J/A+A/658/A5 Hercules A LOFAR and JVLA images (Timmerman+, 2022)
Origin of the ring structures in Hercules A.
Sub-arcsecond 144 MHz to 7 GHz observations.
Timmerman R., Van Weeren R.J., Callingham J.R., Cotton W.D., Perley R.A.,
Morabito L.K., Gizani N.A.B., Bridle A.H., O'Dea C.P., Baum S.A.,
Tremblay G.R., Kharb P., Kassim N.E., Roettgering H.J.A., Botteon A.,
Sweijen F., Tasse C., Brueggen M., Moldon J., Shimwell T., Brunetti G.
<Astron. Astrophys. 658, A5 (2022)>
=2022A&A...658A...5T 2022A&A...658A...5T (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, radio ; Radio continuum
Keywords: large-scale structure of Universe - galaxies: active -
radio continuum: galaxies - radiation mechanisms: non-thermal -
galaxies: clusters: individual: Hercules A
Abstract:
The prominent radio source Hercules A features complex structures in
its radio lobes. Despite being one of the most comprehensively studied
sources in the radio sky, the origin of the ring structures in the
Hercules A radio lobes remains an open question. We present the first
sub-arcsecond angular resolution images at low frequencies (<300MHZ)
of Hercules A, made with the International LOFAR Telescope. With the
addition of data from the Karl G. Jansky Very Large Array, we map the
structure of the lobes from 144MHz to 7GHz. We explore the origin of
the rings within the lobes of Hercules A, and test whether their
properties are best described by a shock model where shock waves are
produced by the jet propagating in the radio lobe, or an inner-lobe
model in which the rings are formed by decelerated jetted plasma. From
spectral index mapping, our large frequency coverage reveals that the
curvature of the different ring spectra increases with distance away
from the central active galactic nucleus. We demonstrate that the
spectral shape of the rings is consistent with synchrotron aging,
which speaks in favor of an inner-lobe model, where the rings are
formed from the deposition of material from past periods of
intermittent core activity.
Description:
Reduced LOFAR and JVLA images of Hercules A at 144MHz (LOFAR HBA),
1.5GHz (JVLA L band) and 7GHz (JVLA C Band).
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------
16 51 08.14 +04 59 33.6 3C 348 = Hercules A
-------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 110 3 List of fits images
fits/* . 3 Individual fits images
--------------------------------------------------------------------------------
See also:
J/A+A/658/A2 : LOFAR Long-Baseline Calibrator Survey. II. (Jackson+, 2022)
J/A+A/658/A4 : LOFAR imaging of Arp299 at 150MHz (Ramirez-Olivencia, 2022)
J/A+A/658/A6 : 3C293 high and low resolution maps (Kukreti+, 2022)
J/A+A/658/A8 : Resolved jet of 3C 273 at 150 MHz (Harwood+, 2022)
J/A+A/658/A10 : 3C295 LOFAR, MERLIN and VLA images (Bonnassieux+, 2022)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 48 A19 "datime" Obs.date Observation date
50- 54 F5.3 GHz Freq Observed frequency
56- 60 I5 Kibyte size Size of FITS file
62- 73 A12 --- FileName Name of FITS file, in subdirectory fits
75-110 A36 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Roland Timmerman, rtimmerman(at)strw.leidenuniv.nl
References:
Morabito et al., Paper I 2022A&A...658A...1M 2022A&A...658A...1M
Jackson et al., Paper II 2022A&A...658A...2J 2022A&A...658A...2J, Cat. J/A+A/658/A2
Sweijen et al., Paper III 2022A&A...658A...3S 2022A&A...658A...3S
Ramirez-Olivencia et al., Paper IV 2022A&A...658A...4R 2022A&A...658A...4R, Cat, J/A+A/658/A4
Kukreti et al., Paper VI 2022A&A...658A...6K 2022A&A...658A...6K, Cat, J/A+A/658/A6
Badole et al., Paper VII 2022A&A...658A...7B 2022A&A...658A...7B
Harwood et al., Paper VIII 2022A&A...658A...8H 2022A&A...658A...8H, Cat, J/A+A/658/A8
Groeneveld et al., Paper IX 2022A&A...658A...9G 2022A&A...658A...9G
Bonnassieux et al., Paper X 2022A&A...658A..10B 2022A&A...658A..10B, Cat. J/A+A/658/A10
(End) Patricia Vannier [CDS] 28-Jul-2021