Kavli Affiliate: George Efstathiou
| First 5 Authors: Tibor Dome, Anastasia Fialkov, Nina Sartorio, Philip Mocz,
| Summary:
On large cosmological scales, anisotropic gravitational collapse is manifest
in the dark cosmic web. Its statistical properties are little known for
alternative dark matter models such as fuzzy dark matter (FDM). In this work,
we assess for the first time the relative importance of cosmic nodes,
filaments, walls and voids in a cosmology with primordial small-scale
suppression of power. We post-process $N$-body simulations of FDM-like
cosmologies with varying axion mass $m$ at redshifts $zsim 1.0-5.6$ using the
NEXUS+ Multiscale Morphology Filter technique at smoothing scale $Delta x =
0.04 h^{-1}$Mpc. The formation of wall and void halos is more suppressed than
naively expected from the half-mode mass $M_{1/2}$. Also, we quantify the mass
and volume filling fraction of cosmic environments and find that 2D cosmic
sheets host a larger share of the matter content of the Universe as $m$ is
reduced, with an $sim 8-12$% increase for the $m=7 times 10^{-22}$ eV model
compared to CDM. We show that in FDM-like cosmologies, filaments, walls and
voids are cleaner and more pronounced structures than in CDM, revealed by a
strong mid-range peak in the conditioned overdensity PDFs $P(delta)$. At high
redshift, low-density regions are more suppressed than high-density regions.
Furthermore, skewness estimates $S_3$ of the total overdensity PDF in FDM-like
cosmologies are consistently higher than in CDM, especially at high redshift
$zsim 5.6$ where the $m=10^{-22}$ eV model differs from CDM by $sim 6
sigma$. Accordingly, we advocate for the usage of $P(delta)$ as a testbed for
constraining FDM and other alternative dark matter models.
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