Zobrazeno 1 - 10
of 69
pro vyhledávání: '"Sakr, Ziad"'
Autor:
Sakr, Ziad, Schey, Leonid
In this study, we incorporated a three-parameter family, of the metric incompatible modification of standard general relativity $f(Q)$ models into the Boltzmann code MGCLASS at both the background and perturbation levels, in order to conduct a Bayesi
Externí odkaz:
http://arxiv.org/abs/2405.03627
The ratio of Bayesian evidences is a popular tool in cosmology to compare different models. There are however several issues with this method: Bayes' ratio depends on the prior even in the limit of non-informative priors, and Jeffrey's scale, used to
Externí odkaz:
http://arxiv.org/abs/2404.00744
We show how one can test the cosmological Poisson equation by requiring only the validity of three main assumptions: the energy-momentum conservation equations of matter, the equivalence principle, and the cosmological principle. We first point out t
Externí odkaz:
http://arxiv.org/abs/2312.07436
Autor:
Sakr, Ziad, Carvalho, Ana, Da Silva, Antonio, Bellido, Juan Garcia, Mimoso, Jose P., Camarena, David, Nesseris, Savvas, Martins, Carlos J. A. P., Nunes, Nelson J., Sapone, Domenico
The Universe's assumed homogeneity and isotropy is known as the cosmological principle. It is one of the assumptions that lead to the Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) metric and it is a cornerstone of modern cosmology, because the metr
Externí odkaz:
http://arxiv.org/abs/2309.17151
Autor:
Sakr, Ziad
Models of dark energy or modified gravity that tries to alleviate the tensions on the Hubble constant ($H_0$) and the matter fluctuation parameter ($\sigma_8$) are usually parameterized as function of either late or early time cosmic evolution. In th
Externí odkaz:
http://arxiv.org/abs/2305.02913
Autor:
Sakr, Ziad
The matter fluctuation parameter $\sigma_8$ is, by model construction, degenerate with the growth index $\gamma$. Here, we study the effect on the cosmological parameter constraints by treating each independently from one another, considering $\sigma
Externí odkaz:
http://arxiv.org/abs/2305.02863
Autor:
Sakr, Ziad
We investigate whether the two cosmological discrepancies on the Hubble constant ($H_0$) and the matter fluctuation parameter ($\sigma_8$) are suggesting and compatible with the existence of an additional one on the matter density. Knowing that the l
Externí odkaz:
http://arxiv.org/abs/2305.02846
Autor:
Sakr, Ziad
We performed a Bayesian study on three beyond LCDM phenomenological triggering parameters, the growth index $\gamma$, the dark energy equation of state parameter $w$ and the lensing deviation from the GR prediction parameter $\Sigma$, using the lates
Externí odkaz:
http://arxiv.org/abs/2305.02817
Publikováno v:
Class. Quantum Grav. 39 184001 (2022)
The Universe may feature large-scale inhomogeneities beyond the standard paradigm, implying that statistical homogeneity and isotropy may be reached only on much larger scales than the usually assumed $\sim$100 Mpc. This means that we are not necessa
Externí odkaz:
http://arxiv.org/abs/2205.05422
Autor:
Sakr, Ziad, Martinelli, Matteo
In this paper we introduce a new public Einstein-Boltzmann solver, \texttt{MGCLASS II}, built as a modification to the publicly available \texttt{CLASS} code, that allows to obtain cosmological observables for Modified Gravity theories. It implements
Externí odkaz:
http://arxiv.org/abs/2112.14175