X-ray nuclear activity in S^(4)G barred galaxies: no link between bar strength and co-occurrent supermassive black hole fueling



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Gil de Paz, Armando and otros, ... (2013) X-ray nuclear activity in S^(4)G barred galaxies: no link between bar strength and co-occurrent supermassive black hole fueling. Astrophysical journal, 776 (1). ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/776/1/50


Stellar bars can lead to gas inflow toward the center of a galaxy and stimulate nuclear star formation. However, there is no compelling evidence on whether they also feed a central supermassive black hole: by measuring the fractions of barred active and inactive galaxies, previous studies have yielded conflicting results. In this paper, we aim to understand the lack of observational evidence for bar-driven active galactic nucleus (AGN) activity by studying a sample of 41 nearby (d < 35 Mpc) barred galaxies from the Spitzer Survey for Stellar Structure in Galaxies. We use Chandra observations to measure nuclear 2-10 keV X-ray luminosities and estimate Eddington ratios, together with Spitzer 3.6 μm imaging to quantify the strength of the stellar bar in two independent ways: (1) from its structure, as traced by its ellipticity and boxiness, and (2) from its gravitational torque Q_b , taken as the maximum ratio of the tangential force to the mean background radial force. In this way, rather than discretizing the presence of both stellar bars and nuclear activity, we are able to account for the continuum of bar strengths and degrees of AGN activity. We find nuclear X-ray sources in 31 out of 41 galaxies with median X-ray luminosity and Eddington ratio of L_X = 4.3 × 10^38 erg s^–1 and L_bol/L_Edd = 6.9 × 10^–6, respectively, consistent with low-luminosity AGN activity. Including upper limits for those galaxies without nuclear detections, we find no significant correlation between any of the bar strength indicators and the degree of nuclear activity, irrespective of galaxy luminosity, stellar mass, Hubble type, or bulge size. Strong bars do not favor brighter or more efficient nuclear activity, implying that at least for the low-luminosity regime, supermassive black hole fueling is not closely connected to large-scale features.

Item Type:Article
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© 2013. The American Astronomical Society. All rights reserved. Artículo firmado por 26 autores. M.C. thanks Professor Ron Buta for providing morphological classifications for the sample, and the anonymous referee for useful suggestions. D. A. G. thanks Michael West for useful discussions. E. A. and A. B. acknowledge the CNES (Centre National d'Etudes Spatiales, France) for financial support. We 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. This work was co-funded under the Marie Curie Actions of the European Commission (FP7-COFUND). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research is based in part on observations made with the Spitzer Space Telescope, and makes use of the NASA/IPAC Extragalactic Database (NED), both of which are operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. We acknowledge the usage of the HyperLeda database (http://leda.univ-lyonl.fr). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

Uncontrolled Keywords:Central mass concentrations; Seyfert 2 galaxies; Stellar velocity dispersions; Space-telescope observations; Infrared surface photometry; Nearby spiral galaxies; Star-forming galaxies; AGN host galaxies; Similar-to 1; Galactic nuclei
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:35026
Deposited On:15 Jan 2016 13:04
Last Modified:10 Dec 2018 15:05

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