The formation of Milky Way-mass disk galaxies in the first 500 million
  years of a cold dark matter universe
  Whether among the myriad tiny proto-galaxies there exists a population with
similarities to present day galaxies is an open question. We show, using
BlueTides, the first hydrodynamic simulation large enough to resolve the
relevant scales, that the first massive galaxies to form are %in fact predicted
to have extensive rotationally-supported disks. Although their morphology
resembles in some ways Milky-way types seen at much lower redshifts, these
high-redshift galaxies are smaller, denser, and richer in gas than their low
redshift counterparts. From a kinematic analysis of a statistical sample of 216
galaxies at redshift $z=8-10$ we have found that disk galaxies make up 70\% of
the population of galaxies with stellar mass $10^{10} M_\odot$ or greater. Cold
Dark Matter cosmology therefore makes specific predictions for the population
of large galaxies 500 million years after the Big Bang. We argue that
wide-field satellite telescopes (e.g. WFIRST) will in the near future discover
these first massive disk galaxies. The simplicity of their structure and
formation history should make possible new tests of cosmology.
