Calibration of Ultraviolet, Mid-infrared, and Radio Star Formation Rate Indicators

Abstract

We present calibrations for star formation rate (SFR) indicators in the ultraviolet, mid-infrared, and radiocontinuumbands, including one of the first direct calibrations of 150 MHz as an SFR indicator. Our calibrationsutilize 66 nearby star-forming galaxies with Balmer-decrement-corrected Ha luminosities, which span five ordersof magnitude in SFR and have absolute magnitudes of -24 < Mr < -12. Most of our photometry andspectrophotometry are measured from the same region of each galaxy, and our spectrophotometry has beenvalidated with SDSS photometry, so our random and systematic errors are small relative to the intrinsic scatter seenin SFR indicator calibrations. We find that the Wide-field Infrared Space Explorer W4 (22.8 µm), Spitzer 24 µm,and 1.4 GHz bands have tight correlations with the Balmer-decrement-corrected Ha luminosity, with a scatter ofonly 0.2 dex. Our calibrations are comparable to those from the prior literature for L* galaxies, but for dwarfgalaxies, our calibrations can give SFRs that are far greater than those derived from most previous literature.