Direct Evidence for Termination of Obscured Star Formation by Radiatively Driven Outflows in Reddened QSOs

Creators: Farrah, Duncan; Urrutia, Tanya; Lacy, Mark; Efstathiou, Andreas; Afonso, José; Coppin, Kristen; Hall, Patrick B.; Lonsdale, Carol; Jarrett, Tom; Bridge, Carrie; Borys, Colin; Petty, Sara M.

Abstract

We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from active galactic nuclei (AGNs) in their rest-frame UV spectra. We use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10^(12) L_☉ in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affected by the AGN-driven outflows. Conversely, we find an anticorrelation between the strength of AGN-driven outflows, as measured from the range of outflow velocities over which absorption exceeds a minimal threshold, and the contribution from star formation to the total IR luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows. Moreover, we find no convincing evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGNs can have a dramatic, negative impact on luminous star formation in their host galaxies. We find that such outflows act to curtail star formation such that star formation contributes less than ~25% of the total IR luminosity. We also propose that the degree to which termination of star formation takes place is not deducible from the IR luminosity of the AGN.

Additional Information

© 2012 American Astronomical Society. Received 2011 July 27; accepted 2011 December 4; published 2012 January 17. We thank the referee for a very helpful report, Sandra Blevins for help with reducing the Spitzer data, and Karen Leighly, Amanda Truitt, and Adrian Lucy for helpful comments. This work is based on observations made with the Spitzer Space Telescope, the Wide-field Infrared Survey Explorer (WISE), the Two Micron All Sky Survey (2MASS), and the Sloan Digital Sky Survey (SDSS). Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. WISE is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. 2MASS is a joint collaboration between the University of Massachusetts and the Infrared Processing and Analysis Center (JPL/Caltech), with funding provided primarily by NASA and the NSF. The SDSS and SDSS-II are funded by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is http://www.sdss.org/. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research has made extensive use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA, and of NASA's Astrophysics Data System. This research has also made use of Ned Wright's online cosmology calculator (Wright 2006). D.F. acknowledges support from the Science & Technology Facilities Council via an Advanced Fellowship (PP/E005306/1). J.A. acknowledges support from the Science and Technology Foundation (FCT, Portugal) through the research grant PTDC/CTE-AST/105287/2008. Facilities: Spitzer, WISE, 2MASS, Sloan, UKIRT

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