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 in flow 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 } \sim 30 km s ^ { -1 } , 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 _ { \textrm { \tiny { 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 \sim 30 \% .