J/A+A/695/A69 Associated clusters of RGs and quasars (Pan+, 2025)
The environments of radio galaxies and quasars in LoTSS data release 2.
Pan T., Fu Y., Rottgering H.J.A., van Weeren R.J., Drake A.B., Yue B.H.,
Petley J.W.
<Astron. Astrophys. 695, A69 (2025)>
=2025A&A...695A..69P 2025A&A...695A..69P (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Active gal. nuclei ; QSOs ; Galaxies, radio
Keywords: galaxies: active - galaxies: clusters: general - quasars: general -
radio continuum: galaxies
Abstract:
The orientation-based unification scheme of radio-loud active galactic
nuclei (AGNs) asserts that radio galaxies and quasars are essentially
the same type of object, but viewed from different angles. To test
this unification model, we compared the environments of radio galaxies
and quasars, which would reveal similar properties when an accurate
model is utilized.
Using the second data release of the LOFAR Two-metre Sky Survey (LoTSS
DR2), we constructed a sample of 26577 radio galaxies and 2028 quasars
at 0.08<z<0.4. For radio galaxies with optical spectra, we further
classified them as 3631 low-excitation radio galaxies (LERGs) and 1143
high-excitation radio galaxies (HERGs). We crossmatched these samples
with two galaxy cluster catalogs from the Sloan Digital Sky Survey
(SDSS).
We find that 17.1±0.2% of the radio galaxies and 4.1±0.4% of
the quasars are associated with galaxy clusters. Luminous quasars are
very rare in clusters, while 18.7±0.7% LERGs and 15.2±1.1% HERGs
reside in clusters. We also note that in radio galaxies, both HERGs
and LERGs tend to reside in the centers of clusters, while quasars do
not show a strong preference for their positions in clusters.
This study shows that local quasars and radio galaxies exist in
different environments, challenging the orientation-based unification
model. This means that factors other than orientation may play an
important role in distinguishing radio galaxies from quasars. The
future WEAVE-LOFAR survey will offer high-quality spectroscopic data
for a large number of radio sources and allow for a more comprehensive
exploration of the environments of radio galaxies and quasars.
Description:
Using the LoTSS DR2, we constructed a sample of radio galaxies
and quasars within the redshift range 0.08<z<0.4. We find that 4552
(17.1±0.2%) radio galaxies and 84 (4.1±0.4%) quasars are
associated with galaxy clusters. The cluster match fractions of radio
galaxies and quasars differ, indicating that they reside in distinct
environments.
This catalog contains information on 84 quasars/4552 radio
galaxies located within clusters, along with details about the
clusters associated with these quasars/radio galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
qw2mpc.dat 109 84 Quasars and their associated clusters
rgw2mpc.dat 111 4552 Radio galaxies and their associated clusters
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See also:
J/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)
Byte-by-byte Description of file: qw2mpc.dat rgw2mpc.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Index [0/4551] Sequential number
6- 13 F8.4 deg RAdeg Right Ascension (J2000) of the source
15- 20 F6.3 deg DEdeg Declination (J2000) of the source
22- 26 F5.3 --- z redshift
28- 45 F18.15 [W/Hz] logL150MHz Logarithm of 150MHz radio luminosity
47- 62 A16 --- Cluster Name of associated clusters,
JHHMMSS.s+DDMMSS
64- 71 F8.4 deg RAcdeg Right Ascension (J2000) of the
associated cluster
73- 80 F8.5 deg DEcdeg Declination (J2000) of the
associated cluster
82- 87 F6.2 --- Richness Cluster richness
89-111 E23.18 Mpc Dproj Projected distance from source to cluster
centre
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Acknowledgements:
Tong Pan, tpan(at)strw.leidenuniv.nl
(End) Tong Pan [Univ. Leiden], Patricia Vannier [CDS] 25-Feb-2025