Nonlinear clustering during the BEC dark matter phase transition

• Published in: The European physical journal. C, Particles and fields Vol. 75; no. 12; pp. 1 - 11
• Main Authors: de Freitas, Rodolfo C., Velten, Hermano
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2015; Springer; Springer Nature B.V
• Subjects: Analysis; Astronomy; Astrophysics and Cosmology; Collapse; Collapsing; Dark matter; Dark matter (Astronomy); Elementary Particles; Evolution; Hadrons; Heavy Ions; Mathematical analysis; Mathematical models; Measurement Science and Instrumentation; Nonlinearity; Nuclear Energy; Nuclear Physics; Numerical analysis; Phase transformations; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular Article - Theoretical Physics; String Theory; Dark Matter Density; Dark Matter Model; Dark Matter Particle; Cold Dark Matter; Dark Matter
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-015-3828-4

Spherical collapse of the Bose–Einstein condensate (BEC) dark matter model is studied in the Thomas–Fermi approximation. The evolution of the overdensity of the collapsed region and its expansion rate are calculated for two scenarios. We consider the case of a sharp phase transition (which happens when the critical temperature is reached) from the normal dark matter state to the condensate one and the case of a smooth first order phase transition where there is a continuous conversion of “normal” dark matter to the BEC phase. We present numerical results for the physics of the collapse for a wide range of the model’s space parameter, i.e. the mass of the scalar particle
m
χ
and the scattering length
l
s
. We show the dependence of the transition redshift on
m
χ
and
l
s
. Since small scales collapse earlier and eventually before the BEC phase transition, the evolution of collapsing halos in this limit is indeed the same in both the CDM and the BEC models. Differences are expected to appear only on the largest astrophysical scales. However, we argue that the BEC model is almost indistinguishable from the usual dark matter scenario concerning the evolution of nonlinear perturbations above typical clusters scales, i.e.,
≳
10
14
M
⊙
. This provides an analytical confirmation for recent results from cosmological numerical simulations (Schive et al., Nat Phys 10:496,
2014
).