A complete flux-limited sample of 50 galaxies is presented having f _ { \nu } ( 24 \mu m ) > 10 mJy , chosen from a survey with the Multiband Imaging Photometer on Spitzer ( MIPS ) of 8.2 deg ^ { 2 } within the NOAO Deep Wide-Field Survey region in Bootes ( NDWFS ) .
Spectra obtained with the low-resolution modules of the Infrared Spectrograph on Spitzer ( IRS ) are described for 36 galaxies within this sample ; 25 show strong PAH emission features characteristic of starbursts , and 11 show silicate absorption or emission , emission lines , or featureless spectra characteristic of AGN .
Infrared or optical spectral classifications are available for 48 of the entire sample of 50 ; 33 galaxies are classified as starbursts and 15 as AGN .
( There are an additional 19 Galactic stars with f _ { \nu } ( 24 \mu m ) > 10 mJy in the survey area . )
Using a relation between 7.7 \mu m PAH luminosity and star formation rate derived from previous IRS observations of starbursts , the star formation rate per unit volume of the local universe ( SFRD ) is determined from the complete sample and is found to be 0.008 M _ { \odot } yr ^ { -1 } Mpc ^ { -3 } .
This provides an extinction-free measurement of SFRD independent of optical properties and provides a parameter that can be used for direct comparison to high-redshift starbursts being discovered with Spitzer .
Individual sources in the sample have star formation rates from 0.14 to 160 M _ { \odot } yr ^ { -1 } .
The derived value for the local SFRD is about half that of the local SFRD deduced from bolometric luminosities of the IRAS 60 \mu m Bright Galaxy Sample , with the deficiency being at lower luminosities and arising primarily from the small number of low luminosity sources in the 10 mJy sample .
The agreement for higher luminosities confirms the validity of using the 7.7 \mu m PAH feature as a measure of SFRD in the high redshift universe , where this is often the only indicator available for faint sources .