THE VLA-COSMOS PERSPECTIVE ON THE INFRARED-RADIO RELATION. I. NEW CONSTRAINTS ON SELECTION BIASES AND THE NON-EVOLUTION OF THE INFRARED/RADIO PROPERTIES OF STAR-FORMING AND ACTIVE GALACTIC NUCLEUS GALAXIES AT INTERMEDIATE AND HIGH REDSHIFT
- Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
- Spitzer Science Center, MC 314-6, California Institute of Technology, Pasadena, CA 91125 (United States)
- AIM Unite Mixte de Recherche CEA CNRS Universite Paris VII UMR n158 (France)
- CEA-Saclay, Service d'Astrophysique, F-91191 Gif-sur-Yvette (France)
- Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States)
- Department of Physics, ETH Zurich, CH-8093 Zurich (Switzerland)
- Max-Planck-Institut fuer Plasmaphysik, Boltzmanstrasse, D-85741 Garching (Germany)
- California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
- INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
- Max Planck Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei Muenchen (Germany)
- National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801-0387 (United States)
- Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, HI 96822 (United States)
- National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85726 (United States)
VLA 1.4 GHz ({sigma}{approx} 0.012 mJy) and MIPS 24 and 70 {mu}m ({sigma}{approx} 0.02 and 1.7 mJy, respectively) observations covering the 2 deg{sup 2} COSMOS field are combined with an extensive multiwavelength data set to study the evolution of the infrared (IR)-radio relation at intermediate and high redshift. With {approx}4500 sources-of which {approx}30% have spectroscopic redshifts-the current sample is significantly larger than previous ones used for the same purpose. Both monochromatic IR/radio flux ratios (q {sub 24} and q {sub 70}), as well as the ratio of the total IR and the 1.4 GHz luminosity (q {sub TIR}), are used as indicators for the IR/radio properties of star-forming galaxies and active galactic nuclei (AGNs). Using a sample jointly selected at IR and radio wavelengths in order to reduce selection biases, we provide firm support for previous findings that the IR-radio relation remains unchanged out to at least z{approx} 1.4. Moreover, based on data from {approx}150 objects we also find that the local relation likely still holds at zin [2.5, 5]. At redshift z< 1.4, we observe that radio-quiet AGNs populate the locus of the IR-radio relation in similar numbers as star-forming sources. In our analysis, we employ the methods of survival analysis in order to ensure a statistically sound treatment of flux limits arising from non-detections. We determine the observed shift in average IR/radio properties of IR- and radio-selected populations and show that it can reconcile apparently discrepant measurements presented in the literature. Finally, we also investigate variations of the IR/radio ratio with IR and radio luminosity and find that it hardly varies with IR luminosity but is a decreasing function of radio luminosity.
- OSTI ID:
- 21301290
- Journal Information:
- Astrophysical Journal, Supplement Series, Vol. 186, Issue 2; Other Information: DOI: 10.1088/0067-0049/186/2/341; Country of input: International Atomic Energy Agency (IAEA); ISSN 0067-0049
- Country of Publication:
- United States
- Language:
- English
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