Herschel Survey of the Palomar-Green QSOs at Low Redshift
We investigate the global cold dust properties of 85 nearby (z ⩽ 0.5) QSOs, chosen from the Palomar-Green sample of optically luminous quasars. We determine their infrared spectral energy distributions and estimate their rest-frame luminosities by combining Herschel data from 70 to 500 μm with near-infrared and mid-infrared measurements from the 2MASS and the Wide-Field Infrared Survey Explorer. In most sources the far-infrared (FIR) emission can be attributed to thermally heated dust. Single temperature modified blackbody fits to the FIR photometry give an average dust temperature for the sample of 33 K, with a standard deviation of 8 K, and an average dust mass of 7 x 10^6 M⊙ with a standard deviation of 9 x 10^6 M⊙. Estimates of star formation rates that are based on the FIR continuum emission correlate with those based on the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature, however, the star formation rates estimated from the FIR continuum are higher than those estimated from the 11.3 μm PAH emission. We attribute this result to a variety of factors including the possible destruction of the PAHs and that, in some sources, a fraction of the FIR originates from dust heated by the active galactic nucleus and by old stars.
© 2015 The American Astronomical Society. Received 2014 December 30; accepted 2015 May 13; published 2015 August 6. L.C.H. acknowledges support by the Chinese Academy of Science through grant No. XDB09030102 (Emergence of Cosmological Structures) from the Strategic Priority Research Program and by the National Natural Science Foundation of China through grant No. 11473002. We thank the anonymous referee for providing valuable comments and help in improving the contents of this paper. This publication makes use of data products from the 2MASS, 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. The authors would like to thank Nicolas Billot for help preparing the observations, and Roberta Paladini for numerous and very helpful consultations about Herschel data reduction and HIPE. A.P. would like to thank Mia U. and Maya Angelou for their lives and words "You may encounter many defeats, but you must not be defeated. In fact, it may be necessary to encounter the defeats, so you can know who you are, what you can rise from, how you can still come out of it" (M.A.).
Submitted - 1505.05273v1.pdf
Published - Petric_2015.pdf