φ²as dark matter

Abstract

In this paper, we consider φ2 scalar field potential as a candidate to dark matter. If it is an ultralight boson particle, it condensates like a Bose–Einstein system at very early times and forms the basic structure of the Universe. Real scalar fields collapse in equilibrium configurations which oscillate in space–time (oscillatons).The cosmological behaviour of the field equations are solved using the dynamical system formalism. We use the current cosmological parameters as constraints for the present value of the scalar field and reproduce the cosmological predictions of the standard Λ cold dark matter model with this model. Therefore, scalar field dark matter seems to be a good alternative to cold dark matter nature.

Confusing the extragalactic neutrino flux limit with a neutrino propagation limit

“…It was shown in [50] that, for a coherent scalar field with a potential V (φ) ≃ φ k , the energy density decreases as ρ φ ∼ a −6k/(k+2) , with a the cosmic scale factor. For our case of interest of scalar field DM [27], the potential is V (φ) ∼ φ 2 and then, the energy density decreases as ρ φ ∼ a −3 , i.e., it evolves as dust and hence as cold dark matter.…”

“…DM scalar field candidates with mass in the range 10 −22 − 10 −24 eV have been proposed as viable DM particles [27,28,29,30,31,32]. Even lighter scalar fields, with masses lower than 10 −33 eV, have been postulated in order to explain DE [44,45,46,47].…”

“…Concerning ultra-light scalar fields as DM, they have been studied for a number of self-interaction potentials, like quadratic ones [27]. The main idea behind these models is that scalar fields were unified fields at a very early time after the origin of the universe.…”

“…A DM relic particle candidate must be non-relativistic, must be stable on the cosmological time scale, and must interact weakly with other particles. Some of the possible candidates are: WIMPS [16], axions [17,18,19,20,21], MeV-scalar fields [22,23], technicolor candidates [24,25,26], and ultra-light scalar fields [27,28,29,30,31,32]. An ultra-light scalar field is motivated as DM because it can alleviate some of the problems that arise at galactic scale in the standard paradigm of cold DM, namely, the origin of cuspy halos [33] and the overproduction of substructure [34].…”

A Review on the Scalar Field/Bose-Einstein Condensate Dark Matter Model

“…Different issues of the cosmological behavior of the SFDM/BEC model have been studied in a wide variety of approaches, see for example [80,3,55,60,118,75,77,106,107,114,50,52,81,6,82,26,120]. For example, [55] proposed fuzzy dark matter composed of ultra-light scalar particles initially in the form of a BEC.…”