Related papers: Disformal transformations on the CMB
We consider the effect of modified gravity on the peak structure of the Cosmic Microwave Background (CMB) spectrum. We focus on simple models of modified gravity mediated by a massive scalar field coupled to both baryons and cold dark…
The analysis of anisotropies in the cosmic microwave background (CMB) has become an extremely valuable tool for cosmology. We even have hopes that planned CMB anisotropy experiments may revolutionize cosmology. Together with determinations…
It is well known that in manifestly Lorentz invariant theories with nontrivial kinetic terms, perturbations around some classical backgrounds can travel faster than light. These exotic "supersonic" models may have interesting consequences…
Accurate computations of spectral distortions of the cosmic microwave background (CMB) are required for constraining energy release scenarios at redshifts $z\gtrsim 10^3$. The existing literature focuses on distortions that are small…
We develop and examine the principles governing the formation of distortions in the cosmic microwave background. Distortions in the frequency or spectral distribution of the background probe the thermal history of the universe whereas those…
We investigate a statistical anisotropy on the Cosmic Microwave Background (CMB) bispectrum, which can be generated from the primordial non-Gaussianity induced by quantum fluctuations of a vector field. We find new configurations in the…
At the supranuclear densities achieved inside a neutron star, matter may exhibit extreme properties. In particular, it may be the case that a suitable average of the speed of sound squared exceeds the so-called conformal limit, i.e.,…
We exhibit a varying speed of light (VSL) theory that implements the recently proposed decaying speed of sound mechanism for generating density fluctuations. We avail ourselves of bimetric VSL theories, where the speed of gravity differs…
We consider a network of topological defects which can partly decay into neutrinos, photons, baryons, or Cold Dark Matter. We find that the degree-scale amplitude of the cosmic microwave background (CMB) anisotropies as well as the shape of…
We study the CMB constraints on two Dark Energy models described by scalar fields with different Lagrangians, namely a Klein-Gordon and a Born-Infeld field. The speed of sound of field fluctuations are different in these two theories, and…
We explore the effects of low-scale cosmological first-order phase transitions on Big Bang Nucleosynthesis (BBN) and Cosmic Microwave Background (CMB) anisotropy and distortion. We examine two scenarios: the distribution of the…
Non-linear evolution of cosmological energy density fluctuations triggers deviations from Gaussianity in the temperature distribution of the cosmic microwave background. A method to estimate these deviations is proposed. N-body simulations…
We study gravitational lensing statistics, matter power spectra and the angular power spectra of the cosmic microwave background (CMB) radiation in x-matter models. We adopt an equation-of-state of x-matter which can express a wide range of…
We analyse the dynamical properties of disformally transformed theories of gravity. We show that disformal transformation typically introduces novel degrees of freedom, equivalent to the mimetic dark matter, which possesses a Weyl-invariant…
By decomposing the damping tail of CMB anisotropies into a series of transfer functions representing individual physical effects, we provide ingredients that will aid in the reconstruction of the cosmological model from small-scale CMB…
We present an all-sky formalism for the Cosmic Microwave Background (CMB) bispectrum induced by the primordial non-Gaussianities not only in scalar but also in vector and tensor fluctuations. We find that the bispectrum can be formed in an…
The presence of cosmological perturbations affects the background metric and matter configuration in which the perturbations propagate. This effect, studied a long time ago for gravitational waves, also is operational for scalar…
We discuss a gauge invariant approach to the theory of cosmological perturbations in a higher-dimensonal background. We find the normal modes which diagonalize the perturbed action, for a scalar field minimally coupled to gravity, in a…
Gravitational potentials which change in time induce fluctuations in the observed cosmic microwave background (CMB) temperature. Cosmological structure moving transverse to our line of sight provides a specific example known as the moving…
The effect of gravitational lensing on cosmic microwave background (CMB) anisotropies is investigated using the power spectrum approach. The lensing effect can be calculated in any cosmological model by specifying the evolution of…