts found to be linear. The dispersion about the best fit line is given by 1.53 for the whole sample and 0.75 at z>1. The paper also presents a composite K-z diagram of FIRST radio sources and low-frequency selected radio samples with progressively fainter flux-density limits (3CRR, 6C, 7CRS and the EIS-NVSS sample). The majority of FIRST radio sources lie fainter than the no evolution curve (3L* galaxies) probably highlighting the fact that the galaxy luminosity is correlated with the radio power.