We present a new study investigating whether active galactic nuclei (AGN) beyond the local universe are preferentially fed via large-scale bars. Our investigation combines data from Chandra and Galaxy Zoo: Hubble (GZH) in the AEGIS (All-wavelength Extended Groth strip International Survey), COSMOS (Cosmological Evolution Survey), and (Great Observatories Origins Deep Survey-South) GOODS-S surveys to create samples of face-on, disc galaxies at 0.2 < z < 1.0. We use a novel method to robustly compare a sample of 120 AGN host galaxies, defined to have 1042 erg s−1 < LX < 1044 erg s−1, with inactive control galaxies matched in stellar mass, rest-frame colour, size, Sérsic index, and redshift. Using the GZH bar classifications of each sample, we demonstrate that AGN hosts show no statistically significant enhancement in bar fraction or average bar likelihood compared to closely-matched inactive galaxies. In detail, we find that the AGN bar fraction cannot be enhanced above the control bar fraction by more than a factor of 2, at 99.7 per cent confidence. We similarly find no significant difference in the AGN fraction among barred and non-barred galaxies. Thus we find no compelling evidence that large-scale bars directly fuel AGN at 0.2 < z < 1.0. This result, coupled with previous results at z = 0, implies that moderate-luminosity AGN have not been preferentially fed by large-scale bars since z = 1. Furthermore, given the low bar fractions at z > 1, our findings suggest that large-scale bars have likely never directly been a dominant fuelling mechanism for supermassive black hole growth.

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Notes/Citation Information

Published in Monthly Notices of the Royal Astronomical Society, v. 447, no. 1, p. 506-516.

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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Funding Information

Authors from UC Santa Cruz acknowledge financial support from the NSF Grant AST 08-08133. KS gratefully acknowledges support from Swiss National Science Foundation Grant PP00P2_138979/1. JRT acknowledges support by NASA through Hubble Fellowship grant HST-HF-51330.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. EA and AB acknowledge financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement number PITN-GA-2011-289313. They also acknowledge financial support from the CNES (Centre National d'Etudes Spatiales – France). RCN acknowledges STFC Rolling Grant ST/I001204/1 ‘Survey Cosmology and Astrophysics’. BS gratefully acknowledges support from the Oxford Martin School and from the Henry Skynner Junior Research Fellowship at Balliol College, Oxford. LFF and KWW acknowledge support from the UMN GIA programme.

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This publication has been made possible by the participation of more than 85,000 volunteers in the Galaxy Zoo project. Their contributions are individually acknowledged at http://authors.galaxyzoo.org/

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