Building a Radio AGN Sample from Cosmic Morning -- The Radio High-Redshift Quasar Catalog (RHzQCat): I. Catalog from SDSS Quasars and Radio Surveys at $z>3$

Abstract

Radio-loud high-redshift quasars (RHRQs) provide crucial insights into the evolution of relativistic jets and their connection to the growth of supermassive black holes. Beyond the extensively studied population at $z\ge 5$, the cosmic morning epoch ($3\lesssim z\lesssim 5$) marks the peak of active galactic nucleus (AGN) activity and black hole accretion, yet remains relatively unexplored. In this work, we compiled the radio high-redshift quasar catalog (RHzQCat) by cross-matching the SDSS DR16Q catalog with four major radio surveys -- FIRST,NVSS, RACS, and GLEAM. Our tier-based cross-matching framework and visual validation ensured reliable source identification across surveys with diverse beam sizes. The catalog included 1629 reliable and 315 candidate RHRQs, with radio luminosities uniformly spanning $10^{25.5}$ -- $10^{29.3}$ W Hz${}^{-1}$. About 95\% of the confirmed sources exhibited compact morphologies, consistent with Doppler-boosted or young AGN populations at high redshifts. Our catalog increases the number of known RHRQs at $z\ge 3$ by an order of magnitude, representing the largest and most homogeneous catalog of radio quasars at cosmic morning, filling the observational gap between the early ($z>6$) and local Universe. It provides a robust reference for future statistical studies of jet evolution, AGN feedback, and cosmic magnetism with next-generation facilities such as the Square Kilometer Array (SKA).

26 pages, 9 figures, published by Universe as part of Special Issue: Advances in Studies of Galaxies at High Redshift. Issue website: https://www.mdpi.com/2218-1997/11/12/392 paper link: https://www.mdpi.com/2218-1997/11/12/392/pdf Supplementary data can be found via zenodo: https://doi.org/10.5281/zenodo.17667135

References in corpus (27)

• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release
• Compact steep-spectrum and peaked-spectrum radio sources
• The faint radio sky: radio astronomy becomes mainstream
• The Rapid ASKAP Continuum Survey Paper II: First Stokes I Source Catalogue Data Release
• Radio Loud and Radio Quiet Quasars
• Radio-Selected Binary Active Galactic Nuclei from the Very Large Array Stripe 82 Survey
• On the Accretion Rates and Radiative Efficiencies of the Highest Redshift Quasars
• Blazar candidates beyond redshift 4 observed by Swift
• The first estimate of radio jet proper motion at z>5
• Evolving parsec-scale radio structure in the most distant blazar known
• Parsec-scale properties of the radio brightest jetted AGN at z > 6
• Blazars at the Cosmic Dawn
• DESI z >~ 5 Quasar Survey. I. A First Sample of 400 New Quasars at z ~ 4.7-6.6
• Do high redshift quasars have powerful jets?
• Status and progress of China SKA Regional Centre prototype
• High-redshift quasars at $z\ge 3$ -- I. Radio spectra
• Radio-loud Quasars above Redshift 4: VLBI Imaging of an Extended Sample
• Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). III. Discovery of a z = 4.72 Radio Galaxy with Lyman Break Technique
• Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5
• The GLEAMing of the First Supermassive Black Holes
• Radio-loud fraction of z>6 quasars
• Optical and near-infrared spectroscopy of quasars at $z>6.5$: public data release and composite spectrum
• Radio-loudness statistics of quasars from Quaia-VLASS
• High-$z$ radio Quasars in RACS I: Selection, identification, and multi-wavelength properties
• Revisiting a Core-Jet Laboratory at High Redshift: Analysis of the Radio Jet in the Quasar PKS 2215+020 at z=3.572
• Superluminal Motion and Jet Parameters in the High-Redshift Blazar J1429+5406