2005/09/30 by H. Wu, C. Cao, C. -N. Hao +5 · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1086/497961
published as Astrophys.J.632:L79-L82,2005 · 7 pages, 2 Postscript figures, published by ApJ Letter
arxiv created 2005/10/14 · arxiv updated 2009/12/01
We present evidence that the 8 μm (dust) and 24 μm luminosities of star-forming galaxies are both strongly correlated with their 1.4 GHz and Hα luminosities over a range in luminosity of two-to-three orders of magnitude. At the bright end, the correlations are found to be essentially linear over a luminosity range of about two orders of magnitude (corresponding to star-formation rates of several-tenths to several tens of solar masses per year). However, at the faint end, there appears to be a slope change for dwarf galaxies, possibly due to the lower dust-to-gas ratios and lower metallicities of the dwarfs. The correlations suggest that PAH features and mid-IR continuum emissions are good measures of the star formation rates of galaxies, and we present calibrations of star-formation rates based on existing radio and Hα relations. Our findings are based on a sample of star-forming galaxies selected from the main field of the Spitzer First Look Survey with the aid of spectroscopic data from the Sloan Digital Sky Survey and VLA 1.4 GHz data.