A Caltech Library Service

Large amounts of optically obscured star formation in the host galaxies of some type 2 quasars

Lacy, M. and Sajina, A. and Petric, A. O. and Seymour, N. and Canalizo, G. and Ridgway, S. E. and Armus, L. and Storrie-Lombardi, L. J. (2007) Large amounts of optically obscured star formation in the host galaxies of some type 2 quasars. Astrophysical Journal Letters, 669 (2). L61-L64. ISSN 2041-8205. doi:10.1086/523851.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


We present Hubble Space Telescope images and spectral energy distributions from optical to infrared wavelengths for a sample of six type 2 quasars selected in the mid-infrared using data from the Spitzer 0.3 < z < 0.8 Space Telescope. All the host galaxies show some signs of disturbance. Most seem to possess dusty, star-forming disks. The disk inclination, estimated from the axial ratio of the hosts, correlates with the depth of the silicate feature in the mid-infrared spectra, implying that at least some of the reddening toward the AGN arises in the host galaxy. The star formation rates in these objects, as inferred from the strengths of the PAH features and far-infrared continuum, range from 3 to 90 M☉ yr^(-1), but are mostly much larger than those inferred from the M, [O II] λ3727 emission-line luminosity, due to obscuration. Taken together with studies of type 2 quasar hosts from samples selected in the optical and X-ray, this is consistent with previous suggestions that two types of extinction processes operate within the type 2 quasar population, namely, a component due to the dusty torus in the immediate environment of the AGN, and a more extended component due to a dusty, star-forming disk.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lacy, M.0000-0002-3032-1783
Sajina, A.0000-0002-1917-1200
Petric, A. O.0000-0003-4030-3455
Seymour, N.0000-0003-3506-5536
Canalizo, G.0000-0003-4693-6157
Armus, L.0000-0003-3498-2973
Storrie-Lombardi, L. J.0000-0002-5987-5210
Additional Information:© 2007 American Astronomical Society. Received 2007 August 1; accepted 2007 September 21; published 2007 October 12. We thank the referee for a helpful report. M.L. and A.O.P. were visiting astronomers at the IRTF, which is operated by the University of Hawaii under Cooperative Agreement NCC 5-538 with the National Aeronautics and Space Administration (NASA), Science Mission Directorate, Planetary Astronomy Program. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This work is also based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute (STScI), operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, and are associated with program 10848, partly supported by a grant from STScI.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASANAS 5-26555
Space Telescope Science InstituteUNSPECIFIED
Subject Keywords:galaxies: Seyfert; galaxies: starburst; infrared: galaxies; quasars: general
Issue or Number:2
Record Number:CaltechAUTHORS:LACapjl07
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12524
Deposited By: Tony Diaz
Deposited On:23 Dec 2008 23:44
Last Modified:08 Nov 2021 22:29

Repository Staff Only: item control page