Related papers: Delayed Recombination
Recent measurements of a peak in the angular power spectrum of the cosmic microwave background appear to suggest that geometry of the universe is close to being flat. But if other accepted indicators of cosmological parameters are also…
We fit the BOOMERANG, MAXIMA and COBE/DMR measurements of the cosmic microwave background anisotropy in spatially flat cosmological models where departures from standard recombination of the primeval plasma are parametrized through a change…
A key assumption of the standard cosmological model is that the temperature of the cosmic microwave background (CMB) radiation scales with cosmological redshift $z$ as $T_{\rm CMB}(z) \propto (1+z)$ at all times after recombination at…
The recombination of hydrogen and helium at z~1000-7000 gives unavoidable distortions to the Cosmic Microwave Background (CMB) spectrum. We present a detailed calculation of the line intensities arising from the Ly-alpha (2p-1s) and…
Minimal atomic dark matter with its distinctive cooling mechanisms offers an instructive framework for understanding the potential impact of dark matter on small-scale structure formation and early cosmology. The model consists of two…
The amplitude of the second peak in the angular power spectrum of the cosmic microwave background radiation is constrained to be small by recent experiments like Boomerang. This is surprising in the context of the LambdaCDM model, which…
The main goal of this work is to calculate the contributions to the cosmological recombination spectrum due to bound-bound transitions of helium. We show that due to the presence of helium in the early Universe unique features appear in the…
During cosmic recombination, charged particles bind into neutral atoms and the mean free path of photons rapidly increases, resulting in the familiar diffusion damping of primordial radiation temperature variations. An additional effect is…
One still cannot conclusively assert that the universe underwent a neutral phase, despite the new COBE FIRAS limit y<0.000025 on Compton y-distortions of the cosmic microwave background. Although scenarios where the very early (z=1000)…
We point out that polarization measurements as planned for the upcoming PLANCK mission can significantly enhance the accuracy of cosmic parameter estimation compared to the temperature anisotropy spectrum alone. In order to illustrate this,…
We examine cosmic microwave background constraints on variations in the recombination history of the universe. We use a very general extension to the standard model of recombination characterized by two parameters, a and b, which multiply…
The atomic recombination process leads to a softening of the matter equation of state as reflected by a reduced generalized adiabatic index, with accompanying heat release. We study the effects of this recombination softening and reheating…
The formation of the cosmic microwave background radiation (CMBR) provides a very powerful probe of the early universe at the epoch of recombination. Specifically, it is possible to constrain the variation of fundamental physical constants…
The Doppler peaks (Sacharov peaks) in the angular power spectrum of the cosmic microwave background anisotropies, are mainly due to coherent oscillations in the baryon radiation plasma before recombination. Here we present a calculation of…
A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios.…
Current cosmological constraints from Cosmic Microwave Background (CMB) anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing radiation sources can delay recombination,…
Light dark photons are subject to various plasma effects, such as Debye screening and resonant oscillations, which can lead to a more complex cosmological evolution than is experienced by conventional cold dark matter candidates.…
The non-linear evolution of the energy density of the radiation is shown to induce spectral distortions of the cosmic microwave background both at recombination and during the reionization era. This distortion has the same spectral…
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,…
Prior to the epoch of full reionization, the intergalactic medium and gravitationally collapsed systems will be detectable in 21-cm radiation. Physical mechanisms that would produce a 21-cm signature are discussed. These include Lya…