TY - JOUR
T1 - Winds as the origin of radio emission in z = 2.5 radio-quiet extremely red quasars
AU - Hwang, Hsiang Chih
AU - Zakamska, Nadia L.
AU - Alexandroff, Rachael M.
AU - Hamann, Fred
AU - Greene, Jenny E.
AU - Perrotta, Serena
AU - Richards, Gordon T.
N1 - Funding Information:
The authors are grateful to R. White, S. van Velzen, and U. Rau for technical discussions, to the anonymous referee for constructive suggestions, and to the staff of the National Radio Astronomical Observatory for technical support and assistance with data storage and processing. HCH would also like to acknowledge the helpful discussion with Y.-K. Chiang, A.-L. Sun, and K. Hall. NLZ is grateful to Johns Hopkins University for support via the Catalyst Award and to the Institute for Advanced Study for hospitality during multiple visits. RA is supported by a Postdoctoral Fellowship awarded by the Natural Science and Engineering Research Council of Canada. Support for this work was also provided in part by the National Aeronautics and Space Administration through Chandra Award Number GO6-17100X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060.
Publisher Copyright:
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2018/6/11
Y1 - 2018/6/11
N2 - Most active galactic nuclei (AGNs) are radio quiet, and the origin of their radio emission is not well understood. One hypothesis is that this radio emission is a byproduct of quasardriven winds. In this paper, we present the radio properties of 108 extremely red quasars (ERQs) at z = 2-4. ERQs are among the most luminous quasars (Lbol ~ 1047-48 erg s-1) in the Universe, with signatures of extreme (≫1000 km s-1) outflows in their [OIII]λ5007Å emission, making them the best subjects to seek the connection between radio and outflow activities. All ERQs but one are unresolved in the radio on ~10 kpc scales, and the median radio luminosity of ERQs is vLv[6 GHz] = 1041.0 erg s-1, in the radio-quiet regime, but 1-2 orders of magnitude higher than that of other quasar samples. The radio spectra are steep, with a mean spectral index 〈α〉 = -1.0. In addition, ERQs neatly follow the extrapolation of the low-redshift correlation between radio luminosity and the velocity dispersion of [O III]- emitting ionized gas. Uncollimated winds, with a power of one per cent of the bolometric luminosity, can account for all these observations. Such winds would interact with and shock the gas around the quasar and in the host galaxy, resulting in acceleration of relativistic particles and the consequent synchrotron emission observed in the radio. Our observations support the picture in which ERQs are signposts of extremely powerful episodes of quasar feedback, and quasar-driven winds as a contributor of the radio emission in the intermediate regime of radio luminosity vLv = 1039-1042 erg s-1.
AB - Most active galactic nuclei (AGNs) are radio quiet, and the origin of their radio emission is not well understood. One hypothesis is that this radio emission is a byproduct of quasardriven winds. In this paper, we present the radio properties of 108 extremely red quasars (ERQs) at z = 2-4. ERQs are among the most luminous quasars (Lbol ~ 1047-48 erg s-1) in the Universe, with signatures of extreme (≫1000 km s-1) outflows in their [OIII]λ5007Å emission, making them the best subjects to seek the connection between radio and outflow activities. All ERQs but one are unresolved in the radio on ~10 kpc scales, and the median radio luminosity of ERQs is vLv[6 GHz] = 1041.0 erg s-1, in the radio-quiet regime, but 1-2 orders of magnitude higher than that of other quasar samples. The radio spectra are steep, with a mean spectral index 〈α〉 = -1.0. In addition, ERQs neatly follow the extrapolation of the low-redshift correlation between radio luminosity and the velocity dispersion of [O III]- emitting ionized gas. Uncollimated winds, with a power of one per cent of the bolometric luminosity, can account for all these observations. Such winds would interact with and shock the gas around the quasar and in the host galaxy, resulting in acceleration of relativistic particles and the consequent synchrotron emission observed in the radio. Our observations support the picture in which ERQs are signposts of extremely powerful episodes of quasar feedback, and quasar-driven winds as a contributor of the radio emission in the intermediate regime of radio luminosity vLv = 1039-1042 erg s-1.
KW - Galaxies: Active
KW - Quasars: General
KW - Radio continuum: Galaxies
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U2 - 10.1093/mnras/sty742
DO - 10.1093/mnras/sty742
M3 - Article
AN - SCOPUS:85046665428
SN - 0035-8711
VL - 477
SP - 830
EP - 844
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -