Origin of the ring structures in Hercules A. Sub-arcsecond 144 MHz to 7 GHz observations
Journal
Date Issued
2022
Author(s)
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.
•
Röttgering, H. J. A.
•
•
Sweijen, F.
•
Tasse, C.
•
Brüggen, M.
•
Moldon, J.
•
Shimwell, T.
•
Abstract
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.
The reduced images are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/658/A5...
Volume
658
Start page
A5
Issn Identifier
0004-6361
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
aa40880-21.pdf
Description
Pdf editoriale
Size
5.93 MB
Format
Adobe PDF
Checksum (MD5)
03ce29632596867108ce3477fb881de3
Loading...
Name
2108.07287v1.pdf
Description
Postprint
Size
5.93 MB
Format
Adobe PDF
Checksum (MD5)
0f3e7addad864df1d724cc8e58d0aa17