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Published February 11, 2015 | Published + Submitted
Journal Article Open

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


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 10^(42) erg s^(−1) < LX < 10^(44) 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.

Additional Information

© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 November 20. Received 2014 November 13. In original form 2014 September 18. First published online December 18, 2014. 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. EC thanks Ramin A. Skibba, Michael Williams, Sugata Kaviraj, Yicheng Guo, Hassen Yesuf, and Guillermo Barro for useful discussions. The JavaScript Cosmology Calculator (Wright 2006) and TOPCAT (Taylor 2005) were used in the preparation of this paper. We also thank the anonymous referee for a helpful report.

Attached Files

Submitted - 1409.5434v2.pdf

Published - MNRAS-2015-Cheung-506-16.pdf


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August 20, 2023
August 20, 2023