The Inflationary Magnetogenesis Mechanism Of Cosmological Primordial Magnetic Fields And Effect On Gravitational Waves

Magnetic fields are found everywhere in the universe.A primordial magnetic field is a magnetic field that has existed in a form unaffected by subsequent cosmological and astrophysical processes from its creation until now.Observations show that the primordial magnetic field has a large coherence length,and that inflation provides a good mechanism for generating such a large-scale magnetic field,namely the inflationary magnetogenesis mechanism.The exponential expansion of the cosmic scale factor during inflation can stretch Fourier simple positive modes to very large scales,and these simple positive modes can be generated by quantum upsurges of the electromagnetic field at super horizon scales,which also evolve into classical perturbations as these modes evolve to super horizon scales.Moreover,any pre-existing charge density is diluted extremely fast due to the rapid expansion of the universe,so the universe in the inflationary phase has a low conductivity and is not a good conductor,there is no flux freeze effect that would limit the magnetic field production.However,there is a major problem with the inflationary magnetogenesis mechanism,the magnetic induction strength will be diluted rapidly with the burst expansion of the cosmic scale factor,which is rooted in the conformal invariance of the electromagnetic field evolution.Therefore,in order to obtain a strong magnetic field during the inflation,a mechanism for the destruction of the conformal invariance of the electromagnetic field action should be introduced,the modification of the electromagnetic field action.In this thesis,based on the derivation of the usual inflationary magnetogenesis model of primordial magnetic fields,the inflationary magnetogenesis model with scalar mode non-uniform perturbation spatial and temporal background and the inflationary magnetogenesis model with multiple vector fields are investigated,and the influence of the inflationary magnetogenesis mechanism on the primordial gravitational wave generation is reviewed in the following three aspects:First,in this thesis,based on the usual inflationary magnetogenesis model of primordial magnetic fields,the inflationary magnetogenesis model in a non-uniform perturbed spatial and temporal context with scalar modes is investigated to break the conformal invariance of electromagnetic field evolution by introducing a coupling function.Unlike the usual models,Maxwell’s equations are derived in this thesis under the FRW metric with scalar perturbations.When scalar mode perturbations are considered,the form of the coupling function depends on the self-consistency of the action quantities.Therefore,this self-consistency can restrict the form of the coupling function.Further by giving the constraint equations of the coupling function,its specific form can be obtained.In calculating the power spectra of electric and magnetic fields,it is found that the coupling function increases with time during the slow rolling storm expansion period,which leads to strong coupling problems.Therefore,this problem is discussed qualitatively in this thesis by introducing a correction function during the reheating period.Second,in this thesis,the inflationary magnetogenesis model of primordial magnetic fields containing multiple vector fields is studied.Since a single coupling function cannot be both increasing and decreasing,the strong coupling and reaction problems cannot be avoided at the same time.Therefore,this thesis discusses the multiple vector fields stroboscopic magnetization model by introducing a coupling matrix between the stroboscopic and scalar fields in the multifield model instead of a single coupling function.In addition,three cases of double-field models and the effect of mutual-coupling between different vector fields are discussed in this thesis.Third,this thesis reviews the effects of several inflationary magnetgenesis mechanisms on primordial gravitational wave production,describes the general form of random gravitational wave evolution during inflation,and further compares the power spectrum of the model with the sensitivity of detector detection to discuss whether it can be detected in its detection range.