scholarly journals Analysis on the Evolution of the Effective Geff from Linear Nash-Green Fluctuations

2020 ◽  
Author(s):  
Abraao J.S. Capistrano ◽  
Luís A. Cabral ◽  
José A. P. F. Marão ◽  
Carlos H. Coimbra-Araújo
Keyword(s):  
Large Scale ◽  
Time Derivative ◽  
Extrinsic Curvature ◽  
Big Bang ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Density Growth ◽  
Conformal Gauge ◽  
Newtonian Constant ◽  
Best Fit

From the linear Nash-Green fluctuations of background metric, we present the perturbation equations in an embedded four space-time. In the context of a five-dimensional bulk, we show that the perturbations are only propagated by the gravitational tensorial field equation. In a Newtonian conformal gauge, we study the matter density evolution in sub-horizon regime and on how such scale may be affected by the extrinsic curvature. We use the "extended Gold 2018'' growth dataset with 25 datapoints and the best fit Planck2018/LambdaCDM parameters. Hence, we determine the evolution equation for the density growth delta(a) as a result from the embedded equations of the background geometry. By using solar constraints, we analyse the evolution of the effective Newtonian constant Geff and showing that applying Taylor expansion to Geff (a) under the constraint of time-derivative of Geff(0)=G at a= 1 in matter domination era, we get an agreement with Big Bang Nucleosynthesis (BBN) and also an alleviation of the 3-sigma tension to 1-sigma contour between (sigma8-Omegam) of the observations from Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) probes.

scholarly journals Evolution of Growth Density Equation by Constraints on Effective Newtonian Constant Geff

2020 ◽  
Author(s):  
Abraao Capistrano
Keyword(s):  
Extrinsic Curvature ◽  
Big Bang ◽  
Field Equations ◽  
Big Bang Nucleosynthesis ◽  
Acceleration Of The Universe ◽  
Growth Profiles ◽  
Newtonian Constant ◽  
Density Equation ◽  
The Universe ◽  
Bulk Space

The acceleration of the universe is described as a consequence of the extrinsic curvature of the space-time embedded in a bulk space, defined by the Einstein-Hilbert. Using the linear approximation of Nash-Green theorem, we obtain the related perturbed equations in which just the gravitational-tensor field equations contribute to propagation of cosmological perturbations. In accordance with Big Bang Nucleosynthesis and solar constraints, we calculate numerically the effective Newtonian function Geff to constrain the related parameters of the model. We numerically solve the growth density equation for two possible family of solutions leading to an interesting overdensity and, in some cases, a mild damping of the growth profiles, with a top amplification of the growth perturbations around 14% in comparison with LCDM model and quintessence. The effective gravitational Phi and Newtonian curvature Psi are also analysed showing mild perturbations in early times induced only by the extrinsic curvature differently from the LambdaCDM standards.

scholarly journals Cosmological moduli and the post-inflationary universe: A critical review

2015 ◽  
Vol 24 (08) ◽  
pp. 1530022 ◽  
Author(s):  
Gordon Kane ◽  
Kuver Sinha ◽  
Scott Watson
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Big Bang ◽  
Inflationary Universe ◽  
Beyond The Standard Model ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
History Of ◽  
M Theory

We critically review the role of cosmological moduli in determining the post-inflationary history of the universe. Moduli are ubiquitous in string and M-theory constructions of beyond the Standard Model physics, where they parametrize the geometry of the compactification manifold. For those with masses determined by supersymmetry (SUSY) breaking this leads to their eventual decay slightly before Big Bang nucleosynthesis (BBN) (without spoiling its predictions). This results in a matter dominated phase shortly after inflation ends, which can influence baryon and dark matter genesis, as well as observations of the cosmic microwave background (CMB) and the growth of large-scale structure. Given progress within fundamental theory, and guidance from dark matter and collider experiments, nonthermal histories have emerged as a robust and theoretically well-motivated alternative to a strictly thermal one. We review this approach to the early universe and discuss both the theoretical challenges and the observational implications.

scholarly journals Large Scale Anisotropy of the Cosmic Microwave Background

1974 ◽  
Vol 63 ◽  
pp. 157-162 ◽  
Author(s):  
R. B. Partridge
Keyword(s):  
Angular Distribution ◽  
Large Scale ◽  
Background Radiation ◽  
Big Bang ◽  
Microwave Background ◽  
Initial State ◽  
Microwave Background Radiation ◽  
Cosmological Data ◽  
The Big Bang ◽  
The Universe

It is now generally accepted that the microwave background radiation, discovered in 1965 (Penzias and Wilson, 1965; Dicke et al., 1965), is cosmological in origin. Measurements of the spectrum of the radiation, discussed earlier in this volume by Blair, are consistent with the idea that the radiation is in fact a relic of a hot, dense, initial state of the Universe – the Big Bang. If the radiation is cosmological, measurements of both its spectrum and its angular distribution are capable of providing important – and remarkably precise – cosmological data.

scholarly journals Unlocking the synergy between CMB spectral distortions and anisotropies

2021 ◽  
Vol 2021 (12) ◽  
pp. 050
Author(s):  
Hao Fu ◽  
Matteo Lucca ◽  
Silvia Galli ◽  
Elia S. Battistelli ◽  
Deanna C. Hooper ◽  
...  
Keyword(s):  
Spectral Index ◽  
Big Bang ◽  
Noise Levels ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Scalar Spectral Index ◽  
New Information ◽  
Wide Range ◽  
Inflationary Parameters ◽  
Better Than

Abstract Measurements of the cosmic microwave background (CMB) spectral distortions (SDs) will open a new window on the very early universe, providing new information complementary to that gathered from CMB temperature and polarization anisotropies. In this paper, we study their synergy as a function of the characteristics of the considered experiments. In particular, we examine a wide range of sensitivities for possible SD measurements, spanning from FIRAS up to noise levels 1000 times better than PIXIE, and study their constraining power when combined with current or future CMB anisotropy experiments such as Planck or LiteBIRD plus CMB-S4. We consider a number of different cosmological models such as the ΛCDM, as well as its extensions with the running of the scalar spectral index, the decay or the annihilation of dark matter (DM) particles. While upcoming CMB anisotropy experiments will be able to decrease the uncertainties on inflationary parameters such as As and ns by about a factor 2 in the ΛCDM case, we find that an SD experiment 100 times more sensitive than PIXIE (comparable to the proposed Super-PIXIE satellite) could potentially further contribute to constrain these parameters. This is even more significant in the case of the running of the scalar spectral index. Furthermore, as expected, constraints on DM particles decaying at redshifts probed by SDs will improve by orders of magnitude even with an experiment 10 times worse than PIXIE as compared to CMB anisotropies or Big Bang Nucleosynthesis bounds. On the contrary, DM annihilation constraints will not significantly improve over CMB anisotropy measurements. Finally, we forecast the constraints obtainable with sensitivities achievable either from the ground or from a balloon.

scholarly journals Reconstructing the EFT of inflation from cosmological data

2019 ◽  
Vol 7 (4) ◽  
Author(s):  
Amel Durakovic ◽  
Paul Hunt ◽  
Subodh Patil ◽  
Subir Sarkar
Keyword(s):  
Large Scale ◽  
Effective Theory ◽  
De Sitter ◽  
Microwave Background ◽  
Functional Parameters ◽  
Primordial Power Spectrum ◽  
Cosmological Data ◽  
Cent Level ◽  
Best Fit ◽  
Adiabatic Mode

Reconstructions of the primordial power spectrum (PPS) of curvature perturbations from cosmic microwave background anisotropies and large-scale structure data suggest that the usually assumed power-law PPS has localised features (up to \sim 10\%∼10% in amplitude), although of only marginal significance in the framework of \LambdaΛCDM cosmology. On the other hand if the cosmology is taken to be Einstein-de Sitter, larger features in the PPS (up to \sim 20\%∼20% in amplitude) are required to accurately fit the observed acoustic peaks. Within the context of single clock inflation, we show that any given reconstruction of the PPS can be mapped on to functional parameters of the underlying effective theory of the adiabatic mode within a 2nd-order formalism, provided the best fit fractional change of the PPS, \Delta{P}_{R}/{P}_{R}ΔPR/PR is such that (\Delta{P}_{R}/{P}_{R})^3(ΔPR/PR)3 falls within the 1\,\sigma1σ confidence interval of the reconstruction for features induced by variations of either the sound speed c_\mathrm{s}cs or the slow-roll parameter \epsilonϵ. Although there is a degeneracy amongst these functional parameters (and the models that project onto them), we can identify simple representative inflationary models that yield such features in the PPS. Thus we provide a dictionary (more accurately, a thesaurus) to go from observational data, via the reconstructed PPS, to models that reproduce them to per cent level precision.

scholarly journals A new tension in the cosmological model from primordial deuterium?

2021 ◽  
Vol 502 (2) ◽  
pp. 2474-2481
Author(s):  
Cyril Pitrou ◽  
Alain Coc ◽  
Jean-Philippe Uzan ◽  
Elisabeth Vangioni
Keyword(s):  
Big Bang ◽  
Reaction Cross ◽  
Light Elements ◽  
Neutron Lifetime ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Baryonic Density ◽  
The Status ◽  
Big Bang Model ◽  
The Big Bang

ABSTRACT Recent measurements of the D(p,γ)3He nuclear reaction cross-section and of the neutron lifetime, along with the reevaluation of the cosmological baryon abundance from cosmic microwave background (CMB) analysis, call for an update of abundance predictions for light elements produced during the big-bang nucleosynthesis (BBN). While considered as a pillar of the hot big-bang model in its early days, BBN constraining power mostly rests on deuterium abundance. We point out a new ≃1.8σ tension on the baryonic density, or equivalently on the D/H abundance, between the value inferred on one hand from the analysis of the primordial abundances of light elements and, on the other hand, from the combination of CMB and baryonic oscillation data. This draws the attention on this sector of the theory and gives us the opportunity to reevaluate the status of BBN in the context of precision cosmology. Finally, this paper presents an upgrade of the BBN code primat.

scholarly journals STRUCTURE FORMATION WITH MIRROR DARK MATTER: CMB AND LSS

2005 ◽  
Vol 14 (01) ◽  
pp. 107-119 ◽  
Author(s):  
ZURAB BEREZHIANI ◽  
PAOLO CIARCELLUTI ◽  
DENIS COMELLI ◽  
FRANCESCO L. VILLANTE
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Big Bang ◽  
Dark Matter Candidate ◽  
Microwave Background ◽  
Quantitative Calculation ◽  
World Hypothesis ◽  
The Big Bang

In the mirror world hypothesis, the mirror baryonic component emerges as a possible dark matter candidate. An immediate question arises: how do the mirror baryons behave and what are their differences from the more familiar dark matter candidates such as cold dark matter? In this paper, we answer this question quantitatively. First, we discuss the dependence of the relevant scales for the structure formation (Jeans and Silk scales) on the two macroscopic parameters necessary to define the model: the temperature of the mirror plasma (limited by the Big Bang Nucleosynthesis) and the amount of mirror baryonic matter. Then we perform a complete quantitative calculation of the implications of mirror dark matter on the cosmic microwave background and large scale structure power spectrum. Finally, confronting with the present observational data, we obtain some bounds on the mirror parameter space.

scholarly journals Testing a Dilaton Gravity Model Using Nucleosynthesis

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Boran ◽  
E. O. Kahya
Keyword(s):  
Steady State ◽  
Gravity Model ◽  
Big Bang ◽  
Universe Model ◽  
Light Elements ◽  
Dilaton Gravity ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Higher Dimensional ◽  
State Universe

Big bang nucleosynthesis (BBN) offers one of the most strict evidences for theΛ-CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D,3He,4He, T, and7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model andΛ-CDM in the light of the astrophysical observations.

Measurement of the microwave background radiation

1986 ◽  
Vol 320 (1556) ◽  
pp. 595-607 ◽  
Keyword(s):  
Large Scale ◽  
Background Radiation ◽  
Big Bang ◽  
Spectral Distortion ◽  
Microwave Background ◽  
Spatial Fluctuations ◽  
The Galaxy ◽  
Microwave Background Radiation ◽  
History Of ◽  
Flux Measurements

Absolute flux measurements of the 2.7 K background radiation show a blackbody spectrum with good accuracy ( ca . + 5 %) over two orders of magnitude of wavelength (12 cm to 1 mm). This is in agreement with the thermal history of matter and radiation envisaged by the hot Big Bang model. In particular, experimental limits on spectral distortion constrain processes that release energy into the early Universe. The extreme isotropy of the 2.7 K radiation on small angular scales (10" to 1°) sets interesting limits on models for the formation of mass structure. Some types of perturbations can be ruled out because the accompanying spatial fluctuations in radiation temperature are not seen (Δ T / T < 10 -4 ). Large-scale (1-90°) anisotropy of the radiation is plausible because at the time of decoupling (z « 1000), regions separated by more than a few degrees in the sky were not in causal contact. Explanation of the observed isotropy is a major feature of inflationary models. Finally, the observed dipole anisotropy is mostly due to the peculiar velocity of the Galaxy with respect to the radiation frame. An interesting question is: how much of this velocity is primordial and how much can be accounted for by local mass attractors?

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