NGC 326: X-shaped no more
Date Issued
2019
Author(s)
Hardcastle, M. J.
•
Croston, J. H.
•
Shimwell, T. W.
•
Tasse, C.
•
Gürkan, G.
•
Morganti, R.
•
•
Röttgering, H. J. A.
•
van Weeren, R. J.
•
Williams, W. L.
Abstract
We present new 144-MHz Low-Frequency Array (LOFAR) observations of the prototypical `X-shaped' radio galaxy NGC 326, which show that the formerly known wings of the radio lobes extend smoothly into a large-scale, complex radio structure. We argue that this structure is most likely the result of hydrodynamical effects in an ongoing group or cluster merger, for which pre-existing X-ray and optical data provide independent evidence. The large-scale radio structure is hard to explain purely in terms of jet reorientation due to the merger of binary black holes, a previously proposed explanation for the inner structure of NGC 326. For this reason, we suggest that the simplest model is one in which the merger-related hydrodynamical processes account for all the source structure, though we do not rule out the possibility that a black hole merger has occurred. Inference of the black hole-black hole merger rate from observations of X-shaped sources should be carried out with caution in the absence of deep, sensitive low-frequency observations. Some X-shaped sources may be signposts of cluster merger activity, and it would be useful to investigate the environments of these objects more generally.
Volume
488
Issue
3
Start page
3416
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.488.3416H
Rights
open.access
File(s)![Thumbnail Image]()
Loading...
Name
Hardcastle_2019.pdf
Description
PDF editoriale
Size
1.62 MB
Format
Adobe PDF
Checksum (MD5)
8c8c60d2173f9f8aa49a6efe634c0586