相关论文: Primordial Density Perturbations from Magnetic Fie…
A primordial magnetic field (PMF) can affect the evolution of density field fluctuations in the early universe.In this paper we constrain the PMF amplitude $B_\lambda$ and power spectral index $n_\mathrm{B}$ by comparing calculated density…
Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments…
Primordial magnetic fields generated in the early universe are subject of considerable investigation, and observational limits on their strength are required to constrain the theory. Due to their impact on the reionization process, the…
In this paper, we revisit in detail the effects of primordial magnetic fields on big bang nucleosynthesis (BBN) including a discussion of the magnetic field geometry and the anomalous magnetic moment. The presence of magnetic fields affects…
The primordial power spectrum of matter density perturbations contains highly valuable information about new fundamental physics, in particular cosmological inflation, but is only very weakly constrained observationally for small…
Weak magnetic fields must have existed in the early Universe, as they were sourced by the cross product of electron density and temperature gradients through the Biermann-battery mechanism. In this paper we calculate the magnetic fields…
Compensated isocurvature perturbations (CIPs) are perturbations to the primordial baryon density that are accompanied by dark-matter-density perturbations so that the total matter density is unperturbed. Such CIPs, which may arise in some…
Primordial magnetic fields could provide an explanation for the galactic magnetic fields observed today, in which case they may also leave interesting signals in the CMB and the small-scale matter power spectrum. We discuss how to…
In the pre-recombination era, cosmological density fluctuations can naturally generate magnetic fields through Thomson scatterings. In previous studies, only the magnetic field generation from the initially-adiabatic fluctuations has been…
Despite the ever growing observational evidence for the existence of the large scale magnetic fields, their origin and the evolution are not fully understood. If the magnetic fields are of primordial origin, they result in the generation of…
We study the second order scalar and density perturbations generated by the Gaussian curvature perturbations and primordial gravitational waves in the radiation-dominated era. After presenting all the possible second-order source terms, we…
The origin of interstellar and intergalactic magnetic fields remains largely unknown. One possibility is that they are related to the primordial magnetic fields (PMFs) produced by, for instance, the phase transitions of the early Universe.…
Primordial magnetic fields generated in the very early universe are one of the candidates for the origin of magnetic fields observed in galaxy clusters. After recombination, the Lorentz force acts on the residual ions and electrons to…
Magnetic fields appear to be present in all galaxies and galaxy clusters. Recent measurements indicate that a weak magnetic field may be present even in the smooth low density intergalactic medium. One explanation for these observations is…
Magnetic fields appear to be present in essentially all astrophysical environments, including galaxies, clusters of galaxies and voids. There are both observational and theoretical motives for considering the possibility of their origin…
We consider the presence and evolution of primordial density perturbations in a cosmological model based on a simple ansatz which captures -- by providing a set of effective gravitational field equations -- the strength of the enhanced…
Primordial magnetic fields (PMFs), which were generated in the early Universe before recombination, affect the motion of plasma and then the cosmic microwave background and the matter power spectrum. We consider constraints on PMFs with a…
From previous studies of the effect of primordial magnetic fields on early structure formation, we know that the presence of primordial magnetic fields during early structure formation could induce more perturbations at small scales (at…
The explanation of the observed galactic magnetic fields may require the existence of a primordial magnetic field. Such a field may arise during the early cosmological phase transitions, or because of other particle physics related…
Primordial magnetic fields (PMFs) offer a compelling explanation for the origin of observed magnetic fields, especially on extragalactic scales. Such PMFs give rise to excess of power in small scale matter perturbations that could strongly…