The Open UniversitySkip to content
 

LoTSS/HETDEX: Optical quasars - I. Low-frequency radio properties of optically selected quasars

Gürkan, Gülay; Hardcastle, M. J.; Best, P. N.; Morabito, L. K.; Prandoni, I.; Jarvis, M. J.; Duncan, K. J.; Calistro Rivera, G.; Callingham, J. R.; Cochrane, R. K.; Croston, J. H.; Heald, G.; Mingo, B.; Mooney, S.; Sabater, J.; Röttgering, H. J. A.; Shimwell, T. W.; Smith, D. J. B.; Tasse, C. and Williams, W. L. (2019). LoTSS/HETDEX: Optical quasars - I. Low-frequency radio properties of optically selected quasars. Astronomy & Astrophysics, 622, article no. A11.

Full text available as:
[img]
Preview
PDF (Version of Record) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
Download (14MB) | Preview
DOI (Digital Object Identifier) Link: https://doi.org/10.1051/0004-6361/201833892
Google Scholar: Look up in Google Scholar

Abstract

The radio-loud/radio-quiet (RL/RQ) dichotomy in quasars is still an open question. Although it is thought that accretion onto supermassive black holes in the centre the host galaxies of quasars is responsible for some radio continuum emission, there is still a debate as to whether star formation or active galactic nuclei (AGN) activity dominate the radio continuum luminosity. To date, radio emission in quasars has been investigated almost exclusively using high-frequency observations in which the Doppler boosting might have an important effect on the measured radio luminosity, whereas extended structures, best observed at low radio frequencies, are not affected by the Doppler enhancement. We used a sample of quasars selected by their optical spectra in conjunction with sensitive and high-resolution low-frequency radio data provided by the LOw Frequency ARray (LOFAR) as part of the LOFAR Two-Metre Sky Survey (LoTSS) to investigate their radio properties using the radio loudness parameter (R =L144 MHz/Li band). The examination of the radio continuum emission and RL/RQ dichotomy in quasars exhibits that quasars show a wide continuum of radio properties (i.e. no clear bimodality in the distribution of ℛ). Radio continuum emission at low frequencies in low-luminosity quasars is consistent with being dominated by star formation. We see a significant albeit weak dependency of ℛ on the source nuclear parameters. For the first time, we are able to resolve radio morphologies of a considerable number of quasars. All these crucial results highlight the impact of the deep and high-resolution low-frequency radio surveys that foreshadow the compelling science cases for the Square Kilometre Array (SKA).

Item Type: Journal Item
Copyright Holders: 2019 ESO
ISSN: 1432-0746
Project Funding Details:
Funded Project NameProject IDFunding Body
Jet energy injection in galaxy groups and clusters - transfer of CG funding (Transfer in)ST/R00109X/1STFC (Science & Technology Facilities Council)
Jet physics and impact via LOFAR extragalactic surveysST/R000794/1STFC (Science & Technology Facilities Council)
Keywords: quasars: normal; optical:quasars; radio:quasars
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Astronomy
Item ID: 57845
Depositing User: Judith Croston
Date Deposited: 06 Dec 2018 11:16
Last Modified: 02 May 2019 07:41
URI: http://oro.open.ac.uk/id/eprint/57845
Share this page:

Metrics

Altmetrics from Altmetric

Citations from Dimensions

Download history for this item

These details should be considered as only a guide to the number of downloads performed manually. Algorithmic methods have been applied in an attempt to remove automated downloads from the displayed statistics but no guarantee can be made as to the accuracy of the figures.

Actions (login may be required)

Policies | Disclaimer

© The Open University   contact the OU