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    Evidence that the AGN dominates the radio emission in z ~ 1 radio-quiet quasars

    252048.pdf (2.897Mb)
    Access Status
    Open access
    Authors
    White, Sarah
    Jarvis, M.
    Kalfountzou, E.
    Hardcastle, M.
    Verma, A.
    Cao Orjales, J.
    Stevens, J.
    Date
    2017
    Type
    Journal Article
    
    Metadata
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    Citation
    White, S. and Jarvis, M. and Kalfountzou, E. and Hardcastle, M. and Verma, A. and Cao Orjales, J. and Stevens, J. 2017. Evidence that the AGN dominates the radio emission in z ~ 1 radio-quiet quasars. Monthly Notices of the Royal Astronomical Society. 468 (1): pp. 217-238.
    Source Title
    Monthly Notices of the Royal Astronomical Society
    DOI
    10.1093/mnras/stx284
    ISSN
    0035-8711
    School
    Curtin Institute of Radio Astronomy (Physics)
    Remarks

    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

    URI
    http://hdl.handle.net/20.500.11937/52860
    Collection
    • Curtin Research Publications
    Abstract

    © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.In order to understand the role of radio-quiet quasars (RQQs) in galaxy evolution, we must determine the relative levels of accretion and star-formation activity within these objects. Previous work at low radio flux densities has shown that accretion makes a significant contribution to the total radio emission, in contrast with other quasar studies that suggest star formation dominates. To investigate, we use 70 RQQs from the Spitzer-Herschel Active Galaxy Survey. These quasars are all at z ~ 1, thereby minimizing evolutionary effects, and have been selected to span a factor of ~100 in optical luminosity, so that the luminosity dependence of their properties can be studied. We have imaged the sample using the Karl G. Jansky Very Large Array (JVLA), whose high sensitivity results in 35 RQQs being detected above 2s. This radio data set is combined with far-infrared luminosities derived from grey-body fitting to Herschel photometry. By exploiting the far-infrared-radio correlation observed for star-forming galaxies, and comparing two independent estimates of the star-formation rate, we show that star formation alone is not sufficient to explain the total radio emission. Considering RQQs above a 2s detection level in both the radio and the far-infrared, 92 per cent are accretion dominated, and the accretion process accounts for 80 per cent of the radio luminosity when summed across the objects. The radio emission connected with accretion appears to be correlated with the optical luminosity of the RQQ, whilst a weaker luminosity dependence is evident for the radio emission connected with star formation.

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