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

M. T. Sargent, E. Schinnerer, E. Murphy, H. Aussel, E. Le Floc'H, D. T. Frayer, A. Martínez-Sansigre, P. Oesch, M. Salvato, V. Smolić, G. Zamorani, M. Brusa, Nico Cappelluti, C. L. Carilli, C. M. Carollo, O. Ilbert, J. Kartaltepe, A. M. Koekemoer, S. J. Lilly, D. B. SandersN. Z. Scoville

Research output: Contribution to journalReview article

72 Scopus citations

Abstract

VLA 1.4 GHz (σ 0.012 mJy) and MIPS 24 and 70μm (σ 0.02 and 1.7 mJy, respectively) observations covering the 2 deg2 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 4500 sources - of which 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 24 and q 70), as well as the ratio of the total IR and the 1.4 GHz luminosity (q 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 1.4. Moreover, based on data from 150 objects we also find that the local relation likely still holds at z∈ [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.

Original languageEnglish (US)
Pages (from-to)341-377
Number of pages37
JournalAstrophysical Journal, Supplement Series
Volume186
Issue number2
DOIs
StatePublished - Mar 12 2010
Externally publishedYes

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Keywords

  • Cosmology: observations
  • Galaxies: active
  • Galaxies: evolution
  • Galaxies: high-redshift
  • Infrared: galaxies
  • Radio continuum: galaxies
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Sargent, M. T., Schinnerer, E., Murphy, E., Aussel, H., Le Floc'H, E., Frayer, D. T., Martínez-Sansigre, A., Oesch, P., Salvato, M., Smolić, V., Zamorani, G., Brusa, M., Cappelluti, N., Carilli, C. L., Carollo, C. M., Ilbert, O., Kartaltepe, J., Koekemoer, A. M., Lilly, S. J., ... Scoville, N. Z. (2010). 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. Astrophysical Journal, Supplement Series, 186(2), 341-377. https://doi.org/10.1088/0067-0049/186/2/341