Jerome Quintin

Matter creation in a nonsingular bouncing cosmology

We examine reheating in the two-field matter bounce cosmology. In this model, the universe evolves from a matter-dominated phase of contraction to an Ekpyrotic phase of contraction before the nonsingular bounce. The Ekpyrotic phase frees the model from unwanted anisotropies, but leaves the universe cold and empty of particles after the bounce. For this reason, we explore two particle production mechanisms which take place during the course of the cosmological evolution: Parker particle production where the matter field couples only to gravity and particle creation via interactions between the matter field and the bounce field. Although we show that both mechanisms can produce particles in this model, we find that Parker particle production is sufficient to reheat the universe to high temperatures. Thus there is {\it{a priori}} no need to add an interaction term to the Lagrangian of the model. Still, particle creation via interactions can contribute to the formation of matter and radiation, but only if the coupling between the fields is tuned to be large.

Nonsingular bouncing cosmologies in light of BICEP2

We confront various nonsingular bouncing cosmologies with the recently released BICEP2 data and investigate the observational constraints on their parameter space. In particular, within the context of the effective field approach, we analyze the constraints on the matter bounce curvaton scenario with a light scalar field, and the new matter bounce cosmology model in which the universe successively experiences a period of matter contraction and an ekpyrotic phase. Additionally, we consider three nonsingular bouncing cosmologies obtained in the framework of modified gravity theories, namely the Hořava-Lifshitz bounce model, the f(T) bounce model, and loop quantum cosmology.

Evidence for interacting dark energy from BOSS

The result presented by the BOSS-SDSS Collaboration measuring the baryon acoustic oscillations of the Lyman-alpha forest from high-redshift quasars indicates a

Searching for features of a string-inspired inflationary model with cosmological observations

2.5\ensuremath{\sigma}

New model of axion monodromy inflation and its cosmological implications

departure from the standard

Cosmological perturbations and stability of nonsingular cosmologies with limiting curvature

\mathrm{\ensuremath{\Lambda}}

Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem

-cold-dark-matter model. This is the first time that the evolution of dark energy at high redshifts has been measured, and the current results cannot be explained by simple generalizations of the cosmological constant. We show here that a simple phenomenological interaction in the dark sector provides a good explanation for this deviation, naturally accommodating the Hubble parameter obtained by BOSS,

Evolution of Cataclysmic Variables and Related Binaries Containing a White Dwarf

H(z=2.34)=222\ifmmode\pm\else\textpm\fi{}7\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}

Cosmic string loops as the seeds of super-massive black holes

. By performing a global fit of the parameters with the inclusion of this new data set together with the Planck data for the interacting model, we are able to show that some interacting models have constraints for

Black hole formation in a contracting universe

H(2.34)