Calzetti, D. and Wu, S.-Y. and Hong, S. and Kennicutt, R. C. and Lee, J. C. and Dale, D. A. and Engelbracht, C. W. and van Zee, L. and Draine, B. T. and Hao, C.-N. and Gordon, K. D. and Moustakas, J. and Murphy, E. J. and Regan, M. and Begum, A. and Block, M. and Dalcanton, J. and Funes, J. and de Paz, A. Gil and Johnson, B. and Sakai, S. and Skillman, E. and Walter, F. and Weisz, D. and Williams, B. and Wu, Y. (2010) The calibration of monochromatic far-infrared star formation rate indicators. Astrophysical Journal, 714 (2). pp. 1256-1279. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100519-144150069
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Spitzer data at 24, 70, and 160 μm and ground-based Hα images are analyzed for a sample of 189 nearby star-forming and starburst galaxies to investigate whether reliable star formation rate (SFR) indicators can be defined using the monochromatic infrared dust emission centered at 70 and 160 μm. We compare recently published recipes for SFR measures using combinations of the 24 μm and observed Hα luminosities with those using 24 μm luminosity alone. From these comparisons, we derive a reference SFR indicator for use in our analysis. Linear correlations between SFR and the 70 μm and 160 μm luminosity are found for L(70) ≳ 1.4 × 10^(42) erg s^(–1) and L(160) ≳ 2 × 10^(42) erg s^(–1), corresponding to SFR ≳ 0.1-0.3 M_☉ yr^(–1), and calibrations of SFRs based on L(70) and L(160) are proposed. Below those two luminosity limits, the relation between SFR and 70 μm (160 μm) luminosity is nonlinear and SFR calibrations become problematic. A more important limitation is the dispersion of the data around the mean trend, which increases for increasing wavelength. The scatter of the 70 μm (160 μm) data around the mean is about 25% (factor ~2) larger than the scatter of the 24 μm data. We interpret this increasing dispersion as an effect of the increasing contribution to the infrared emission of dust heated by stellar populations not associated with the current star formation. Thus, the 70 (160) μm luminosity can be reliably used to trace SFRs in large galaxy samples, but will be of limited utility for individual objects, with the exception of infrared-dominated galaxies. The nonlinear relation between SFR and the 70 and 160 μm emission at faint galaxy luminosities suggests a variety of mechanisms affecting the infrared emission for decreasing luminosity, such as increasing transparency of the interstellar medium, decreasing effective dust temperature, and decreasing filling factor of star-forming regions across the galaxy. In all cases, the calibrations hold for galaxies with oxygen abundance higher than roughly 12 +log(O/H) ~ 8.1. At lower metallicity, the infrared luminosity no longer reliably traces the SFR because galaxies are less dusty and more transparent.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 August 3; accepted 2010 March 3; published 2010 April 19. This work is based in part 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. This work is part of LVL and SINGS, two of the Spitzer Space Telescope Legacy Science Programs; it has been partially supported by the JPL, Caltech, Contract Number 1316765. A.G.d.P. is partially financed by the Spanish Ram´on y Cajal program and the Programa Nacional de Astronoma y Astrofisica under grant AYA 2006-02358. C.-N. Hao acknowledges the support from NSFC key project 10833006. We thank an anonymous referee for many comments that have helped improve the manuscript. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.|
|Subject Keywords:||galaxies: interactions galaxies: ISM galaxies: starburst infrared: galaxies ISM: structure stars: formation|
|Classification Code:||PACS: 98.54.Ep; 98.62.Qz; 95.85.Gn; 98.62.Ai; 98.58.Jg; 98.58.Ca|
|Official Citation:||D. Calzetti et al 2010 ApJ 714 1256 doi: 10.1088/0004-637X/714/2/1256|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||20 May 2010 19:51|
|Last Modified:||26 Dec 2012 12:03|
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