Pierce, J.C.S. orcid.org/0000-0002-8250-9083, Tadhunter, C.N. and Morganti, R. (2020) The radio properties of high-excitation radio galaxies with intermediate radio powers. Monthly Notices of the Royal Astronomical Society, 494 (2). pp. 2053-2067. ISSN 0035-8711
Abstract
In the past decade, high-sensitivity radio surveys have revealed that the local radio active galactic nucleus population is dominated by moderate-to-low power sources with emission that is compact on galaxy scales. High-excitation radio galaxies (HERGs) with intermediate radio powers (22.5 < log (L1.4 GHz) < 25.0 W Hz−1) form an important sub-group of this population, since there is strong evidence that they also drive multiphase outflows on the scales of galaxy bulges. Here, we present high-resolution Very Large Array observations at 1.5, 4.5, and 7.5 GHz of a sample of 16 such HERGs in the local universe (z < 0.1), conducted in order to investigate the morphology, extent, and spectra of their radio emission in detail, down to sub-kpc scales. We find that the majority (56 per cent) have unresolved structures at the limiting angular resolution of the observations (∼0.3 arcsec). Although similar in the compactness of their radio structures, these sources have steep radio spectra and host galaxy properties that distinguish them from local low-excitation radio galaxies that are unresolved on similar scales. The remaining sources exhibit extended radio structures with projected diameters ∼1.4–19.0 kpc and a variety of morphologies: three double-lobed; two large-scale diffuse; one jetted and ‘S-shaped’; one undetermined. Only 19 per cent of the sample therefore exhibit the double-lobed/edge-brightened structures often associated with their counterparts at high and low radio powers: radio-powerful HERGs and Seyfert galaxies, respectively. Additional high-resolution observations are required to investigate this further, and to probe the ≲300 pc scales on which some Seyfert galaxies show extended structures.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | galaxies: active; galaxies: jets; galaxies: nuclei; radio continuum: galaxies |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/R000964/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Feb 2021 14:53 |
Last Modified: | 22 Feb 2021 14:59 |
Status: | Published |
Publisher: | Oxford University Press (OUP) |
Refereed: | Yes |
Identification Number: | 10.1093/mnras/staa531 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:171354 |