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http://hdl.handle.net/2289/6872
Title: | What Are "X-Shaped" radio sources telling Us? II. properties of a sample of 87 |
Authors: | Saripalli, Lakshmi Roberts, David H |
Keywords: | radio continuum galaxies |
Issue Date: | Jan-2018 |
Publisher: | IOP Sciences for The American Astronomical Society |
Citation: | Astrophysical Journal, 2018, Vol. 852, p48 |
Abstract: | In an earlier paper, we presented Jansky Very Large Array multi-frequency, multi-array continuum imaging of a unique sample of low-axial ratio radio galaxies. In this paper, the second in the series, we examine the images to learn the phenomenology of how the off-axis emission relates to the main radio source. Inversion-symmetric offset emission appears to be bimodal and to originate from one of two strategic locations: outer ends of radio lobes (outer-deviation) or from inner ends (inner-deviation). The latter sources are almost always associated with edge-brightened sources. With S- and Z-shaped sources being a subset of outer-deviation sources, this class lends itself naturally to explanations involving black hole axis precession. Our data allow us to present a plausible model for the more enigmatic inner-deviation sources with impressive wings; as for outer-deviation sources these too require black hole axis shifts, although they also require plasma backflows into relic channels. Evolution in morphology over time relates the variety in structures in inner-deviation sources including XRGs. With features such as non-collinearities, central inner-S "spine," corresponding lobe emission peaks, double and protruding hotspots not uncommon, black hole axis precession, drifts, or flips could be active in a significant fraction of radio sources with prominent off-axis emission. At least 4% of radio galaxies appear to undergo black hole axis rotation. Quasars offer a key signature for recognizing rotating axes. With a rich haul of sources that have likely undergone axis rotation, our work shows the usefulness of low-axial ratio sources in pursuing searches for binary supermassive black holes. |
Description: | Open Access |
URI: | http://hdl.handle.net/2289/6872 |
ISSN: | 0004-637X 1538-4357-(Online) |
Alternative Location: | http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1710.01652 http://arxiv.org/abs/1710.01652 http://dx.doi.org/10.3847/1538-4357/aa9c4b |
Copyright: | 2018 American Astronomical Society |
Appears in Collections: | Research Papers (A&A) |
Files in This Item:
File | Description | Size | Format | |
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2018_AsPJ_852_48.pdf | Open Access | 940 kB | Adobe PDF | View/Open |
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