J/A+A/696/A97 Giant double-double radio galaxies from LoTSS DR2 (Dabhade+, 2025)
Search and analysis of giant radio galaxies with associated nuclei (SAGAN).
V. Study of giant double-double radio galaxies from LoTSS DR2.
Dabhade P., Chavan K., Saikia D.J., Oei M.S.S.L., Rottgering H.J.A.
<Astron. Astrophys. 696, A97 (2025)>
=2025A&A...696A..97D 2025A&A...696A..97D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, radio
Keywords: galaxies: active - galaxies: clusters: general - galaxies: jets -
radio continuum: galaxies
Abstract:
To test the hypothesis that megaparsec-scale giant radio galaxies
(GRGs) experience multiple epochs of recurrent activity leading to
their giant sizes and to understand the nature of double-double radio
galaxies (DDRGs), we have built the largest sample of giant DDRGs from
the LOFAR Two Metre Sky Survey (LoTSS) data release 2. This sample
comprises 111 sources, including 76 newly identified DDRGs, with
redshifts ranging from 0.06 to 1.6 and projected sizes between 0.7Mpc
and 3.3Mpc. We conducted a detailed analysis to characterise their
properties, including arm-length ratios, flux density ratios of pairs
of lobes, and misalignment angles. These measurements allow us to
study the symmetry parameters, which are influenced by the immediate
and large-scale environments of DDRGs. Our study shows that based on
the observed asymmetries of the inner lobes, the cocoons in which the
inner lobes of DDRGs grow are often (approximately about 26%)
asymmetrically contaminated with surrounding material from the
external medium. Our analysis also reveals highly misaligned DDRGs,
which could be due to environmental factors and/or changes in the
supermassive black hole jet ejection axes. By studying the
misalignment angles, we assess the stability of the jets in these
systems in relation to their environment. For the first time, we
systematically characterised the large-scale environments of DDRGs,
identifying their association with dense galaxy clusters and revealing
the influence of "cluster weather" on their morphologies. We have
discovered a DDRG in a distant galaxy cluster at z∼1.4. Our
findings empirically confirm that dynamic cluster environments can
induce significant misalignment in DDRGs, which aligns with previous
simulation predictions and offers insights into how cluster weather
shapes their morphology. Additionally, we have identified two
gigahertz peaked-spectrum (GPS) candidates in the unresolved cores of
the DDRGs, as well as one triple-double candidate, which, if
confirmed, would be only the fifth known case. Overall, this study
enhances our understanding of the life cycle of radio AGNs and
underscores the critical role of the environment in shaping the
properties and evolution of giant DDRGs.
Description:
Using data from the LoTSS DR2 survey, supplemented with ancillary data
from other radio and optical surveys, we have compiled a sample of 111
giant or megaparsec-scale DDRGs, with 76 of these being newly reported
as double-double radio galaxies (DDRGs).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 104 111 Properties of 76 newly identified G-DDRGs (upper)
and 35 known G-DDRGs (lower) within the
LoTSS DR2 sky area
tablea2.dat 133 112 Flux densities, flux density ratios and spectral
indices for our sample of G-DDRGs
tablea3.dat 131 15 Positions, redshifts, magnitudes, cluster
properties, and references for G-DDRGs
hosted by BCGs
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See also:
J/ApJ/736/21 : Galaxy clusters optical catalog from AMF on SDSS DR6
(Szabo+ 2011)
J/ApJ/807/178 : Newly rich galaxy clusters identified in SDSS-DR12
(Wen+, 2015)
J/MNRAS/475/343 : 2MASS, WISE, and SuperCOSMOS clusters of galaxies
(Wen+, 2018)
J/MNRAS/500/1003 : Redshifts for galaxies in the HSC-SSP and unWISE
(Wen+, 2021)
J/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)
J/A+A/642/A153 : SAGAN. I. New sample + multi-wavelength studies
(Dabhade+, 2020)
J/A+A/660/A59 : SAGAN III. New insights into giant radio quasars
(Mahato+, 2022)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- SrNo Sequential number (within the sample)
3 A1 --- n_SrNo Parent sample (G1)
5- 26 A22 --- ILT ILT name (ILTJHHMMSS.ss+DDMMSS.s) of the
sources from the main LoTSS catalogue of
Shimwell et al. (2022A&A...659A...1S 2022A&A...659A...1S,
Cat. J/A+A/659/A1)
28- 29 I2 h RAh Right ascension (J2000) of the
host galaxy (1)
31- 32 I2 min RAm Right ascension (J2000) of the
host galaxy (1)
34- 38 D5.2 s RAs Right ascension (J2000) of the
host galaxy (1)
40 A1 --- DE- Declination sign (J2000) of the
host galaxy (1)
41- 42 I2 deg DEd Declination (J2000) of the host galaxy (1)
44- 45 I2 arcmin DEm Declination (J2000) of the host galaxy (1)
47- 51 F5.2 arcsec DEs Declination (J2000) of the host galaxy (1)
53- 58 F6.4 --- z Redshift
59 A1 --- n_z [+] Note on z (2)
61- 63 I3 arcsec/kpc Outersize Angular size for outer lobe
65- 68 I4 kpc OutersizeP Projected size for outer lobe
70- 72 I3 arcsec/kpc Innersize Angular size for inner lobe
74- 77 I4 kpc InnersizeP Projected size for inner lobe
79- 82 F4.1 deg MAO Misalignment angle between outer lobe
with core
84- 87 F4.1 deg MAI Misalignment angle between inner lobe
with core
89- 92 F4.1 deg MAO-I Misalignment angle between outer lobe
with inner lobe
94- 96 F3.1 --- Rtheta(o) Arm length ratios for outer lobe
98-100 F3.1 --- Rtheta(in) Arm length ratios for inner lobe
102-104 A3 --- Dir Direction of components in which ratios are
taken (3)
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Note (1): Right Ascension and Declination of the host galaxies of the DDRGs
identified from one of the three surveys: SDSS, Pan-STARRS, or
DESI Legacy Imaging Surveys.
Note (2): + represents spectroscopic measurements.
Note (3): We have taken the ratio of measured parameters for farther lobes to
closer lobes from the host for the inner double. The same sense of direction
is used for all the symmetry parameters as given in.
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- SrNo Sequential number (within the sample)
3 A1 --- n_SrNo Parent sample (G1)
5- 26 A22 --- ILT ILT name (ILTJHHMMSS.ss+DDMMSS.s) of the
sources from the main LoTSS catalogue of
Shimwell et al. (2022A&A...659A...1S 2022A&A...659A...1S,
Cat. J/A+A/659/A1)
28- 30 F3.1 --- RS(o) ?=- Flux density ratios for outer lobe
32- 34 F3.1 --- RS(in) ?=- Flux density ratios for inner lobe
36- 38 A3 --- Dir Direction of components in which ratios
are taken
40- 44 F5.1 mJy S144(Outer) ?=- Integrated flux density a 144MHz for
outer lobe (1)
46- 49 F4.1 mJy e_S144(Outer) ? Integrated flux density a 144MHz for
outer lobe error
51- 55 F5.1 mJy S144(Inner) ?=- Integrated flux density a 144MHz for
inner lobe (1)
57- 60 F4.1 mJy e_S144(Inner) ? Integrated flux density a 144MHz for
inner lobe error
62- 66 F5.1 mJy S144(core) ?=- Core flux density from LoTSS
(144MHz) (1)
68- 70 F3.1 mJy e_S144(core) ? Core flux density from LoTSS (144MHz)
error
72- 76 F5.1 mJy S1400(core) ?=- Core flux density from FIRST
(1400MHz) (1)
78- 80 F3.1 mJy e_S1400(core) ? Core flux density from FIRST (1400MHz)
error
81 A1 --- n_S1400(core) [X] Note on S1400(core) (2)
83- 87 F5.1 mJy S3000(core) ?=- Core flux density from VLASS
(3000MHz) (1)
89- 91 F3.1 mJy e_S3000(core) ? Core flux density from VLASS (3000MHz)
error
92 A1 --- n_S3000(core) [X] Note on S3000(core) (2)
94- 98 F5.2 --- alphacore ?=- Two-point or three-point spectral index
of the core based on available flux
densities
100-103 F4.2 --- e_alphacore ? Two-point or three-point spectral index
error
105-133 A29 --- Notes Notes
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Note (1): No value for no detection or core not resolved from the extended
emission in the respective radio sky survey.
Note (2): X represents the radio source lying outside the sky coverage area.
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Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- SrNo Sequential number
4- 5 I2 h RAh Right ascension (J2000) of G-DDRGs hosted by
the brightest cluster galaxies
7- 8 I2 min RAm Right ascension (J2000) of G-DDRGs hosted by
the brightest cluster galaxies
10- 14 F5.2 s RAs Right ascension (J2000) of G-DDRGs hosted by
the brightest cluster galaxies
16 A1 --- DE- Declination sign (J2000) of G-DDRGs hosted
by the brightest cluster galaxies
17- 18 I2 deg DEd Declination (J2000) of G-DDRGs hosted by
the brightest cluster galaxies
20- 21 I2 arcmin DEm Declination (J2000) of G-DDRGs hosted by
the brightest cluster galaxies
23- 27 F5.2 arcsec DEs Declination (J2000) of G-DDRGs hosted
by the brightest cluster galaxies
29- 44 A16 --- Cluster Name
46- 51 F6.4 --- z Spectroscopic redshift
52 A1 --- n_z [+] + if photometric redshift
54- 57 F4.1 mag rmag r magnitude
59- 62 F4.2 Mpc r500 ?=- Radius within which the mean density is
500 times the critical density of the
Universe
64- 68 F5.2 --- RL*500 ?=- Cluster richness parameter
70- 71 I2 --- N500 ?=- Number of galaxies within r500
73- 76 F4.2 10+14Msun M500 ?=- Mass within r500
77 A1 --- n_M500 [*] * for mass from Gao et al.,
2020PASP..132b4101G 2020PASP..132b4101G, Cat. J/PASP/132/B4101
78-131 A54 --- Ref Reference
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Global notes:
Note (G1): Parent sample from which the source has been taken and literature
parent sample as follows:
S = Hardcastle et al. (2023A&A...678A.151H 2023A&A...678A.151H, Cat. J/A+A/678/A151)
* = Oei et al. (2023A&A...672A.163O 2023A&A...672A.163O, Cat. J/A+A/672/A163)
a = Koziel-Wierzbowska et al. (2020ApJS..247...53K 2020ApJS..247...53K, cat. J/ApJS/247/53)
b = Dabhade et al. (2020A&A...635A...5D 2020A&A...635A...5D, Cat. J/A+A/635/A5)
c = Mahatma et al. (2019A&A...622A..13M 2019A&A...622A..13M, Cat. J/A+A/622/A13)
d = Nandi & Saikia (2012BASI...40..121N 2012BASI...40..121N)
e = Renteria Macario & Andernach (2017, arXiv e-prints, arXiv:1710.10731)
f = Saikia et al. (2006MNRAS.366.1391S 2006MNRAS.366.1391S)
g = Schoenmakers et al. (1999A&A...341...44S 1999A&A...341...44S)
h = Schoenmakers et al. (2000MNRAS.315..371S 2000MNRAS.315..371S)
i = Dabhade et al. (2020A&A...642A.153D 2020A&A...642A.153D, Cat. J/A+A/642/A153)
j = Simonte et al. (2022MNRAS.515.2032S 2022MNRAS.515.2032S, Cat. J/MNRAS/515/2032)
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History:
From electronic version of the journal
References:
Dabhade et al., Paper I 2020A&A...642A.153D 2020A&A...642A.153D, Cat. J/A+A/642/A153
Dabhade et al., Paper II 2020A&A...643A.111D 2020A&A...643A.111D
Mahato et al., Paper III 2022A&A...660A..59M 2022A&A...660A..59M, Cat. J/A+A/660/A59
Sankhyayan & Dabhade, Paper IV 2024A&A...687L...8S 2024A&A...687L...8S
(End) Patricia Vannier [CDS] 28-Aug-2025