Locally Cold Flows from Large-Scale Structure
  We show that the "cold" Hubble flow observed for galaxies around the Milky
Way does not represent a problem in cosmology but is due to the particular
geometry and dynamics of our local wall. The behavior of the perturbed Hubble
flow around the Milky Way is the result of two main factors: at small scales (R
< 1 Mpc) the inflow is dominated by the gravitational influence of the Milky
Way. At large scales (R > 1 Mpc) the out flow reflects the expansion of our
local wall which "cools down" the peculiar velocities. This is an intrinsic
property of walls and is independent of cosmology. We find the dispersion of
the local Hubble flow (1 < R < 3 Mpc) around simulated "Milky Way" haloes
located at the centre of low-density cosmological walls to be {\sigma}_H ~ 30
km/s, in excellent agreement with observations. The expansion of our local wall
is also reflected in the value of the measured local Hubble constant. For
"Milky Way" haloes inside walls, we find super-Hubble flows with h_local \simeq
0.77 - 1.13. The radius of equilibrium (R_0) depends not only on the mass of
the central halo and the Hubble expansion but also on the dynamics given by the
local LSS geometry. The super-Hubble flow inside our local wall has the effect
of reducing the radius at which the local expansion balances the gravitational
influence of the Milky Way. By ignoring the dynamical effect of the local wall,
the mass of the Milky Way estimated from R_0 can be underestimated by as much
as ~ 30%.
