Title: A new astrophysical solution to the Too Big To Fail problem - Insights from the MoRIA simulations,
Abstract: We test whether advanced galaxy models and analysis techniques of simulations
can alleviate the Too Big To Fail problem (TBTF) for late-type galaxies, which
states that isolated dwarf galaxy kinematics imply that dwarfs live in
lower-mass halos than is expected in a {\Lambda}CDM universe. Furthermore, we
want to explain this apparent tension between theory and observations. To do
this, we use the MoRIA suite of dwarf galaxy simulations to investigate whether
observational effects are involved in TBTF for late-type field dwarf galaxies.
To this end, we create synthetic radio data cubes of the simulated MoRIA
galaxies and analyse their HI kinematics as if they were real, observed
galaxies. We find that for low-mass galaxies, the circular velocity profile
inferred from the HI kinematics often underestimates the true circular velocity
profile, as derived directly from the enclosed mass. Fitting the HI kinematics
of MoRIA dwarfs with a theoretical halo profile results in a systematic
underestimate of the mass of their host halos. We attribute this effect to the
fact that the interstellar medium of a low-mass late-type dwarf is continuously
stirred by supernova explosions into a vertically puffed-up, turbulent state to
the extent that the rotation velocity of the gas is simply no longer a good
tracer of the underlying gravitational force field. If this holds true for real
dwarf galaxies as well, it implies that they inhabit more massive dark matter
halos than would be inferred from their kinematics, solving TBTF for late-type
field dwarf galaxies.