SIMBAD references

In this paper, we present the measurements of the [N II] 205 µm line for a flux-limited sample of 122 (ultra-)luminous infrared galaxies [(U)LIRGs] and 20 additional normal galaxies, obtained with the Herschel Space Observatory (Herschel). We explore the far-infrared (FIR) color dependence of the [N II] 205 µm (L_[N II]205 µm_) to the total infrared (L_IR) luminosity ratio, and find that L_[N II]205 µm_/LIR_ only depends modestly on the 70-160 µm flux density ratio (f₇₀/f₁₆₀) when f₇₀/f₁₆₀≲0.6, whereas such dependence becomes much steeper for f₇₀/f₁₆₀> 0.6. We also investigate the relation between L_[N II]205 µm_ and star formation rate (SFR), and show that L_[N II]205 µm_ has a nearly linear correlation with SFR, albeit the intercept of such a relation varies somewhat with f₆₀/f₁₀₀, consistent with our previous conclusion that [N II] 205 µm emission can serve as an SFR indicator with an accuracy of ∼0.4 dex, or ∼0.2 dex if f₆₀/f₁₀₀ is known independently. Furthermore, together with the Infrared Space Observatory measurements of [N II], we use a total of ∼200 galaxies to derive the local [N II] 205 µm luminosity function (LF) by tying it to the known IR LF with a bivariate method. As a practical application, we also compute the local SFR volume density ({dot}ρ_SFR) using the newly derived SFR calibrator and LF. The resulting log {dot}ρ_SFR=-1.96±0.11M_☉ yr^–1 Mpc^–3 agrees well with previous studies. Finally, we determine the electron densities (n_e) of the ionized medium for a subsample of 12 (U)LIRGs with both [N II] 205 µm and [N II] 122 µm data, and find that n_e is in the range of ∼1-100 cm^–3, with a median value of 22 cm^–3.