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Galaxy Cold Gas Contents in Modern Cosmological Hydrodynamic Simulations

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  • Romeel Davé
  • Robert A. Crain
  • Adam R. H. Stevens
  • Desika Narayanan
  • Amelie Saintonge
  • Barbara Catinella
  • Luca Cortese

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Original languageEnglish
Pages (from-to)146-166
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume497
Issue number1
Early online date3 Jul 2020
DOIs
Publication statusPublished - 1 Sep 2020

Abstract

We present a comparison of galaxy atomic and molecular gas properties in three recent cosmological hydrodynamic simulations, Simba, EAGLE, and IllustrisTNG, versus observations from z 0 - 2. These simulations all rely on similar sub-resolution prescriptions to model cold interstellar gas which they cannot represent directly, and qualitatively reproduce the observed z 0 Hi and H2 mass functions (HIMF, H2MF), CO(1-0) luminosity functions (COLF), and gas scaling relations versus stellar mass, specific star formation rate, and stellar
surface density , with some quantitative differences. To compare to the COLF, we apply an H2-to-CO conversion factor to the simulated galaxies based on their average molecular surface density and metallicity, yielding substantial variations in CO and significant differences between models. Using this, predicted z = 0 COLFs agree better with data than predicted H2MFs. Out to z 2, EAGLE’s and Simba’s HIMF and COLF strongly increase, while IllustrisTNG’s HIMF declines and COLF evolves slowly. EAGLE and Simba reproduce high LCO1-0 galaxies at z 1 - 2 as observed, owing partly to a median CO¹z = 2º 1 versus CO¹z = 0º 3. Examining Hi, H2, and CO scaling relations, their trends with M are broadly
reproduced in all models, but EAGLE yields too little Hi in green valley galaxies, IllustrisTNG and Simba overproduce cold gas in massive galaxies, and Simba overproduces molecular gas in small systems. Using Simba variants that exclude individual AGN feedback modules, we find that Simba’s AGN jet feedback is primarily responsible by lowering cold gas contents from z 1 ! 0 by suppressing cold gas in M & 1010M galaxies, while X-ray feedback suppresses the formation of high- systems.

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  • astro-ph.GA

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