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

Abstract

© 2020 Oxford University Press. All rights reserved. Bose-Einstein condensate darkmatter (BECDM,also known as fuzzy darkmatter) 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 ×10-22eV, exploring the dynamical effects of its wavelike nature on the cosmicweb and the formation of first galaxies.OurBECDMsimulations are directly compared toCDMaswell 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 ~ 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.