A Closer View of the Radio-FIR Correlation: Disentangling the Contributions of Star Formation and Active Galactic Nucleus Activity

Scientific paper - Original scientific paper

• Author: I. Morić
• Author: Vernesa Smolčić
• Author: A. Kimball
• Author: D. A. Riechers
• Author: Ž. Ivezić
• Author: N. Scoville
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

We extend the Unified Radio Catalog, a catalog of sources detected by various (NVSS, FIRST, WENSS, GB6) radio surveys, and SDSS, to IR wavelengths by matching it to the IRAS Point and Faint Source catalogs. By fitting each NVSS-selected galaxy's NUV-NIR spectral energy distribution (SED) with stellar population synthesis models we add to the catalog star formation rates (SFRs), stellar masses, and attenuations. We further add information about optical emission-line properties for NVSS-selected galaxies with available SDSS spectroscopy. Using an NVSS 20 cm (F_(1.4 GHz) ≳ 2.5 mJy) selected sample, matched to the SDSS spectroscopic ("main" galaxy and quasar) catalogs and IRAS data (0.04 < z ≲ 0.2) we perform an in-depth analysis of the radio-FIR correlation for various types of galaxies, separated into (1) quasars, (2) star-forming, (3) composite, (4) Seyfert, (5) LINER, and (6) absorption line galaxies using the standard optical spectroscopic diagnostic tools. We utilize SED-based SFRs to independently quantify the source of radio and FIR emission in our galaxies. Our results show that Seyfert galaxies have FIR/radio ratios lower than, but still within the scatter of, the canonical value due to an additional (likely active galactic nucleus (AGN)) contribution to their radio continuum emission. Furthermore, IR-detected absorption and LINER galaxies are on average strongly dominated by AGN activity in both their FIR and radio emission; however their average FIR/radio ratio is consistent with that expected for star-forming galaxies. In summary, we find that most AGN-containing galaxies in our NVSS-IRAS-SDSS sample have FIR/radio flux ratios indistinguishable from those of the star-forming galaxies that define the radio-FIR correlation. Thus, attempts to separate AGNs from star-forming galaxies by their FIR/radio flux ratios alone can separate only a small fraction of the AGNs, such as the radio-loud quasars.

• Keywords (english): cosmology: observations; evolution; galaxies: active; galaxies: fundamental parameters; radio continuum: galaxies
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Astrophysical Journal
• Numbering: vol. 724, no. 1, pp. 779-790
• p-ISSN: 0004-637X
• e-ISSN: 1538-4357
• DOI: https://doi.org/10.1088/0004-637X/724/1/779
• URN:NBN: urn:nbn:hr:217:660581
• Publication: 2010
• Document URL: http://dx.doi.org/10.1088/0004-637X/724/1/779
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2010 American Astronomical Society. Received 2010 August 9; accepted 2010 September 21; published 2010 November 4.
• Created on: 2019-11-01 19:18:16