SHELS: OPTICAL SPECTRAL PROPERTIES OF WISE 22μm SELECTED GALAXIES

We use a dense, complete redshift survey, the Smithsonian Hectospec Lensing Survey (SHELS), covering a 4 deg(2) region of a deep imaging survey, the Deep Lens Survey (DLS), to study the optical spectral properties of Wide-field Infrared Survey Explorer (WISE) 22 mu m selected galaxies. Among 507 WISE 22 mu m selected sources with (S/N)(22 mu m) >= 3 (approximate to S-22 mu m greater than or similar to 2.5 mJy), we identify the optical counterparts of 481 sources (similar to 98%) at R < 25.2 in the very deep, DLS R-band source catalog. Among them, 337 galaxies at R < 21 have SHELS spectroscopic data. Most of these objects are at z < 0.8. The infrared (IR) luminosities are in the range 4.5 x 10(8)(L-circle dot) less than or similar to L-IR less than or similar to 5.4 x 10(12)(L-circle dot). Most 22 mu m selected galaxies are dusty star-forming galaxies with a small (<1.5) 4000 angstrom break. The stacked spectra of the 22 mu m selected galaxies binned in IR luminosity show that the strength of the [O III] line relative to H beta grows with increasing IR luminosity. The optical spectra of the 22 mu m selected galaxies also show that there are some (similar to 2.8%) unusual galaxies with very strong [Ne III] lambda 3869, 3968 emission lines that require hard ionizing radiation such as active galactic nuclei (AGNs) or extremely young massive stars. The specific star formation rates (sSFRs) derived from the 3.6 and 22 mu m flux densities are enhanced if the 22 mu m selected galaxies have close late-type neighbors. The sSFR distribution of the 22 mu m selected galaxies containing AGNs is similar to the distribution for star-forming galaxies without AGNs. We identify 48 dust-obscured galaxy candidates with large (greater than or similar to 1000) mid-IR to optical flux density ratio. The combination of deep photometric and spectroscopic data with WISE data suggests that WISE can probe the universe to z similar to 2.