2022A&A...658A...5T


Query : 2022A&A...658A...5T

2022A&A...658A...5T - Astronomy and Astrophysics, volume 658A, 5-5 (2022/2-1)

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., 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., ROTTGERING H.J.A., BOTTEON A., SWEIJEN F., TASSE C., BRUGGEN M., MOLDON J., SHIMWELL T. and BRUNETTI G.

Abstract (from CDS):

The prominent radio source Hercules A features complex structures in its radio lobes. Although it is 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 (<300 MHz) of Hercules A, made with the International LOFAR Telescope. With the addition of data from the Karl G. Jansky Very Large Array, we mapped the structure of the lobes from 144 MHz to 7 GHz. 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 by an inner-lobe model, where 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.

Abstract Copyright: © R. Timmerman et al. 2022

Journal keyword(s): large-scale structure of Universe - galaxies: active - radio continuum: galaxies - radiation mechanisms: non-thermal - galaxies: clusters: individual: Hercules A

VizieR on-line data: <Available at CDS (J/A+A/658/A5): list.dat fits/*>

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2269 1
2 ZwCl 0735+7421 ClG 07 41 40.3 +74 14 58     17.70     ~ 254 0
3 NAME Hya A LIN 09 18 05.66848602 -12 05 43.8060823   14.38 14.8     ~ 1014 1
4 3C 286 Sy1 13 31 08.2883506368 +30 30 32.960091564   17.51 17.25     ~ 4351 2
5 3C 295 Sy2 14 11 20.6 +52 12 09   22.34 20.80 18.54   ~ 983 5
6 ICRF J165103.6+012923 BLL 16 51 03.66236951 +01 29 23.4581070   22.7 21.2 20.50   ~ 74 1
7 NAME Hercules A rG 16 51 07.9886687784 +04 59 35.547131472     18.25     ~ 467 1
8 ACT-CL J2344.7-4243 ClG 23 44 43.9 -42 43 11           ~ 192 0

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