scholarly journals SPATIAL RICCI SCALAR DARK ENERGY MODEL

2011 ◽  
Vol 26 (02) ◽  
pp. 317-329 ◽  
Author(s):  
RONG-JIA YANG ◽  
ZONG-HONG ZHU ◽  
FENGQUAN WU
Keyword(s):  
Dark Energy ◽  
Power Spectra ◽  
Ricci Scalar ◽  
Temperature Anisotropy ◽  
Microwave Background ◽  
Cosmic Microwave Background Temperature ◽  
Acceleration Of The Universe ◽  
Background Temperature ◽  
Best Fit ◽  
The Universe

Inspired by the holographic principle, we suggest that the density of dark energy is proportional to the spatial Ricci scalar curvature (SRDE). Such a model is phenomenologically viable. The best fit values of its parameters at 68% confidence level are found to be Ωm 0= 0.259±0.016 and α = 0.261±0.0122, constrained from the Union+CFA3 sample of 397 SNIa and the BAO measurement. We find that the equation of state of SRDE crosses -1 at z ≃ -0.14. The present value of the deceleration parameter q(z) for SRDE is found to be qz = 0~-0.85. The phase transition from deceleration to acceleration of the Universe for SRDE occurs at the redshift zq = 0~0.4. After studying the perturbation of each component of the Universe, we show that the matter power spectra and cosmic microwave background temperature anisotropy are slightly affected by SRDE, compared with ΛCDM.

scholarly journals Decaying Dark Energy in Light of the Latest Cosmological Dataset

Symmetry ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 372 ◽  
Author(s):  
Ivan de Martino
Keyword(s):  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Parameter Space ◽  
Hubble Constant ◽  
Two Dimensions ◽  
Matter Density ◽  
Microwave Background ◽  
Energy Models ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature

Decaying Dark Energy models modify the background evolution of the most common observables, such as the Hubble function, the luminosity distance and the Cosmic Microwave Background temperature–redshift scaling relation. We use the most recent observationally-determined datasets, including Supernovae Type Ia and Gamma Ray Bursts data, along with H ( z ) and Cosmic Microwave Background temperature versus z data and the reduced Cosmic Microwave Background parameters, to improve the previous constraints on these models. We perform a Monte Carlo Markov Chain analysis to constrain the parameter space, on the basis of two distinct methods. In view of the first method, the Hubble constant and the matter density are left to vary freely. In this case, our results are compatible with previous analyses associated with decaying Dark Energy models, as well as with the most recent description of the cosmological background. In view of the second method, we set the Hubble constant and the matter density to their best fit values obtained by the Planck satellite, reducing the parameter space to two dimensions, and improving the existent constraints on the model’s parameters. Our results suggest that the accelerated expansion of the Universe is well described by the cosmological constant, and we argue that forthcoming observations will play a determinant role to constrain/rule out decaying Dark Energy.

scholarly journals Relieving tensions related to the lensing of the cosmic microwave background temperature power spectra

2017 ◽  
Vol 597 ◽  
pp. A126 ◽  
Author(s):  
F. Couchot ◽  
S. Henrot-Versillé ◽  
O. Perdereau ◽  
S. Plaszczynski ◽  
B. Rouillé d’Orfeuil ◽  
...  
Keyword(s):  
Cosmic Microwave Background ◽  
Power Spectra ◽  
Microwave Background ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature

scholarly journals Cosmology with the cosmic microwave background temperature-polarization correlation

2017 ◽  
Vol 602 ◽  
pp. A41 ◽  
Author(s):  
F. Couchot ◽  
S. Henrot-Versillé ◽  
O. Perdereau ◽  
S. Plaszczynski ◽  
B. Rouillé d’Orfeuil ◽  
...  
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
Microwave Background ◽  
Instrumental Noise ◽  
Cosmic Microwave Background Temperature ◽  
Temperature Polarization ◽  
Background Temperature ◽  
The Impact ◽  
Polarization Correlation

We demonstrate that the cosmic microwave background (CMB) temperature-polarization cross-correlation provides accurate and robust constraints on cosmological parameters. We compare them with the results from temperature or polarization and investigate the impact of foregrounds, cosmic variance, and instrumental noise. This analysis makes use of the Planck high-ℓ HiLLiPOP likelihood based on angular power spectra, which takes into account systematics from the instrument and foreground residuals directly modelled using Planck measurements. The temperature-polarization correlation (TE) spectrum is less contaminated by astrophysical emissions than the temperature power spectrum (TT), allowing constraints that are less sensitive to foreground uncertainties to be derived. For ΛCDM parameters, TE gives very competitive results compared to TT. For basic ΛCDM model extensions (such as AL, ∑mν, or Neff), it is still limited by the instrumental noise level in the polarization maps.

scholarly journals Cosmic microwave background: probing the universe from z = 6 to 1100

2006 ◽  
Vol 2 (14) ◽  
pp. 254-254
Author(s):  
David N. Spergel
Keyword(s):  
Cosmic Microwave Background ◽  
Initial Conditions ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Line Of Sight ◽  
Microwave Background ◽  
Physical Conditions ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature ◽  
The Universe

Observations of cosmic microwave background temperature and polarization fluctuations are sensitive to both physical conditions at recombination (z = 1100) and physical process along the line of sight. I will discuss recent results from the Wilkinson Microwave Anisotropy Probe and planned ground and space-based observations. The talk will emphasize the role of CMB observations in determining the initial conditions for the growth of structure and as a probe of the physics of re-ionization.

BAND-POWER RECONSTRUCTION OF PRIMORDIAL PERTURBATION SPECTRUM FROM CMB ANISOTROPY

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1478-1488 ◽  
Author(s):  
RYO NAGATA ◽  
JUN'ICHI YOKOYAMA
Keyword(s):  
Matrix Analysis ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Inversion Method ◽  
First Year ◽  
Temperature Anisotropy ◽  
Microwave Background ◽  
Band Power ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature ◽  
Rule Out

The primordial curvature fluctuation spectrum is reconstructed in terms of the cosmic inversion method using the Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background temperature anisotropy. Applying the covariance matrix analysis, the reconstructed spectrum is decomposed into statistically independent band powers. It is found that while statistically significant deviation from a simple power-law spectrum is found for first-year data, no such deviation is found for the three-year data except possibly at one point near the border of the wavenumber domain where accurate reconstruction is possible. This result, however, does not necessarily rule out theories predicting modulations in the power spectrum.

scholarly journals On the Cosmological Origin of the Rest Mass of Elementary Particles: The Ideas of Maximons and Minimons Revisited

2019 ◽  
Author(s):  
Girish T.E ◽  
Vipindas V ◽  
Radhakrishnan Nair C
Keyword(s):  
Rest Mass ◽  
Big Bang ◽  
Elementary Particles ◽  
Primordial Black Holes ◽  
Microwave Background ◽  
Compton Wavelength ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature ◽  
Planck Time ◽  
The Universe

It is suggested that physical properties of common elementary particles can be associated with microscopic Primordial Black Holes (PBH) which is inferred to have formed between 10−24 to 10−20 seconds from Big bang in the early universe. This is also found to be related to the phenomenon of Hawking radiation from these PBH. We have revisited the properties of minimons and maximons introduced by Markov [1] in this context. Planck particles which is inferred to form near Planck time (3.857 ×10−43 seconds) are identified as maximons with a mass √πmp where mp is the Planck mass. The minimons are associated with a PBH with Hawking temperature identical with the cosmic microwave background temperature of the universe. The mass of the minimons are found to be comparable to that of the lightest neutrinos (0.0185 eV). They also possess highest Compton wavelength (10−4 m) known for an elementary particle.

The cosmic microwave background: from discovery to precision cosmology

2019 ◽  
pp. 291-345
Author(s):  
R. Bruce Partridge
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Power Spectra ◽  
Expansion Rate ◽  
Microwave Background ◽  
The Universe ◽  
Cosmic Origin ◽  
Precision Cosmology

Observations of the cosmic microwave background (CMB) form the basis for modern ‘precision cosmology’. This chapter treats the discovery of a ≈3 K microwave background and the demonstration of its cosmic origin. Key observational results, up to and including the results from the COBE mission, follow. The major impact of the CMB comes from measurements of the power spectra of fluctuations in the temperature and polarization. The chapter ends with results derived from the power spectra obtained by the Planck mission, including values for the baryon, dark matter, and dark energy densities; the curvature of space; and the expansion rate of the Universe.

scholarly journals The evolution of the cosmic microwave background temperature

2011 ◽  
Vol 526 ◽  
pp. L7 ◽  
Author(s):  
P. Noterdaeme ◽  
P. Petitjean ◽  
R. Srianand ◽  
C. Ledoux ◽  
S. López
Keyword(s):  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature
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