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The Calibration of Star Formation Rate Indicators for WISE 22 Micron Selected Galaxies in the SDSS

We study star formation rate (SFR) indicators for Wide-field Infrared Survey Explorer (WISE) 22 μm selected, star-forming galaxies at 0.01 < z < 0.3 in the Sloan Digital Sky Survey. Using extinction-corrected Hα luminosities and total infrared luminosities as reference SFR estimates, we calibrate WISE mid-infrared (MIR) related SFR indicators. Both 12 and 22 μm monochromatic luminosities correlate well with the reference SFR estimates, but tend to underestimate SFRs of metal-poor galaxies (at lower than solar metallicity), consistent with previous studies. We mitigate this metallicity dependence using a linear combination of observed Hα and WISE MIR luminosities for SFR estimates. The combination provides robust SFR measurements as Kennicutt et al. (2009) applied to Spitzer data. However, we find that the coefficient a in L_Hα(obs) + a L_MIR increases with SFR, and show that a non-linear combination of observed Hα and MIR luminosities gives the best SFR estimates with small scatters and with little dependence on physical parameters. Such a combination of Hα and MIR luminosities for SFR estimates is first applied to WISE data. We provide several SFR recipes using WISE data applicable to galaxies with 0.1 <~ SFR (M_sun yr^-1) <~ 100.