pop-cosmos: A Comprehensive Picture of the Galaxy Population from COSMOS Data
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We present pop-cosmos: a comprehensive model characterizing the galaxy population, calibrated to 140,938 (r < 25 selected) galaxies from the Cosmic Evolution Survey (COSMOS) with photometry in 26 bands from the ultraviolet to the infrared. We construct a detailed forward model for the COSMOS data, comprising: a population model describing the joint distribution of galaxy characteristics and its evolution (parameterized by a flexible score-based diffusion model); a state-of-the-art stellar population synthesis model connecting galaxies’ intrinsic properties to their photometry; and a data model for the observation, calibration, and selection processes. By minimizing the optimal transport distance between synthetic and real data, we are able to jointly fit the population and data models, leading to robustly calibrated population-level inferences that account for parameter degeneracies, photometric noise and calibration, and selection. We present a number of key predictions from our model of interest for cosmology and galaxy evolution, including the mass function and redshift distribution; the mass–metallicity-redshift and fundamental metallicity relations; the star-forming sequence; the relation between dust attenuation and stellar mass, star formation rate, and attenuation-law index; and the relation between gas-ionization and star formation. Our model encodes a comprehensive picture of galaxy evolution that faithfully predicts galaxy colors across a broad redshift (z < 4) and wavelength range.
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Acknowledgements: We thank George Efstathiou and Arthur Loureiro for useful discussions. J.A., S.T., S.D., and H.P. have been supported by funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programmes (grant agreement No. 101018897 CosmicExplorer). This work has been enabled by support from the research project grant “Understanding the Dynamic Universe” funded by the Knut and Alice Wallenberg Foundation under Dnr KAW 2018.0067. H.V.P. was additionally supported by the Göran Gustafsson Foundation for Research in Natural Sciences and Medicine. H.V.P. and D.M. acknowledge the hospitality of the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611. The participation of H.V.P. and D.M. at the Aspen Center for Physics was supported by the Simons Foundation. This research also utilized the Sunrise HPC facility supported by the Technical Division at the Department of Physics, Stockholm University. B.L. is supported by the Royal Society through a University Research Fellowship. This study utilizes observations collected at the European Southern Observatory under ESO program ID 179.A-2005 and 198.A-2003 and on data products produced by CALET and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium.
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1538-4365
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