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

Philip Mocz , Anastasia Fialkov , Mark Vogelsberger , Fernando Becerra , Xuejian Shen , Victor H. Robles , Mustafa A. Amin , Jesús Zavala , Michael Boylan-Kolchin , Sownak Bose , Federico Marinacci , Pierre-Henri Chavanis (1, 2) , Lachlan Lancaster , Lars Hernquist

1 LPT - Laboratoire de Physique Théorique
2 PhyStat - Physique Statistique des Systèmes Complexes (LPT)

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 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.

Mots clés: galaxies: formation; galaxies: high-redshift; dark matter; cosmology: theory; star: formation; galaxy: formation; dark matter: power spectrum; dark matter: fuzzy; gravitation: coupling; potential: quantum; redshift: high; boson: mass; suppression; structure; Bose-Einstein; interference; signature; feedback; baryon; metal; dark matter: halo

Domaines: Astrophysique [astro-ph]; Relativité Générale et Cosmologie Quantique [gr-qc]

Philip Mocz, Anastasia Fialkov, Mark Vogelsberger, Fernando Becerra, Xuejian Shen, et al.. Galaxy formation with BECDM – II. Cosmic filaments and first galaxies. Monthly Notices of the Royal Astronomical Society, 2020, 494 (2), pp.2027-2044. ⟨10.1093/mnras/staa738⟩. ⟨hal-02459834⟩