Atomic and molecular gas in IllustrisTNG galaxies at low redshift

Benedikt Diemer, Adam R. H. Stevens, Claudia del P. Lagos, A. R. Calette, Sandro Tacchella, Lars Hernquist, Federico Marinacci, Dylan Nelson, Annalisa Pillepich, Vicente Rodriguez-Gomez, Francisco Villaescusa-Navarro, Mark Vogelsberger

Research output: Contribution to journalArticlepeer-review

44 Citations (Web of Science)


We have recently developed a post-processing framework to estimate the abundance of atomic and molecular hydrogen (H I and H-2, respectively) in galaxies in large-volume cosmological simulations. Here we compare the HI and H-2 content of IllustrisTNG galaxies to observations. We mostly restrict this comparison to z approximate to 0 and consider six observational metrics: the overall abundance of HI and H-2, their mass functions, gas fractions as a function of stellar mass, the correlation between H-2 and star formation rate, the spatial distribution of gas, and the correlation between gas content and morphology. We find generally good agreement between simulations and observations, particularly for the gas fractions and the HI mass-size relation. The H-2 mass correlates with star formation rate as expected, revealing an almost constant depletion time that evolves up to z = 2 as observed. However, we also discover a number of tensions with varying degrees of significance, including an overestimate of the total neutral gas abundance at z = 0 by about a factor of 2 and a possible excess of satellites with no or very little neutral gas. These conclusions are robust to the modelling of the HI/H-2 transition. In terms of their neutral gas properties, the IllustrisTNG simulations represent an enormous improvement over the original Illustris run. All data used in this paper are publicly available as part of the IllustrisTNG data release.

Original languageEnglish
Pages (from-to)1529-1550
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - Aug 2019


Dive into the research topics of 'Atomic and molecular gas in IllustrisTNG galaxies at low redshift'. Together they form a unique fingerprint.

Cite this