J/A+A/635/A5 LoTSS giant radio galaxies. I. (Dabhade+, 2020)
Giant radio galaxies in the LOFAR Two-metre Sky Survey.
I. Radio and environmental properties.
Dabhade P., Roettgering H.J.A., Bagchi J ., Shimwell T.W., Hardcastle M.J.,
Sankhyayan S., Morganti R., Jamrozy M., Shulevski A., Duncan K.J.
<Astron. Astrophys. 635, A5 (2020)>
=2020A&A...635A...5D 2020A&A...635A...5D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Redshifts ; Morphology
Keywords: galaxies: jets - galaxies: active - radio continuum: galaxies -
quasars: general
Abstract:
Giant radio galaxies (GRGs) are a subclass of radio galaxies, which
have grown to megaparsec scales. GRGs are much rarer than normal-sized
radio galaxies (<0.7Mpc) and the reason for their gigantic sizes is
still debated. Here, we report on the biggest sample of GRGs
identified to date. These objects were found in the LOFAR Two-metre
Sky Survey (LoTSS) first data release images, which cover a 424 deg2
region. Of the 239 GRGs found, 225 are new discoveries. The GRGs in
our sample have sizes ranging from 0.7Mpc to 3.5Mpc and have redshifts
(z) between 0.1 and 2.3. Seven GRGs have sizes above 2Mpc and one has
a size of ∼3.5Mpc. The sample contains 40 GRGs hosted by
spectroscopically confirmed quasars. Here, we present the search
techniques employed and the resulting catalogue of the newly
discovered large sample of GRGs along with their radio properties. In
this paper, we also show for the first time that the spectral index of
GRGs is similar to that of normal-sized radio galaxies, indicating
that most of the GRG population is not dead or is not similar to a
remnant-type radio galaxy. We find that 20 out of 239 GRGs in our
sample are located at the centres of clusters and we present our
analysis on their cluster environment and radio morphology.
Description:
The VAC of 318520 radio sources was at first refined based on the
point source completeness, which is 90% at an integrated flux density
of 0.5mJy for LoTSS DR1 (Shimwell et al., 2019, Cat. J/A+A/622/A1).
The final sample size of GRGs from the VAC is 186 GRGs.
An independent manual visual search (MVS) was also carried out to
search for GRGs in LoTSS DR1 to look for additional GRGs that were
missed in the semi-automated method employed on the VAC.
We combined both GRG samples (VAC and MVS) to form the final GRG
catalogue of 239 GRGs (Table. A1).
We find a total of 20 GRGs (Table A2) from our sample of 239 to be
BCGs residing in dense cluster environments and hosted by BCGs of the
clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 117 239 All of the 239 GRGs found from the LoTSS
tablea2.dat 86 20 LoTSS GRGs in galaxy clusters
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See also:
J/ApJS/191/254 : GMBCG galaxy cluster catalog from SDSS DR7 (Hao+, 2010)
J/ApJS/199/34 : Clusters of galaxies in SDSS-III (Wen+, 2012)
J/A+A/622/A1 : LOFAR Two-metre Sky Survey DR1 source catalog (Shimwell+ 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- SrNo Sequential number
5- 6 I2 h RAh Right ascension (J2000.0)
8- 9 I2 min RAm Right ascension (J2000.0)
11- 15 F5.2 s RAs Right ascension (J2000.0)
17 A1 --- DE- Declination sign (J2000.0)
18- 19 I2 deg DEd Declination (J2000.0)
21- 22 I2 arcmin DEm Declination (J2000.0)
24- 28 F5.2 arcsec DEs Declination (J2000.0)
30 A1 --- Class [GQ] type of host of the GRG (1)
32- 38 F7.5 --- z Redshift
40- 46 F7.5 --- e_z rms uncertainty on redshift
48- 55 A8 --- n_z Redshift type and origin (2)
57- 59 I3 arcsec Size Angular size
61- 64 F4.2 Mpc SizeP Projected linear size
66- 69 I4 mJy S144MHz Integrated flux at 144MHz
71- 74 I4 mJy e_S144MHz rms uncertainty on integrated flux at 144MHz
76- 81 F6.2 10+26W/Hz P144MHz Radio power at 144MHz
83- 87 F5.2 10+26W/Hz e_P144MHz rms uncertainty on radio power at 144MHz
89 A1 --- l_SI [<] Limit flag on SI
90- 93 F4.2 --- SI ?=- Integrated spectral index computed
between 1400MHz (NVSS) flux and 144MHz
(LoTSS) fluxes
96- 99 F4.2 --- e_SI ?=- rms uncertainty on SI
101-103 A3 --- FR Morphological type of the GRG (3)
105-109 F5.2 mag rmag r band magnitude of the host galaxies of
the GRGs obtained from SDSS (4)
111-114 F4.2 mag e_rmag rms uncertainty on rmag
116-117 I2 --- Ref ?=- Reference for the GRGs already known
in literature (5)
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Note (1): Type of host of the GRG as follows:
G = galaxy
Q = quasar
Note (2): Redshift type and origin as follows:
spz_sdss = spectroscopic redshift from SDSS
phz_sdss = photometric redshift from SDSS
phz_vac = redshifts from VAC
Note (3): Morphological type of the GRG as follows:
I = FR-I type
II = FR-II type
III = HyMoRS
Note (4): For sources 162 and 233, in the absence of reliable magnitudes from
SDSS, we have given r band magnitudes from PAN-STARRS.
Note (5): References as follows:
1 = Amirkhanyan et al. (2015, Astrophysical Bulletin, 70, 45)
2 = Amirkhanyan (2016, Astrophysical Bulletin, 71, 384)
3 = Cotter et al. (1996MNRAS.281.1081C 1996MNRAS.281.1081C)
4 = Koziel-Wierzbowska & Stasinska (2011, Cat. J/MNRAS/415/1013)
5 = Machalski (1998, Cat J/A+AS/128/153)
6 = Machalski et al. (2001A&A...371..445M 2001A&A...371..445M)
7 = Nilsson (1998, Cat. J/A+AS/132/31)
8 = Renteria Macario & Andernach (2017, arXiv:1710.10731)
9 = Thwala et al. (2019MNRAS.485.1938T 2019MNRAS.485.1938T)
10 = Kuzmicz et al. (2018, Cat. J/ApJS/238/9)
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- SrNo [1/20] Sequential number
4- 28 A25 --- Cluster Cluster name (1)
30- 31 I2 h RAh Right ascension (J2000.0)
33- 34 I2 min RAm Right ascension (J2000.0)
36- 40 F5.2 s RAs Right ascension (J2000.0)
42 A1 --- DE- Declination sign (J2000.0)
43- 44 I2 deg DEd Declination (J2000.0)
46- 47 I2 arcmin DEm Declination (J2000.0)
49- 53 F5.2 arcsec DEs Declination (J2000.0)
55- 61 F7.5 --- zsp Spectroscopic redshift
63- 69 F7.5 --- e_zsp rms uncertainty on zsp
70 A1 --- n_zsp [*] * for photometric redshift in zsp
72- 74 F3.1 Mpc r200 ?=- Radius within which the mean density of a
cluster is 200 times of the critical density
of the Universe (2)
76- 79 F4.1 --- RL* ?=- Cluster richness parameter (2)
81- 83 F3.1 10+14Msun M200 ?=- Mass of the cluster within r200 (3)
85- 86 I2 --- N200 ?=- Number of galaxies within r200
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Note (1): GMBCG names from Hao et al. (2010, Cat. J/ApJS/191/254).
Note (2): taken from the WHL galaxy cluster catalogue, Weh et al.,
2012, Cat. J/ApJS/199/34
Note (3): computed from Eq.2 of Wen et al. (2012ApJS..199...34W 2012ApJS..199...34W).
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Acknowledgements:
Pratik Dabhade, pratikdabhade13(at)gmail.com
(End) Patricia Vannier [CDS] 10-Feb-2020