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Accretion Properties of High- and Low-Excitation Young Radio Galaxies
Journal article   Open access   Peer reviewed

Accretion Properties of High- and Low-Excitation Young Radio Galaxies

Donghoon Son, Jong-Hak Woo, Sang Chul Kim, Hai Fu, Nozomu Kawakatu, Vardha N Bennert, Tohru Nagao and Daeseong Park
The Astrophysical journal, Vol.757(2), pp.1-13
08/09/2012
DOI: 10.1088/0004-637X/757/2/140
url
https://doi.org/10.1088/0004-637X/757/2/140View
Published (Version of record) Open Access

Abstract

Young radio galaxies (YRGs) provide an ideal laboratory to explore the connection between accretion disk and radio jet thanks to their recent jet formation. We investigate the relationship between the emission-line properties, the black hole accretion rate, and the radio properties using a sample of 34 low-redshift (z < 0.4) YRGs. We classify YRGs as high-excitation galaxies (HEGs) and low-excitation galaxies (LEGs) based on the flux ratio of high-ionization to low-ionization emission lines. Using the H{\alpha} luminosities as a proxy of accretion rate, we find that HEGs in YRGs have \sim1 dex higher Eddington ratios than LEGs in YRGs, suggesting that HEGs have higher mass accretion rate or higher radiative efficiency than LEGs. In agreement with previous studies, we find that the luminosities of emission lines, in particular H{\alpha}, are correlated with radio core luminosity, suggesting that accretion and young radio activities are fundamentally connected.

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