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Durham University

Department of Physics

Staff profile

Publication details for Prof David Alexander

Jarvis, M E, Harrison, C M, Thomson, A P, Circosta, C, Mainieri, V, Alexander, D M, Edge, A C, Lansbury, G B, Molyneux, S J & Mullaney, J R (2019). Prevalence of radio jets associated with galactic outflows and feedback from quasars. Monthly Notices of the Royal Astronomical Society 485(2): 2710-2730.

Author(s) from Durham

Abstract

We present 1–7 GHz high-resolution radio imaging (VLA and e-MERLIN) and spatially
resolved ionized gas kinematics for 10 z < 0.2 type 2 ‘obscured’ quasars (log [LAGN/erg s−1]
 45) with moderate radio luminosities (log[L1.4 GHz/W Hz−1] = 23.3–24.4). These targets
were selected to have known ionized outflows based on broad [O III] emission-line components
(full width at half-maximum≈800–1800 km s−1). Although ‘radio-quiet’ and not ‘radioAGN’
by many traditional criteria, we show that for nine of the targets, star formation likely accounts
for 10 per cent of the radio emission. We find that ∼80–90 per cent of these nine targets
exhibit extended radio structures on 1–25 kpc scales. The quasars’ radiomorphologies, spectral
indices, and position on the radio size–luminosity relationship reveals that these sources are
consistent with being low power compact radio galaxies. Therefore, we favour radio jets as
dominating the radio emission in the majority of these quasars. The radio jets we observe are
associated with morphologically and kinematically distinct features in the ionized gas, such as
increased turbulence and outflowing bubbles, revealing jet–gas interaction on galactic scales.
Importantly, such conclusions could not have been drawn from current low-resolution radio
surveys such as FIRST. Our observations support a scenario where compact radio jets, with
modest radio luminosities, are a crucial feedback mechanism for massive galaxies during a
quasar phase.