J/other/Univ/11.392 Radio High-Redshift Quasar Catalog, RHzQCat-I (Zhang+, 2025)
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.
Zhang Y., Lin R., Perger K., Frey S., An T., Ji X., Wu Q., Liao S.
<Universe, 11, 392 (2025)>
=2025Univ...11..392Z 2025Univ...11..392Z (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; Active gal. nuclei ; Redshifts
Keywords: high-redshift galaxies - quasars - supermassive black holes -
observational astronomy
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≳5, the cosmic morning epoch (3≲z≲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
1025.5-1029.3W/Hz. 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≥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).
Description:
This catalog provides the final RHzQCat-I catalog, covering radio AGNs
at redshifts (3, 5.5). It includes spectroscopic redshifts (from SDSS)
and radio detection information of 2388 sources (1629 reliable RHRQs,
315 candidate RHRQs and 78 rejected sources). The two tables are both
for all sources: table1_category presents redshifts and information on
source categories; table2_parameters present source radio flux density
measurements from different radio surveys (i.e. FIRST, NVSS, RACS,
GLEAM).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
category.dat 294 2388 Category information of the sources
param.dat 239 2388 Radio observation from surveys
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See also:
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16, DR16 (Ahumada+, 2020)
VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)
VIII/100 : GaLactic & Extragalactic All-sky MWA survey (Hurley-Walker+, 2016)
J/other/PASA/38.58 : Rapid ASKAP Continuum Survey. II. RACS cat. (Hale+, 2021)
Byte-by-byte Description of file: category.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS Source name from SDSS DR16Q
20- 31 F12.8 deg RAdeg [0.07/359.74] SDSS Right ascension (J2000)
33- 44 F12.8 deg DEdeg [-10.66/68.33] SDSS Declination (J2000)
46- 55 A10 --- Category The final category of the source
(good, candidate, or rejected) (G1)
57- 61 F5.3 --- z [3.0/7.01] Spectroscopic redshift from
DR16Q
63- 71 A9 --- r_z Source of redshift derived from DR16Q
(see original paper)
73- 74 I2 --- f_z [-1/68] Binary flag on SDSS pipeline
redshift estimate quality
(see original paper)
76 I1 --- q_z [1/3] Flag on the reliability of the
targets redshift
78- 81 I4 --- MatchTierCode [3/3330] The four-digit code showing the
tier flags for each radio survey
83- 98 A16 --- FIRST Source name from the FIRST survey catalog
100-112 A13 --- NVSS Source name from the NVSS survey catalog
114-129 A16 --- RACS Source name from the RACS-DR1 survey
catalog
131-144 A14 --- GLEAM Source name from the GLEAM survey catalog
146-151 F6.3 arcsec SepFIRST [0.0/2.58]? The optical-radio separation
from source positions in FIRST and SDSS
153-159 F7.3 arcsec SepNVSS [0.02/24.86]? The optical-radio separation
from source positions in NVSS and SDSS
161-167 F7.3 arcsec SepRACS [0.02/13.91]? The optical-radio separation
from source positions in RACS-DR1
and SDSS
169-176 F8.3 arcsec SepGLEAM [1.17/107.56]? The optical-radio
separation from source positions
in GLEAM and SDSS
178-182 A5 --- VIcodeFIRST Radio identification code on source
morphology and type on FIRST (2)
184-190 A7 --- VIcodeNVSS Radio identification code on source
morphology and type on NVSS (2)
192-197 A6 --- VIcodeRACS Radio identification code on source
morphology and type on RACS-DR1 (2)
199-204 A6 --- VIcodeGLEAM Radio identification code on source
morphology and type on GLEAM (2)
206-241 A36 --- comment1 Comment on the source identification from
visual inspection
243-294 A52 --- comment2 Comment on the source morphology from
visual inspection
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Note (2): Codes as follows:
U = Unresolved, single point-like component
Uaf = Unresolved, single point-like component. Affected, radio emission
affected by nearby sources or lobes (optical quasar is not
centered at the radio source)
Ucp = Unresolved, single point-like component. Counterpart dominated,
radio source is centered on a low-redshift optical counterpart
(optical quasar is not centered at the radio source)
Uoff = Unresolved, single point-like component. Off-centered, radio source
centroid shows a significant offset from the optical quasar
(optical quasar is not centered at the radio source)
SE = Slightly extended, single component with slightly extended
structure
SEaf = Slightly extended, single component with slightly extended
structure. Affected, radio emission affected by nearby sources or
lobes (optical quasar is not centered at the radio source)
SEoff = Slightly extended, single component with slightly extended
structure. Radio source centroid shows a significant offset from
the optical quasar (optical quasar is not centered at the
radio source)
E = Elongated, single elongated profile that is likely distorted by
nearby source flux densities
Eaf = Elongated, single elongated profile that is likely distorted by
nearby source flux densities. Affected, radio emission affected by
nearby sources or lobes (optical quasar is not centered at the
radio source)
Ecp = Elongated, single elongated profile that is likely distorted by
nearby source flux densities. Counterpart dominated, radio source
is centered on a low-redshift optical counterpart (optical quasar
is not centered at the radio source)
Eoff = Elongated, single elongated profile that is likely distorted by
nearby source flux densities. Off-centered, radio source centroid
shows a significant offset from the optical quasar (optical quasar
is not centered at the radio source)
CJ = Core'jet, one circular component with a one-sided tail-like jet
structure
CJaf = Core'jet, one circular component with a one-sided tail-like jet
structure. Affected, radio emission affected by nearby sources or
lobes (optical quasar is not centered at the radio source)
CJcp = Core'jet, one circular component with a one-sided tail-like jet
structure. Counterpart dominated, radio source is centered on a
low-redshift optical counterpart (optical quasar is not centered
at the radio source)
CJoff = Core'jet, one circular component with a one-sided tail-like jet
structure. Off-centered, radio source centroid shows a significant
offset from the optical quasar (optical quasar is not centered at
the radio source)
FRI = Radio galaxy FR I, radio galaxy with FR I-like morphology. Radio
source centroid shows a significant offset from the optical quasar
(optical quasar is not centered at the radio source)
FRII = Radio galaxy FRII, radio galaxy with FR II-like morphology
FRIIaf = Radio galaxy FRII, radio galaxy with FR II-like morphology.
Affected, radio emission affected by nearby sources or lobes
(optical quasar is not centered at the radio source)
FRIIcp = Radio galaxy FRII, radio galaxy with FR II-like morphology.
Counterpart dominated, radio source is centered on a low-redshift
optical counterpart (optical quasar is not centered at the radio
source)
FRIIoff = Radio galaxy FRII, radio galaxy with FR II-like morphology.
Off-centered, radio source centroid shows a significant offset
from the optical quasar (optical quasar is not centered at the
radio source)
OIaf = One-sided FR II, FR II-like radio source with optical core centered
at one of the lobes. Affected, radio emission affected by nearby
sources or lobes (optical quasar is not centered at the radio
source)
OII = One-sided FR II, FR II-like radio source with optical core centered
at one of the lobes
OIIaf = One-sided FR II, FR II-like radio source with optical core centered
at one of the lobes. Affected, radio emission affected by nearby
sources or lobes (optical quasar is not centered at the radio
source)
OIIoff = One-sided FR II, FR II-like radio source with optical core centered
at one of the lobes. Off-centered, radio source centroid shows a
significant offset from the optical quasar (optical quasar is not
centered at the radio source)
M = Multiple components, more than one component located within a
small or continuous region
ND = Not detected, no radio emission detected at the position of the
optical quasar
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Byte-by-byte Description of file: param.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS Source name from SDSS DR16Q
20- 31 F12.8 deg RAdeg [0.07/359.74] SDSS Right ascension
(J2000)
33- 44 F12.8 deg DEdeg [-10.66/68.33] SDSS Declination (J2000)
46- 55 A10 --- Category The final category of the source
(good, candidate, or rejected) (G1)
57- 61 F5.3 --- z [3.0/7.01] Spectroscopic redshift from
DR16Q
63- 78 A16 --- FIRST Source name from the FIRST survey
catalog
80- 87 F8.2 mJy/beam FpeakFirst [0.75/2404.56]? Peak flux density at
1.4GHz from FIRST
89- 96 F8.2 mJy FintFirst [0.46/2430.88]? Integrated flux density
at 1.4GHz from FIRST
98-103 F6.3 mJy/beam rmsFirst [0.08/1.73]? rms noise of the source
at 1.4GHz from FIRST
105-117 A13 --- NVSS Source name from the NVSS survey catalog
119-125 F7.1 mJy S1.4NVSS [2.1/2417.6]? Total flux density
at 1.4GHz from NVSS
127-131 F5.1 mJy e_S1.4NVSS [0.4/72.5]? Uncertainty of source flux
density at 1.4GHz from NVSS
133-148 A16 --- RACS-DR1 Source name from the RACS-DR1 survey
catalog
150-158 F9.3 mJy/beam FpkRACS [1.18/1010.34]? Peak flux density
from RACS-DR1
160-165 F6.3 mJy/beam e_FpkRACS [0.2/4.76]? Uncertainty of peak flux
density from RACS-DR1
167-175 F9.3 mJy FtotRACS [1.22/1038.48]? Total flux density
from RACS-DR1
177-182 F6.3 mJy e_FtotRACS [0.36/8.22]? Uncertainty of total flux
density from RACS-DR1
184-197 A14 --- GLEAM Source name from the GLEAM survey
catalog
199-207 F9.6 Jy/beam FpwideGLEAM [0.04/7.01]? Peak intensity of the GLEAM
source in the wide-band image
209-217 F9.6 Jy/beam e_FpwideGLEAM [0.0/0.09]? Uncertainty of peak
intensity of the GLEAM source in the
wide-band image
219-227 F9.6 Jy FintwideGLEAM [0.04/6.76]? Integrated intensity of the
GLEAM source in the wide-band image
229-239 F11.8 Jy e_FintwideGLEAM [0.0/0.2]? Uncertainty of
integrated intensity of the GLEAM
source in the wide-band image
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Global notes:
Note (G1): Categories as follows:
good = good, Sources with both trustworthy redshifts and a consistent
radio morphology identified as good during the inspection
good B = good, Sources with both trustworthy redshifts and a consistent
radio morphology identified as good during the inspection
cand A = candidate, sources with uncertain redshifts
(zreliableflag = 2) but visually classified as good
cand B = candidate, sources with reliable redshifts but visually
classified as candidate
cand C = candidate, sources with inconsistencies in both verifications
rejected A = rejected, sources discarded based on unreliable redshifts
without visual inspection
rejected B = rejected, sources rejected during the visual inspection
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Acknowledgements:
Yingkang Zhang, ykzhang(at)shao.ac.cn
(End) Patricia Vannier [CDS] 08-Jan-2026