Galaxy Formation with BECDM -- II. Cosmic Filaments and First Galaxies
  Bose-Einstein Condensate Dark Matter (BECDM; also known as Fuzzy Dark Matter)
is motivated by fundamental physics and has recently received significant
attention as a serious alternative to the established Cold Dark Matter (CDM)
model. We perform cosmological simulations of BECDM gravitationally coupled to
baryons and investigate structure formation at high redshifts ($z \gtrsim 5$)
for a boson mass $m=2.5\cdot 10^{-22}~{\rm eV}$, exploring the dynamical
effects of its wavelike nature on the cosmic web and the formation of first
galaxies. Our BECDM simulations are directly compared to CDM as well as to
simulations where the dynamical quantum potential is ignored and only the
initial suppression of the power spectrum is considered -- a Warm Dark
Matter-like ("WDM") model often used as a proxy for BECDM. Our simulations
confirm that "WDM" is a good approximation to BECDM on large cosmological
scales even in the presence of the baryonic feedback. Similarities also exist
on small scales, with primordial star formation happening both in isolated
haloes and continuously along cosmic filaments; the latter effect is not
present in CDM. Global star formation and metal enrichment in these first
galaxies are delayed in BECDM/"WDM" compared to the CDM case: in BECDM/"WDM"
first stars form at $z\sim 13$/$13.5$ while in CDM star formation starts at
$z\sim 35$. The signature of BECDM interference, not present in "WDM", is seen
in the evolved dark matter power spectrum: although the small scale structure
is initially suppressed, power on kpc scales is added at lower redshifts. Our
simulations lay the groundwork for realistic simulations of galaxy formation in
BECDM.
