J/AJ/154/169 GMRT observations of head-tail radio galaxies (Sebastian+, 2017)
Giant Metrewave Radio Telescope observations of head-tail radio galaxies.
Sebastian B., Lal D.V., Rao A.P.
<Astron. J., 154, 169-169 (2017)>
=2017AJ....154..169S 2017AJ....154..169S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Radio continuum ; Redshifts
Keywords: galaxies: active - galaxies: jets - galaxies: nuclei -
galaxies: structure - radio continuum: galaxies
Abstract:
We present results from a study of seven large known head-tail radio
galaxies based on observations using the Giant Metrewave Radio
Telescope at 240 and 610 MHz. These observations are used to study the
radio morphologies and distribution of the spectral indices across the
sources. The overall morphology of the radio tails of these sources is
suggestive of random motions of the optical host around the cluster
potential. The presence of multiple bends and wiggles in several
head-tail sources is possibly due to the precessing radio jets. We
find steepening of the spectral index along the radio tails. The
prevailing equipartition magnetic field also decreases along the radio
tails of these sources. These steepening trends are attributed to the
synchrotron aging of plasma toward the ends of the tails. The
dynamical ages of these sample sources have been estimated to be
∼108 yr, which is a factor of six more than the age estimates from
the radiative losses due to synchrotron cooling.
Description:
Owen & Ledlow (1997ApJS..108...41O 1997ApJS..108...41O) have surveyed over 500 Abell clusters
of galaxies using the Very Large Array (VLA) at λ=21 cm, and they
presented radio maps of sources with complex or multiple features.
They detect and list candidate head-tail radio sources in these clusters.
From this list of candidate head-tail radio sources, along with the
head-tail sources known in the literature, we choose only nearby, z<0.05,
and confirmed head-tail galaxies with an angular size of galaxy tail larger
than 5 arcmin as our sample source. Our final sample consisted of seven
head-tail radio galaxies, listed in Table 1.
Our sample of seven head-tail radio galaxies was observed using the
simultaneous dual-frequency (240 and 610 MHz) mode of GMRT, except for
two sources, where data at 240 MHz were marred by radio frequency
interference (RFI) and were later observed at 325 MHz.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 15 Sources
table2.dat 83 61 Distance, Size, Radio Luminosity, and
Equipartition Parameters along with Radiative
Age for the Sample Sources
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See also:
J/ApJS/120/147 : Radio sources in 14 Abell clusters (Marvel+, 1999)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Object name
15- 26 A12 --- Cluster Cluster name
28- 32 F5.3 --- z [0.019/0.043]? Redshift
34- 35 I2 h RAh ? Hour of Right Ascension (J2000)
37- 38 I2 min RAm ? Minute of Right Ascension (J2000)
40- 44 F5.2 s RAs ? Second of Right Ascension (J2000)
46 A1 --- DE- Sign of the Declination (J2000)
47- 48 I2 deg DEd ? Degree of Declination (J2000)
50- 51 I2 arcmin DEm ? Arcminute of Declination (J2000)
53- 56 F4.1 arcsec DEs ? Arcsecond of Declination (J2000)
58- 61 F4.1 arcmin Size [5/15]? Angular size
63- 67 F5.3 kpc/arcsec Scale [0.385/0.841]? Linear scale for our adopted
cosmology
69- 79 A11 "date" Date Date of observation
81- 82 I2 MHz Dnu [8/32]? Bandwidth Δν
84- 88 F5.1 MHz nuCen [240.3/618.3]? Center frequency νcen
90- 94 A5 --- FluxC Flux density calibrator
96-103 A8 --- PhaseC Phase calibrator
105-108 F4.2 h Ton [1.25/6.5]? On-source integration time
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Object name
15- 19 F5.1 kpc Dist [0/401.4] Distance from the head along
the tail
21- 27 E7.3 cm+3 V [1e+40/8.2e+69] Cylindrical volume of
the region
29- 35 E7.3 10-7W Lum [1.6e+38/2.2e+40] Radio luminosity (in erg/s)
37- 42 E6.2 10-7W e_Lum [3e+37/5e+39] Uncertainty in Lum (in erg/s)
44- 48 F5.2 --- alpha [-2.31/-0.2] Spectral index (α) between
242 MHz (or 325 MHz) and 610 MHz
50- 52 F3.1 mugauss Bmin [0.8/2.6] Minimum magnetic field Bmin
54- 62 E9.4 erg/cm3 Umin [1.1e-14/27.4e-14] Minimum energy density
Umin
64- 70 E7.2 erg/cm3 e_Umin [1e-15/1.1e-14] Uncertainty in Umin
72- 78 E7.2 0.1Pa Pmin [3e-15/9.1e-14] Minimum pressure Pmin
(in dyne/cm2)
80- 83 F4.1 Myr Age [40/58.7] Radiative age
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 23-Jul-2018