[Picture credit: Suvendra Dutta] The closest void in our
galactic neighborhood is called the 'local void'. It is empty
except for a lonely dwarf galaxy whose velocity indicates it's
trying to move out of the void. That behavior is what one would
expect to happen to underdense regions during structure
formation. According to estimates following from ΛCDM
simulations one would also expect there to be about ten dwarf
galaxies in this void . So where are they? Why is the void so
empty? However, what is usually computed in structure formation
simulations is not the distribution of visible matter but that
of dark matter, and our usual matter follows the dark matter's
structures. Thus, what we actually know is that there are too
many dark matter dwarf haloes in the simulations as compared to
data. It might thus be the problem is not one with the void, but
that dark matter haloes just failed to form galaxies. ΛCDM also
predicts too many dwarf dark matter haloes as compared with the
observed dwarf galaxies . The solut