Cosmological Constant Decaying with CMB Temperature

2018 ◽  
Author(s):  
Tomohide Sonoda
Keyword(s):  
Cosmological Constant ◽  
Fine Tuning ◽  
Theoretical Modelling ◽  
Microwave Background ◽  
Dark Energy Density ◽  
Large Numbers ◽  
Cosmological Scenario ◽  
The Hierarchical Structure ◽  
The Universe ◽  
Cmb Temperature

Recent observations of the dark energy density demonstrates the fine-tuning problem and challenges in theoretical modelling. In this study, we apply the self-similar symmetry (SSS) model, describing the hierarchical structure of the universe based on the Dirac large numbers hypothesis, to Einstein's cosmological term. We introduce a new similarity dimension, DB, in the SSS model. Using the DB SSS model, the cosmological constant Λ is simply expressed as a function of the cosmic microwave background (CMB) temperature. The result gives a natural interpretation of the cosmological scenario and helps understanding the extreme smallness of the present value of Λ without fine-tuning.

scholarly journals Cosmological constant decaying with CMB temperature

2019 ◽  
Vol 16 (06) ◽  
pp. 1950088 ◽  
Author(s):  
Tomohide Sonoda
Keyword(s):  
Cosmological Constant ◽  
Fine Tuning ◽  
Field Equations ◽  
Microwave Background ◽  
Dark Energy Density ◽  
Dimension Formula ◽  
Large Numbers ◽  
The Hierarchical Structure ◽  
The Universe ◽  
Cmb Temperature

Recent observations of the dark energy density have demonstrated the fine-tuning problem and the challenges faced by theoretical modeling. In this study, we apply the self-similar symmetry (SSS) model, describing the hierarchical structure of the universe based on the Dirac large numbers hypothesis, to Einstein’s cosmological term. We introduce a new similarity dimension, [Formula: see text], in the SSS model. Using the [Formula: see text] SSS model, the cosmological constant [Formula: see text] is simply expressed as a function of the cosmic microwave background (CMB) temperature. The result shows that both the gravitational constant [Formula: see text] and [Formula: see text] are coupled with the CMB temperature, which simplifies the solution of Einstein’s field equations for the variable [Formula: see text]–[Formula: see text] model.

Ω0 Concordance

2005 ◽  
Vol 201 ◽  
pp. 271-281
Author(s):  
Masataka. Fukugita
Keyword(s):  
Dark Matter ◽  
Cosmological Constant ◽  
Structure Formation ◽  
Cold Dark Matter ◽  
Mass Density ◽  
Hubble Constant ◽  
Density Parameter ◽  
Microwave Background ◽  
The Hierarchical Structure ◽  
The Universe

The determinations of the mass density parameter Ω0 are examined with a particular emphasis given to the new cosmic microwave background (CMB) experiments. It is shown that the Ω0 and the Hubble constant H0 from CMB are quite consistent with those from other observations with the aid of the hierarchical structure formation models based on cold dark matter dominance with the cosmological constant that makes the universe flat. The concordance value of Ω0 is 0.25-0.45.

scholarly journals How the Limit Values Work

2021 ◽  
Keyword(s):  
Cosmological Constant ◽  
Gravitational Radius ◽  
Limit Values ◽  
Event Horizons ◽  
Dirac Type ◽  
Large Numbers ◽  
Spatio Temporal ◽  
The Universe ◽  
Limiting Values ◽  
Physical Principles

The efficiency of limiting quantities as a tool for describing physics at various spatio-temporal scales is shown. Due to its universality, limit values allow us to establish relationships between, at first glance, distant from each other's characteristics. The article discusses specific examples of the use of limit values to establish such relationships between quantities at different scales. Based on the principle of reaching the limiting values on the event horizons, a connection was obtained between the Planck values and the values of the Universe. The resulting relation can be attributed to relations of the Dirac type - the coincidence of large numbers that emerged from empirical observations. In the article, the relationships between large numbers of the Dirac type are established proceeding, in a certain sense, from physical principles - the existence of limiting values. It is shown that this ratio is observed throughout the evolution of the Universe. An alternative way of solving the problem of the cosmological constant using limiting values and its relation to the minimum spatial scale is discussed. In addition, a one-parameter family of masses was introduced, including the mass of the Universe, the Planck mass and the mass of the graviton, which also establish relationships between quantities differing by 120 orders of magnitude. It is shown that entropic forces also obey the same universal limiting constraints as ordinary forces. Thus, the existence of limiting values extends to informational limitations in the Universe. It is fundamentally important that on any event horizon, regardless of its scale (i.e., its gravitational radius), the universal value of limit force c4/4G is realized. This allows you to relate the characteristics of the Universe related to various stages of its evolution.

scholarly journals Secondary CMB temperature anisotropies from magnetic reheating

2019 ◽  
Vol 490 (3) ◽  
pp. 4419-4427 ◽  
Author(s):  
Shohei Saga ◽  
Atsuhisa Ota ◽  
Hiroyuki Tashiro ◽  
Shuichiro Yokoyama
Keyword(s):  
Field Amplitude ◽  
Temperature Perturbation ◽  
Linear Parameter ◽  
Spectral Distortion ◽  
Microwave Background ◽  
Linear Coupling ◽  
Non Linear ◽  
Primordial Magnetic Fields ◽  
The Universe ◽  
Cmb Temperature

ABSTRACT Spatially fluctuating primordial magnetic fields (PMFs) inhomogeneously reheat the Universe when they dissipate deep inside the horizon before recombination. Such an energy injection turns into an additional photon temperature perturbation. We investigate secondary cosmic microwave background (CMB) temperature anisotropies originated from this mechanism, which we call inhomogeneous magnetic reheating. We find that it can bring us information about non-linear coupling between PMFs and primordial curvature perturbations parametrized by bNL, which should be important for probing the generation mechanism of PMFs. In fact, by using current CMB observations, we obtain an upper bound on the non-linear parameter as log (bNL(Bλ/nG)2) ≲ − 36.5nB − 94.0 with Bλ and nB being a magnetic field amplitude smoothed over λ = 1 Mpc scale and a spectral index of the PMF power spectrum, respectively. Our constraints are far stronger than a previous forecast based on the future CMB spectral distortion anisotropy measurements because inhomogeneous magnetic reheating covers a much wider range of scales, i.e. 1 Mpc−1 ≲ k ≲ 1015 Mpc−1.

scholarly journals The habitable epoch of the early Universe

2014 ◽  
Vol 13 (4) ◽  
pp. 337-339 ◽  
Author(s):  
Abraham Loeb
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Constant ◽  
Water Chemistry ◽  
Early Universe ◽  
Liquid Water ◽  
Matter Density ◽  
Microwave Background ◽  
Star Forming ◽  
Rocky Planets ◽  
The Universe

AbstractIn the redshift range 100≲(1+z)≲137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100°C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standard ΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts, allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old. The possibility of life starting when the average matter density was a million times bigger than it is today is not in agreement with the anthropic explanation for the low value of the cosmological constant.

scholarly journals Explaining cosmological anisotropy: evidence for causal horizons from CMB data

2021 ◽  
Author(s):  
Pablo Fosalba ◽  
Enrique Gaztañaga
Keyword(s):  
Large Scale ◽  
Cosmological Parameter ◽  
Cosmic Acceleration ◽  
Statistical Fluctuation ◽  
Temperature Anisotropy ◽  
Microwave Background ◽  
Dark Energy Density ◽  
Observable Universe ◽  
Open Question ◽  
The Universe

Abstract The origin of power asymmetry and other measures of statistical anisotropy on the largest scales of the universe, as manifested in Cosmic Microwave Background (CMB) and large-scale structure data, is a long-standing open question in cosmology. In this paper we analyse the Planck Legacy temperature anisotropy data and find strong evidence for a violation of the Cosmological principle of isotropy, with a probability of being a statistical fluctuation of order ∼10−9. The detected anisotropy is related to large-scale directional ΛCDM cosmological parameter variations across the CMB sky, that are sourced by three distinct patches in the maps with circularly-averaged sizes between 40 to 70 degrees in radius. We discuss the robustness of our findings to different foreground separation methods and analysis choices, and find consistent results from WMAP data when limiting the analysis to the same scales. We argue that these well-defined regions within the cosmological parameter maps may reflect finite and casually disjoint horizons across the observable universe. In particular we show that the observed relation between horizon size and mean dark energy density within a given horizon is in good agreement with expectations from a recently proposed model of the universe that explains cosmic acceleration and cosmological parameter tensions between the high and low redshift universe from the existence of casual horizons within our universe.

scholarly journals Thermodynamic Prescription of Cosmological Constant in the Randall-Sundrum II Brane

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Tanwi Bandyopadhyay
Keyword(s):  
Cosmological Constant ◽  
Uncertainty Principle ◽  
Generalized Uncertainty Principle ◽  
Friedmann Equation ◽  
Entropy Function ◽  
Flat Universe ◽  
Corrected Entropy ◽  
Cosmological Scenario ◽  
Equipartition Law ◽  
The Universe

In this work, we apply the quantum corrected entropy function derived from the Generalized Uncertainty Principle (GUP) to the holographic equipartition law to study the cosmological scenario in the Randall-Sundrum (RS) II brane. An extra driving term has come up in the effective Friedmann equation for a homogeneous, isotropic, and spatially flat universe. Further, thermodynamic prescription of the universe constraints this term eventually with an order equivalent to that of the cosmological constant.

Cosmology in multiply warped braneworld scenario

2014 ◽  
Vol 29 (13) ◽  
pp. 1450069 ◽  
Author(s):  
Narayan Banerjee ◽  
Sayantani Lahiri ◽  
Soumitra SenGupta
Keyword(s):  
Cosmological Constant ◽  
Extra Dimensions ◽  
Fine Tuning ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Hubble Expansion ◽  
Cosmological Scenario ◽  
Higher Dimensional ◽  
Gauge Hierarchy ◽  
Bulk Cosmological Constant

Hubble expansion in warped braneworld model is addressed in the presence of more than one warped extra dimensions. Some distinct phenomenological signatures of such model has already been discussed in the context of collider-based experiments as well as to explain the fermion mass hierarchy in the Standard Model of elementary particles. In this paper, we explore some cosmological implications of such a model. It is shown that while the expansion depends on all the moduli, an exponential nature of the expansion of the scale factor emerges as a generic feature which is independent of the number of extra dimensions but depends only on the bulk cosmological constant and brane pressure. A generalized expression for the effective 3-brane cosmological constant in such model has been derived. This generalizes the well-known fine tuning/detuning between the bulk cosmological constant and brane tension to obtain the desired cosmological constant on the brane. The warped factor corresponding to the higher-dimensional cosmological scenario is determined and the issue of gauge hierarchy problem is discussed.

scholarly journals Cosmological Constant in SUGRA Models with Degenerate Vacua

Universe ◽  
2019 ◽  
Vol 5 (10) ◽  
pp. 214
Author(s):  
Colin Froggatt ◽  
Holger Nielsen ◽  
Roman Nevzorov ◽  
Anthony Thomas
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Scalar Potential ◽  
Planck Scale ◽  
Susy Breaking ◽  
Fine Tuning ◽  
Tree Level ◽  
Vacuum Energy Density ◽  
Multiple Point ◽  
Dark Energy Density

The extrapolation of couplings up to the Planck scale within the standard model (SM) indicates that the Higgs effective potential can have two almost degenerate vacua, which were predicted by the multiple point principle (MPP). The application of the MPP to ( N = 1 ) supergravity (SUGRA) implies that the SUGRA scalar potential of the hidden sector possesses at least two exactly degenerate minima. The first minimum is associated with the physical phase in which we live. In the second supersymmetric (SUSY) Minkowski vacuum, the local SUSY may be broken dynamically, inducing a tiny vacuum energy density. In this paper, we consider the no-scale-inspired SUGRA model in which the MPP conditions are fulfilled without any extra fine-tuning at the tree-level. Assuming that at high energies, the couplings in both phases are identical, one can estimate the dark energy density in these vacua. Using the two-loop renormalization group (RG) equations, we find that the measured value of the cosmological constant can be reproduced if the SUSY breaking scale M S in the physical phase is of the order of 100 TeV. The scenario with the Planck scale SUSY breaking is also discussed.

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