Galaxy Zoo: are bars responsible for the feeding of active galactic nuclei at 0.2 < z < 1.0

Edmond Cheung, Jonathan R. Trump, E. Athanassoula, Steven P. Bamford, Eric F. Bell, A. Bosma, Carolin N. Cardamone, Kevin R. V. Casteels, S. M. Faber, Jerome J. Fang, Lucy F. Fortson, Dale D. Kocevski, David C. Koo, Seppo Laine, Chris Lintott, Karen L. Masters, Thomas Melvin, Robert C. Nichol, Kevin Schawinski, Brooke SimmonsRebecca Smethurst, Kyle W. Willett

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We present a new study investigating whether active galactic nuclei (AGN) beyondthe local universe are preferentially fed via large-scale bars. Our investigation com-bines data from Chandra and Galaxy Zoo: Hubble (GZH) in the AEGIS, COSMOS,and GOODS-S surveys to create samples of face-on, disc galaxies at 0.2 < z < 1.0. Weuse a novel method to robustly compare a sample of 120 AGN host galaxies, definedto have 1042 erg s−1 < LX < 1044 erg s−1, with inactive control galaxies matched instellar mass, rest-frame colour, size, S´ersic index, and redshift. Using the GZH barclassifications of each sample, we demonstrate that AGN hosts show no statisticallysignificant enhancement in bar fraction or average bar likelihood compared to closely-matched inactive galaxies. In detail, we find that the AGN bar fraction cannot beenhanced above the control bar fraction by more than a factor of two, at 99.7% confidence. We similarly find no significant difference in the AGN fraction among barredand non-barred galaxies. Thus we find no compelling evidence that large-scale barsdirectly fuel AGN at 0.2 < z < 1.0. This result, coupled with previous results atz = 0, implies that moderate-luminosity AGN have not been preferentially fed bylarge-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 dominantfueling mechanism for supermassive black hole growth.
Original languageEnglish
Pages (from-to)505-516
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date18 Dec 2014
Publication statusPublished - 11 Feb 2015


  • astro-ph.GA
  • RCUK
  • STFC
  • ST/I001204/1

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