相关论文: Isocurvature Fluctuations Induce Early Star Format…

We investigate reheating of the universe by early formation of stars and quasars in the hierarchical clustering scheme of cold dark matter scenario, with perturbation fluctuations normalized by the COBE data. It is found that ionizing uv…

Recent observations have shown that the scatter in opacities among coeval segments of the Lyman-alpha forest increases rapidly at z > 5. In this paper, we assess whether the large scatter can be explained by fluctuations in the ionizing…

The standard structure formation scenario is successful on linear scales. Several apparent problems affect it however at galactic scales, such as the small scale problems at low redshift and more recent issues involving early massive galaxy…

The first galaxies formed at high redshifts, and were likely substantially less massive than typical galaxies in the local universe. We argue that (1) the reionization of a clumpy intergalactic medium by redshift z=6, (2) its enrichment by…

Axion-like dark matter whose symmetry breaking occurs after the end of inflation predicts enhanced primordial density fluctuations at small scales. This leads to dense axion minihalos (or miniclusters) forming early in the history of the…

Axions and axion-like particles (ALPs) have gained substantial attention as potential candidates for cold dark matter. The ALP field can exhibit fluctuations stemming from initial conditions. These initial field fluctuations hold the…

We summarize three recent efforts to constrain the first few moments of cosmic creation before and during the epoch of inflation. We consider two means to explain a slight dip in the power spectrum of the cosmic microwave background for…

The production of a stochastic background of relic gravitational waves is well known in various works in the literature, where, using the so called adiabatically-amplified zero-point fluctuations process it has been shown how the standard…

In the chaotic inflation models, quantum fluctuations for axion fields lead to the overproduction of domain walls and too large isocurvature fluctuations which is inconsistent with the observations of cosmic microwave background…

We describe an attempt to reconstruct the initial conditions for the formation of cosmological large-scale structure. The power spectrum of the primordial fluctuations is affected by bias, nonlinear evolution and redshift-space distortions,…

The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here…

We review why the search for a causal explanation of the large scale properties of the universe supports the idea that an extended period of accelerated expansion, called inflation, preceded primordial nucleosynthesis. As a consequence of…

It has recently been shown [1] that light vector particles produced from inflationary fluctuations can give rise to the dark matter in the Universe. A similar mechanism has been discussed in [2] for a non-minimally coupled scalar enjoying a…

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…

We present the results of a detailed study of how isocurvature axion fluctuations are converted into adiabatic metric perturbations through axion decay, and discuss the constraints on the parameters of pre-big bang cosmology needed for…

Large-scale polarization of the cosmic microwave background measured by the WMAP satellite requires a mean optical depth to Thomson scattering, tau_e ~ 0.17. The reionization of the universe must therefore have begun at relatively high…

The adiabatic index of a relativistic star (modeled by a perfect fluid) is shown to act as a dissipation constant due to considerations of mesoscopic scale stochastic effects. This dissipative effect arises without taking heat flux in the…

Star-forming galaxies in the early universe provide us with perhaps the most natural way of explaining the reionization of the universe. Current observational results are sufficiently comprehensive, as to allow us to approximately calculate…

Making use of the primordially isocurvature fluctuations, which are generated in inflationary models with multiple scalar fields, we make a phenomenological model that predicts formation of primordial black holes which can account for the…

We study thermally induced density perturbations during inflation. This scenario is characterized by two thermodynamical conditions: (1) The primordial perturbations originate in the epoch when the inflationary universe contains a…