J/A+A/622/A13 VLA double-double radio galaxy candidates images (Mahatma+, 2019)
LoTSS DR1: Double-double radio galaxies in the HETDEX field.
Mahatma V.H., Hardcastle M.J., Williams W.L., Best P.N., Croston J.H.,
Duncan K., Mingo B., Morganti R., Brienza M., Cochrane R.K., Guerkan G.,
Harwood J.J., Jarvis M.J., Jamrozy M., Jurlin N., Morabito L.K.,
Roettgering H.J.A., Sabater J., Shimwell T.W., Smith D.J.B., Shulevski A.,
Tasse C.
<Astron. Astrophys. 622, A13 (2019)>
=2019A&A...622A..13M 2019A&A...622A..13M (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, radio
Keywords: galaxies: active - galaxies: jets - radio continuum: galaxies
Abstract:
Double-double radio galaxies (DDRGs) represent a short but unique
phase in the life-cycle of some of the most powerful radio-loud active
galactic nuclei (RLAGN). These galaxies display large-scale remnant
radio plasma in the intergalactic medium left behind by a past episode
of active galactic nuclei (AGN) activity, and meanwhile, the radio
jets have restarted in a new episode. The knowledge of what causes the
jets to switch off and restart is crucial to our understanding of
galaxy evolution, while it is important to know if DDRGs form a host
galaxy dichotomy relative to RLAGN.
The sensitivity and field of view of LOFAR enables the observation of
DDRGs on a population basis rather than single-source observations.
Using statistical comparisons with a control sample of RLAGN, we may
obtain insights into the nature of DDRGs in the context of their host
galaxies, where physical differences in their hosts compared to RLAGN
as a population may allow us to infer the conditions that drive
restarting jets.
We utilised the LOFAR Two-Metre Sky Survey (LoTSS) DR1, using a visual
identification method to compile a sample of morphologically selected
candidate DDRGs, showing two pairs of radio lobes. To confirm the
restarted nature in each of the candidate sources, we obtained
follow-up observations with the Karl. G. Jansky Very Large Array (VLA)
at higher resolution to observe the inner lobes or restarted jets, the
confirmation of which created a robust sample of 33 DDRGs.We created a
comparison sample of 777 RLAGN, matching the luminosity distribution
of the DDRG sample, and compared the optical and infrared magnitudes
and colours of their host galaxies.
We find that there is no statistically significant difference in the
brightness of the host galaxies between double-doubles and
single-cycle RLAGN. The DDRG and RLAGN samples also have similar
distributions in WISE mid-infrared colours, indicating similar ages of
stellar populations and dust levels in the hosts of DDRGs. We conclude
that DDRGs and 'normal' RLAGN are hosted by galaxies of the same
type, and that DDRG activity is simply a normal part of the life cycle
of RLAGN. Restarted jets, particularly for the class of low-excitation
radio galaxies, rather than being a product of a particular event in
the life of a host galaxy, must instead be caused by smaller scale
changes, such as in the accretion system surrounding the black hole.
Description:
We obtained snapshot VLA observations of our 40 candidate DDRGs at
1.4GHz in the A array (broadband setup).
Two sets of observations were conducted on the 27 and 28 March 2018,
both consisting of 5-minute snapshot observations of each target
source (as detailed in Table 1) with the same hardware setup.
Calibration using VLA CASA pipeline, 3C286 as primary flux calibrator,
self-calibration performed for brightest objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 173 40 List of fits images
fits/* . 40 Individual fits images
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See also:
J/A+A/622/A1 : LOFAR Two-metre Sky Survey DR1 source catalog (Shimwell+, 2019)
J/A+A/622/A4 : LOFAR observations XMM-LSS field (Hale+, 2019)
J/A+A/622/A8 : NGC 3184, 4736, 5055 and 5194 LOFAR & WSRT maps (Heesen+, 2019)
J/A+A/622/A11 : LoTSS/HETDEX. Optical quasars. I. (Guerkan+, 2019)
J/A+A/622/A15 : Broad absorption line quasars in LDR1 (Morabito+, 2019)
J/A+A/622/A22 : Abell 1914 multiwavelength radio images (Mandal+, 2019)
J/A+A/622/A23 : LoTSS HCG and MLCG systems (Nikiel-wroczynski+, 2019)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Name Name (ILTJHHMMSS.ss+DDMMSS.s) (1)
23 A1 --- n_Name [+] Note on name (1) (2)
25- 26 I2 h RAh Right ascension (J2000) (1)
28- 29 I2 min RAm Right ascension (J2000) (1)
31- 35 F5.2 s RAs Right ascension (J2000) (1)
37 A1 --- DE- Declination sign (J2000) (1)
38- 39 I2 deg DEd Declination (J2000) (1)
41- 42 I2 arcmin DEm Declination (J2000) (1)
44- 48 F5.2 arcsec DEs Declination (J2000) (1)
50- 76 A27 --- OName Other name (1) (3)
77 A1 --- u_Name [*] * for Misidentified source
(see Section 2.2.3 of the paper)
78- 82 F5.3 --- z ? Redshift (1)
83 A1 --- n_z [sp] Spectroscopic (s) or
photometric (p) redshift (1)
85- 88 I4 --- Nx Number of pixels along X-axis
90- 93 I4 --- Ny Number of pixels along Y-axis
95-120 A26 "datime" Obs.date Observation date (YYYY-MM-DDThh.mm.ss.ssssss)
122-127 F6.4 GHz Freq [1.5195] Observed frequency
129-133 I5 Kibyte size Size of FITS file
135-173 A39 --- FileName Name of FITS file, in subdirectory fits
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Note (1): From table 1 of the paper.
Note (2): + for sources removed as having a lack of evidence of being classed
as a double-double radio galaxy (DDRG).
Note (3): host galaxy identifications were based on a visual method of
cross-matching the LOFAR source with FIRST core emission at the position of
a Pan-STARSS or WISE-detected galaxy, if any.
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Acknowledgements:
Vijay Mahatma, v.mahatma2(at)herts.ac.uk
References:
Shimwell et al., Paper I 2019A&A...622A...1S 2019A&A...622A...1S, Cat. J/A+A/622/A1
Williams et al., Paper II 2019A&A...622A...2W 2019A&A...622A...2W
Duncan et al., Paper III 2019A&A...622A...3D 2019A&A...622A...3D
Hale et al., Paper IV 2019A&A...622A...4H 2019A&A...622A...4H, Cat. J/A+A/622/A4
de Gasperin et al., Paper V 2019A&A...622A...5D 2019A&A...622A...5D
Arias et al., Paper VI 2019A&A...622A...6A 2019A&A...622A...6A
Emig et al., Paper VII 2019A&A...622A...7E 2019A&A...622A...7E
Heesen et al., Paper VIII 2019A&A...622A...8H 2019A&A...622A...8H, Cat, J/A+A/622/A8
Miskolczi et al., Paper IX 2019A&A...622A...9M 2019A&A...622A...9M
Croston et al., Paper X 2019A&A...622A..10C 2019A&A...622A..10C
Gurkan et al., Paper XI 2019A&A...622A..11G 2019A&A...622A..11G, Cat. J/A+A/622/A11
Hardcastle et al., Paper XII 2019A&A...622A..12H 2019A&A...622A..12H
Mahatma et al., Paper XIII 2019A&A...622A..13M 2019A&A...622A..13M, Cat. J/A+A/622/A13
Mooney et al., Paper XIV 2019A&A...622A..14M 2019A&A...622A..14M
Morabito et al., Paper XV 2019A&A...622A..15M 2019A&A...622A..15M, Cat. J/A+A/622/A15
O'Sullivan et al., Paper XVI 2019A&A...622A..16O 2019A&A...622A..16O
Sabater et al., Paper XVII 2019A&A...622A..17S 2019A&A...622A..17S
Stacey et al., Paper XVIII 2019A&A...622A..18S 2019A&A...622A..18S
Botteon et al., Paper XIX 2019A&A...622A..19B 2019A&A...622A..19B
Hoang et al., Paper XX 2019A&A...622A..20H 2019A&A...622A..20H
Hoang et al., Paper XXI 2019A&A...622A..21H 2019A&A...622A..21H
Mandal et al., Paper XXII 2019A&A...622A..22M 2019A&A...622A..22M, Cat. J/A+A/622/A22
Nikiel-Wroczynski et al., Paper XXIII 2019A&A...622A..23N 2019A&A...622A..23N
Savini et al., Paper XXIV 2019A&A...622A..24S 2019A&A...622A..24S
Wiber et al., Paper XXV 2019A&A...622A..25W 2019A&A...622A..25W
(End) Patricia Vannier [CDS] 15-Nov-2018