Št. zadetkov: 39
Izvirni znanstveni članek
Oznake:
modified gravity;dark energy;cosmology;cosmological constraints;
We introduce mochi_class, an extension of the Einstein-Boltzmann solver hi_class, designed to unlock the full phenomenological potential of Horndeski gravity. This extension allows for general input functions of time without the need for hard-coded parametrisations or covariant Lagrangians. By repla ...
Leto:
2024
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
cosmology;Hubble parameter;age of the Universe;Bayesian methods;
We use recent measurements of the expansion history of the universe to place constraints on the parameter space of cubic Galileon models, in particular we concentrate on those models which contain the simplest Galileon term plus a linear potential. This gives strong constraints on the Lagrangian of ...
Leto:
2013
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;cosmological parameters from LSS;cosmological perturbation theory;dark energy theory;gravitation;effective field theory;
We present a turnkey solution, ready for implementation in numerical codes, for the study of linear structure formation in general scalar-tensor models involving a single universally coupled scalar field. We show that the totality of cosmological information on the gravitational sector can be compre ...
Leto:
2014
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;dark energy;cosmology;
We investigate the limits of applicability of the quasistatic approximation in cosmologies featuring
general models of dark energy or modified gravity. We show that, at best, the quasistatic approximation
breaks down outside of the sound horizon of the dark-energy, rather than the cosmological hor ...
Leto:
2015
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;dark energy;cosmology;power spectrum;
The scale of baryon acoustic oscillations (BAO) imprinted in the matter power spectrum provides an almost-perfect standard ruler: it only suffers subpercent deviations from fixed comoving length due to nonlinear effects. We study the BAO shift in the large Horndeski class of gravitational theories a ...
Leto:
2015
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;cosmological perturbation theory;dark energy theory;
In this paper we study the evolution of a spherical matter overdensity in the context of the recently introduced Galileon field theory. Our analysis considers the complete covariant Lagrangian in four dimensions. This theory is composed by a potential and a standard kinetic term, a cubic kinetic ter ...
Leto:
2012
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;power spectrum;non-gaussianity;dark energy;bispectrum;
We present a detailed study of second-order matter perturbations for the general Horndeski class of models. Being the most general scalar-tensor theory having second-order equations of motion, it includes many known gravity and dark energy theories and General Relativity with a cosmological constant ...
Leto:
2015
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;dark energy;cosmology;cosmological constraints;CMB, large-scale structure;power spectrum;perturbation theory;
Cosmological datasets have great potential to elucidate the nature of dark energy and test gravity on the largest scales available to observation. Theoretical predictions can be computed with hi_class (www.hiclass-code.net), an accurate, fast and flexible code for linear cosmology, incorporating a w ...
Leto:
2020
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;cosmological perturbations;
We study the phenomenology of the beyond Horndeski class of scalar-tensor theories of gravity, which on cosmological scales can be characterised in terms of one extra function of time, βH, as well as the usual four Horndeski set of free functions. We show that βH can be directly related to the dampi ...
Leto:
2019
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)
Izvirni znanstveni članek
Oznake:
modified gravity;Galileon;matter bispectrum;cosmological perturbations;
In this paper we obtain the bispectrum of dark matter density perturbations in the frame of covariant cubic Galileon theories. This result is obtained by means of a semi-analytic approach to second-order perturbations in Galileon cosmologies, assuming Gaussian initial conditions. In particular, we s ...
Leto:
2013
Vir:
Repozitorij Univerze v Novi Gorici (RUNG)