TY - JOUR
T1 - On the Interpretation of Far-infrared Spectral Energy Distributions. I. the 850 μm Molecular Mass Estimator
AU - Privon, G. C.
AU - Narayanan, D.
AU - Davé, R.
N1 - Funding Information:
The authors thank the anonymous referee for his/her comments, which have improved the quality of the paper. The authors thank L. Armus, C. Cicone, A. Gowardhan, R. Feldmann, and L. Liang for comments on an earlier version of this paper. The authors thank M. Stalevski for information on the dust masses of AGN hosts and thank S. Linden for information on the clearing timescales for young star clusters. G.C.P. acknowledges support from the University of Florida and thanks the Sexten Center for Astrophysics(http://www. sexten-cfa.eu), where part of this work was performed. D.N. was funded in part by grants NSF AST-1715206 and HST AR-15043.0001. A portion of this work was performed at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611.
PY - 2018/11/10
Y1 - 2018/11/10
N2 - We use a suite of cosmological zoom galaxy formation simulations and dust radiative transfer calculations to explore the use of the monochromatic 850 μm luminosity (L ν,850) as a molecular gas mass (M mol) estimator in galaxies between 0 < z < 9.5 for a broad range of masses. For our fiducial simulations, where we assume that the dust mass is linearly related to the metal mass, we find that empirical L ν,850-M mol calibrations accurately recover the molecular gas mass of our model galaxies and that the L ν,850-dependent calibration is preferred. We argue that the major driver of scatter in the L ν,850-M mol relation arises from variations in the molecular gas-to-dust mass ratio, rather than variations in the dust temperature, in agreement with the previous study of Liang et al. Emulating a realistic measurement strategy with ALMA observing bands that are dependent on the source redshift, we find that estimating S ν,850 from continuum emission at a different frequency contributes 10%-20% scatter to the L ν,850-M mol relation. This additional scatter arises from a combination of mismatches in assumed T dust and β values, as well as the fact that the SEDs are not single-temperature blackbodies. However, this observationally induced scatter is a subdominant source of uncertainty. Finally, we explore the impact of a dust prescription in which the dust-to-metals ratio varies with metallicity. Though the resulting mean dust temperatures are ∼50% higher, the dust mass is significantly decreased for low-metallicity halos. As a result, the observationally calibrated L ν,850-M mol relation holds for massive galaxies, independent of the dust model, but below L ν,850 ≲ 1028 erg s-1 (metallicities ) we expect that galaxies may deviate from literature observational calibrations by 0.5 dex.
AB - We use a suite of cosmological zoom galaxy formation simulations and dust radiative transfer calculations to explore the use of the monochromatic 850 μm luminosity (L ν,850) as a molecular gas mass (M mol) estimator in galaxies between 0 < z < 9.5 for a broad range of masses. For our fiducial simulations, where we assume that the dust mass is linearly related to the metal mass, we find that empirical L ν,850-M mol calibrations accurately recover the molecular gas mass of our model galaxies and that the L ν,850-dependent calibration is preferred. We argue that the major driver of scatter in the L ν,850-M mol relation arises from variations in the molecular gas-to-dust mass ratio, rather than variations in the dust temperature, in agreement with the previous study of Liang et al. Emulating a realistic measurement strategy with ALMA observing bands that are dependent on the source redshift, we find that estimating S ν,850 from continuum emission at a different frequency contributes 10%-20% scatter to the L ν,850-M mol relation. This additional scatter arises from a combination of mismatches in assumed T dust and β values, as well as the fact that the SEDs are not single-temperature blackbodies. However, this observationally induced scatter is a subdominant source of uncertainty. Finally, we explore the impact of a dust prescription in which the dust-to-metals ratio varies with metallicity. Though the resulting mean dust temperatures are ∼50% higher, the dust mass is significantly decreased for low-metallicity halos. As a result, the observationally calibrated L ν,850-M mol relation holds for massive galaxies, independent of the dust model, but below L ν,850 ≲ 1028 erg s-1 (metallicities ) we expect that galaxies may deviate from literature observational calibrations by 0.5 dex.
KW - galaxies: ISM
KW - galaxies: evolution
KW - galaxies: high-redshift
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U2 - 10.3847/1538-4357/aae485
DO - 10.3847/1538-4357/aae485
M3 - Article
AN - SCOPUS:85056724584
VL - 867
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 102
ER -