Submillimetre flux as a probe of molecular ISM mass in high-z galaxies

Lichen Liang, Robert Feldmann, Claude-André Faucher-Giguère, Dušan Kereš, Philip F Hopkins, Christopher C Hayward, Eliot Quataert, Nick Z Scoville
2018 Monthly Notices of the Royal Astronomical Society: Letters  
Recent long wavelength observations on the thermal dust continuum suggest that the Rayleigh-Jeans (RJ) tail can be used as a time-efficient quantitative probe of the dust and ISM mass in high-z galaxies. We use high-resolution cosmological simulations from the Feedback in Realistic Environment (FIRE) project to analyze the dust emission of M_*>10^10 M_ galaxies at z=2-4. Our simulations (MassiveFIRE) explicitly include various forms of stellar feedback, and they produce the stellar masses and
more » ... ar formation rates of high-z galaxies in agreement with observations. Using radiative transfer modelling, we show that sub-millimeter (sub-mm) luminosity and molecular ISM mass are tightly correlated and that the overall normalization is in quantitative agreement with observations. Notably, sub-mm luminosity traces molecular ISM mass even during starburst episodes as dust mass and mass-weighted temperature evolve only moderately between z=4 and z=2, including during starbursts. Our finding supports the empirical approach of using broadband sub-mm flux as a proxy for molecular gas content in high-z galaxies. We thus expect single-band sub-mm observations with ALMA to dramatically increase the sample size of high-z galaxies with reliable ISM masses in the near future.
doi:10.1093/mnrasl/sly071 fatcat:zune3zjkmrco7ad2wijwxit5m4