Hectospec and Hydra spectra of infrared luminous sources in the AKARI North Ecliptic Pole Survey field.
SHIM H., IM M., KO J., JEON Y., KAROUZOS M., KIM S.J., LEE H.M., PAPOVICH C., WILLMER C. and WEINER B.J.
Abstract (from CDS):
We present spectra of 1796 sources selected in the AKARI North Ecliptic Pole Wide Survey field, obtained with MMT/Hectospec and WIYN/Hydra, for which we measure 1645 redshifts. We complemented the generic flux-limited spectroscopic surveys at 11 µm and 15 µm, with additional sources selected based on the MIR and optical colors. In MMT/Hectospec observations, the redshift identification rates are ∼80% for objects with R < 21.5 mag. On the other hand, in WIYN/Hydra observations, the redshift identification rates are ∼80% at R magnitudes brighter than 19 mag. The observed spectra were classified through the visual inspection or from the line diagnostics. We identified 1128 star-forming or absorption-line-dominated galaxies, 198 Type-1 active galactic nuclei (AGNs), 8 Type-2 AGNs, 121 Galactic stars, and 190 spectra in unknown category due to low signal-to-noise ratio. The spectra were flux-calibrated but to an accuracy of 0.1-0.18 dex for most of the targets and worse for the remainder. We derive star formation rates (SFRs) from the mid-infrared fluxes or from the optical emission lines, showing that our sample spans an SFR range of 0.1 to a few hundred M☉/yr. We find that the extinction inferred from the difference between the IR and optical SFR increases as the IR luminosity increases but with a large scatter.