3D-Herschel: Constraining Dust Emission with Panchromatic Modeling of 3D-HST Galaxies

We present 3D-Herschel, a new 0.3-350$μ$m photometric catalog that combines deblended Herschel far-infrared (FIR) imaging with the CANDELS/3D-HST legacy fields to probe the dust-obscured universe. Using the 17-parameter fitting code Prospector-$β$, a Bayesian inference framework, we model 41,387 galaxies spanning 0.5 $< z <$ 2.5 to measure stellar and dust properties with realistic error bars. Comparing fits with and without FIR constraints, we find that for the 3.2$\%$ of galaxies with $>3 σ$ detections in at least two Herschel bands, UV-MIR-only models (0.3-24$μ$m) recover robust stellar ages, SFRs, and stellar masses (50-70$\%$ within the median 1$σ$ error). Consequently, the star-forming sequence shows no systematic offset, with an average deviation of 0.1$\pm$0.07 dex at fixed stellar mass for FIR-detected sources at all redshifts. However, the use of rigid log-average IR templates with fixed dust emission parameters ($γ$, $U_{\mathrm{min}}$, $Q_{\mathrm{PAH}}$) in UV-MIR modeling corresponds to an unevolving MIR-to-IR luminosity ratio and cold dust temperatures. By contrast, fits that include Herschel photometry, with added freedom in the FIR, yield dust temperatures that are $\sim$7K warmer at all redshifts, with $\sim$0.2 dex higher IR-to-7.7$μ$m luminosity ratios at the low-mass end of a Herschel-detected sample (log($M_{\star}$) $\sim$9.6 $M_{\odot}$). These results demonstrate that MIR-to-IR conversions depend on stellar mass, cautioning against $L_{\mathrm{IR}}$-independent templates without FIR data. For galaxies with $<10^{11} \ M_{\odot}$ at $z>1.5$, even with state-of-the-art analysis, Herschel can at best provide upper limits due to source confusion; next-generation FIR telescopes will be essential to fully characterize dust emission in distant galaxies.