scholarly journals Supernova type Ia data and the cosmic microwave background of modified curvature at short and large distances

2001 ◽  
Vol 65 (2) ◽  
Author(s):  
Mar Bastero-Gil ◽  
Laura Mersini
Keyword(s):  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Type Ia ◽  
Supernova Type Ia

COSMIC CONSTRAINTS ON DECELERATION PARAMETER WITH Sne Ia AND CMB

2009 ◽  
Vol 24 (05) ◽  
pp. 369-376 ◽  
Author(s):  
LIXIN XU ◽  
JIANBO LU
Keyword(s):  
Cosmic Microwave Background ◽  
Observational Data ◽  
Deceleration Parameter ◽  
Background Radiation ◽  
Cosmic Microwave Background Radiation ◽  
Accelerated Expansion ◽  
Microwave Background ◽  
Strong Constraint ◽  
Microwave Background Radiation ◽  
Type Ia

In this paper, a parametrized deceleration parameter q(a) = q0+q1(1-a) is constrained by using the current cosmic observational data from type Ia Supernova (Sne Ia) and Cosmic Microwave Background Radiation (CMB). When the CMB dataset is added as a strong constraint, it is found that the 1σ error is largely reduced. The values of transition redshift zT from decelerated expansion to accelerated expansion and current deceleration parameter q0 are larger than that obtained from the case where Sne Ia dataset is used alone. With comparison to the case of Sne Ia 182 dataset used,15 it is found that the value of transition redshift is smaller than that in Sne 192 dataset case. This is the so-called dataset dependence.

scholarly journals Can f(R) gravity relieve $$H_0$$ and $$\sigma _8$$ tensions?

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Deng Wang
Keyword(s):  
Cosmic Microwave Background ◽  
Confidence Level ◽  
Cosmological Parameters ◽  
Type Ia Supernovae ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Type Ia ◽  
Baryon Acoustic Oscillations ◽  
Ia Supernovae

AbstractTo investigate whether f(R) gravity can relieve current $$H_0$$ H 0 and $$\sigma _8$$ σ 8 tensions, we constrain the Hu-Sawicki f(R) gravity with Planck-2018 cosmic microwave background and redshift space distortions observations. We find that this model fails to relieve both $$H_0$$ H 0 and $$\sigma _8$$ σ 8 tensions, and that its two typical parameters $$\log _{10}f_{R0}$$ log 10 f R 0 and n are insensitive to other cosmological parameters. Combining the cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers with redshift space distortions observations, we give our best constraint $$\log _{10}f_{R0}<-6.75$$ log 10 f R 0 < - 6.75 at the $$2\sigma $$ 2 σ confidence level.

scholarly journals IMPROVED LIMITS ON PHOTON VELOCITY OSCILLATIONS

2002 ◽  
Vol 17 (38) ◽  
pp. 2491-2496 ◽  
Author(s):  
ALESSANDRO DE ANGELIS ◽  
REYNALD PAIN
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Constant ◽  
Active Galactic Nuclei ◽  
Gamma Rays ◽  
Optical Spectrum ◽  
Galactic Nuclei ◽  
Type Ia Supernovae ◽  
Microwave Background ◽  
Type Ia ◽  
Ia Supernovae

The mixing of the photon with a hypothetical sterile paraphotonic state would have consequences on the cosmological propagation of photons. The absence of distortions in the optical spectrum of distant Type Ia supernovae allows to extend by two orders of magnitude the previous limit on the Lorentz-violating parameter δ associated to the photon–paraphoton transition, extracted from the absence of distortions in the spectrum of the cosmic microwave background. The new limit is consistent with the interpretation of the dimming of distant Type Ia supernovae as a consequence of a nonzero cosmological constant. Observations of gamma-rays from active galactic nuclei allow to further extend the limit on δ.

Small‐Scale Cosmic Microwave Background Observations at 8.4 GHz

1997 ◽  
Vol 483 (1) ◽  
pp. 38-50 ◽  
Author(s):  
R. Bruce Partridge ◽  
Eric A. Richards ◽  
Edward B. Fomalont ◽  
K. I. Kellerman ◽  
Rogier A. Windhorst
Keyword(s):  
Cosmic Microwave Background ◽  
Small Scale ◽  
Microwave Background
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