Bibcode
Bahé, Y. M.; Crain, Robert A.; Kauffmann, Guinevere; Bower, Richard G.; Schaye, Joop; Furlong, Michelle; Lagos, Claudia; Schaller, Matthieu; Trayford, James W.; Dalla Vecchia, C.; Theuns, Tom
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 456, Issue 1, p.1115-1136
Advertised on:
2
2016
Citations
124
Refereed citations
122
Description
We compare the mass and internal distribution of atomic hydrogen (H I)
in 2200 present-day central galaxies with Mstar >
1010 M⊙ from the 100 Mpc EAGLE `Reference'
simulation to observational data. Atomic hydrogen fractions are
corrected for self-shielding using a fitting formula from radiative
transfer simulations and for the presence of molecular hydrogen using an
empirical or a theoretical prescription from the literature. The
resulting neutral hydrogen fractions, M_{H_I+H_2} / M_star, agree with
observations to better than 0.1 dex for galaxies with Mstar
between 1010 and 1011 M⊙. Our
fiducial, empirical H2 model based on gas pressure results in
galactic H I mass fractions, M_{H I/ M_star, that agree with
observations from the GASS survey to better than 0.3 dex, but the
alternative theoretical H2 formula from high-resolution
simulations leads to a negative offset in M_{H I}/ M_star of up to 0.5
dex. Visual inspection of mock H I images reveals that most H I discs in
simulated H I-rich galaxies are vertically disturbed, plausibly due to
recent accretion events. Many galaxies (up to 80 per cent) contain
spuriously large H I holes, which are likely formed as a consequence of
the feedback implementation in EAGLE. The H I mass-size relation of all
simulated galaxies is close to (but 16 per cent steeper than) observed,
and when only galaxies without large holes in the H I disc are
considered, the agreement becomes excellent (better than 0.1 dex). The
presence of large H I holes also makes the radial H I surface density
profiles somewhat too low in the centre, at Σ _{H I} > 1
M_{⊙} pc^{-2} (by a factor of ≲ 2 compared to data from the
Bluedisk survey). In the outer region (Σ _{H I} < 1 M_{⊙}
pc^{-2}), the simulated profiles agree quantitatively with observations.
Scaled by H I size, the simulated profiles of H I-rich (M_{H I}>
10^{9.8} M_{⊙}) and control galaxies (10^{9.1} M_{⊙}> M_{H I}
> 10^{9.8} M_{⊙}) follow each other closely, as observed.