The bolocam 1.1 mm lockman hole galaxy survey: Sharc II 350 μm photometry and implications for spectral models, dust temperatures, and redshift estimation

We present 350 μm photometry of all 17 galaxy candidates in the Lockman Hole detected in a 1.1 mm Bolocam survey. Several of the galaxies were previously detected at 850 μm, at 1.2 mm, in the infrared by Spitzer, and in the radio. Nine of the Bolocam galaxy candidates were detected at 350 μm, and two new candidates were serendipitously detected at 350 μm (bringing the total in the literature detected in this way to three). Five of the galaxies have published spectroscopic redshifts, enabling investigation of the implied temperature ranges and a comparison of photometric redshift techniques. For z ≈ 2.5 thermally emitting galaxies, λ = 350 μm lies near the spectral energy distribution peak. Thus, luminosities can be measured without extrapolating to the peak from detection wavelengths of λ ≥ 850 μm. Characteristically, the galaxy luminosities lie in the range 1.0-1.2 × 10¹³ L_⊙, with dust temperatures in the range 40-70 K, depending on the choice of spectral index and wavelength of unit optical depth. The implied dust masses are (3-5) × 10⁸ M_⊙ We find that the far-infrared to radio relation for star-forming ULIRGs systematically overpredicts the radio luminosities and overestimates redshifts on the order of Δz ≈ s 1, whereas redshifts based on either submillimeter data alone or the 1.6 μm stellar bump and PAH features are more accurate.