Galaxy formation with BECDM – II. Cosmic filaments and first galaxies

Abstract

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 > ∼ 5) for a boson mass m = 2.5 · 10 −22 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 Matterlike ("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 ∼ 13/13.5 while in CDM star formation starts at z ∼ 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.

Beyond Schrödinger-Poisson: nonrelativistic effective field theory for scalar dark matter

“…The leading-order result in our EFT is consistent with the Schrödinger-Poisson (SP) system in an expanding universe, which is widely used in the literature [8]. For example, the SP system has enabled long-time-scale simulations of nonlinear structure formation of axion-like fields [14,31,32]. It has also been used to understand the cosmological formation, gravitational clustering, and scattering of solitons with strong self-interactions in the early and contemporary universe [16].…”

Wave turbulence in self-gravitating Bose gases and nonlocal nonlinear optics

“…(3) has only recently been investigated by direct numerical simulation in the cosmological setting [28] and appears to contain features of both the focusing and the defocusing nonlinear Schrödinger equation. As mentioned above, at large scales the Schrödinger-Newton model exhibits gravitationally driven accretion into filaments which then become unstable and collapse into spherical haloes [29,30] (cf. collapses in the focusing nonlinear Schrödinger model driven by the self-focusing local contact potential).…”

“…At large scales the two models become indistinguishable [18]. Thus, until the precise nature of dark matter particles is identified, fuzzy dark matter must be considered alongside cold dark matter when investigating the formation of large-scale structure in the early universe [18,[28][29][30].…”

To Observe, or Not to Observe, Quantum-Coherent Dark Matter in the Milky Way, That is a Question

“…Apart from the core-envelope structure of halos, some FDM simulations find large-scale coherence effects around and between halos (Schive et al, 2014a), (Mocz et al, 2017), extending all the way to cosmic filaments (Mocz et al, 2020), as well as finding signs of quantum turbulence within halo envelopes (Mocz et al, 2017). Unfortunately, current simulations cannot resolve the DM substructure expected in FDM and BEC-DM, in general.…”