Realistic HI scale heights of Milky Way-mass galaxies in the FIREbox cosmological volume

Abstract

Accurately reproducing the thin cold gas discs observed in nearby spiral galaxies has been a long standing issue in cosmological simulations. Here, we present measurements of the radially resolved HI scale height in 22 non-interacting Milky Way-mass galaxies from the FIREbox cosmological volume. We measure the HI scale heights using five different approaches commonly used in the literature: fitting the vertical volume density distribution with a Gaussian, the distance between maximum and half-maximum of the vertical volume density distribution, a semi-empirical description using the velocity dispersion and the galactic gravitational potential, the analytic assumption of hydrostatic equilibrium, and the distance from the midplane which encloses $\gtrsim$60 per cent of the HI mass. We find median HI scale heights, measured using the vertical volume distribution, that range from ~100 pc in the galactic centres to ~800 pc in the outskirts and are in excellent agreement with recent observational results. We speculate that the presence of a realistic multiphase interstellar medium, including cold gas, and realistic stellar feedback are the drivers behind the realistic HI scale heights.

5 pages + appendix, 3 figures, updated to version accepted by MNRAS

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Cited by in corpus (6)

• FIREbox: Simulating galaxies at high dynamic range in a cosmological volume
• Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency
• The atomic-to-molecular hydrogen transition in the TNG50 simulation: Using realistic UV fields to create spatially resolved HI maps
• Synchrotron Emission on FIRE: Equipartition Estimators of Magnetic Fields in Simulated Galaxies with Spectrally-Resolved Cosmic Rays
• HI within and around observed and simulated galaxy discs -- Comparing MeerKAT observations with mock data from TNG50 and FIRE-2
• Semi-empirical constraints on the HI mass function of star-forming galaxies and ${\Omega }_{\mathrm{HI}}$ at $z\sim 0.37$ from interferometric surveys