Comparing properties of discs in Auriga to those in EAGLE and Illustris. (a) Resolution test for ℛ: the value of ℛ for the two lower resolution runs (Au17-5 and Au18-5) compared to the standard resolution runs (Au17-4 and Au18-4). For reference, we also show the mean and 2σ error of ℛ for the whole bar sample of Auriga, EAGLE, and Illustris. (b) Disc thickness: the flattening, ϵ = 1 − c/a, of disc galaxies in Auriga, Illustris, and EAGLE. The average values of the distributions (vertical dashed lines) are 0.42, 0.36, and 0.46, respectively. (c) Gas fraction vs. radius: the average gas density over stellar density in the Auriga galaxies as compared to disc galaxies in EAGLE and Illustris. (d) Gas fraction vs. normalised radius: as in panel c, with the radius normalised by the average bar length in each of the simulations.