scholarly journals Constraints on the Equation of State of Dark Energy and the Hubble Constant from Stellar Ages and the Cosmic Microwave Background

2003 ◽  
Vol 593 (2) ◽  
pp. 622-629 ◽  
Author(s):  
Raul Jimenez ◽  
Licia Verde ◽  
Tommaso Treu ◽  
Daniel Stern
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmic Microwave Background ◽  
Hubble Constant ◽  
Microwave Background ◽  
Stellar Ages

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 A fake interacting dark energy detection?

2020 ◽  
Vol 500 (1) ◽  
pp. L22-L26
Author(s):  
Eleonora Di Valentino ◽  
Olga Mena
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Hubble Constant ◽  
Energy Detection ◽  
Microwave Background ◽  
Planck Data ◽  
Cosmological Constraints ◽  
Data Analyses ◽  
Constant Tension

ABSTRACT Models involving an interaction between the dark matter and the dark energy sectors have been proposed to alleviate the long-standing Hubble constant tension. In this paper, we analyse whether the constraints and potential hints obtained for these interacting models remain unchanged when using simulated Planck data. Interestingly, our simulations indicate that a dangerous fake detection for a non-zero interaction among the dark matter and the dark energy fluids could arise when dealing with current cosmic microwave background (CMB) Planck measurements alone. The very same hypothesis is tested against future CMB observations, finding that only cosmic variance limited polarization experiments, such as PICO or PRISM, could be able to break the existing parameter degeneracies and provide reliable cosmological constraints. This paper underlines the extreme importance of confronting the results arising from data analyses with those obtained with simulations when extracting cosmological limits within exotic cosmological scenarios.

scholarly journals Mapping the Dark Energy Equation of State

2005 ◽  
Vol 216 ◽  
pp. 59-66
Author(s):  
Eric V. Linder
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Cosmic Microwave Background ◽  
Structure Formation ◽  
Energy Equation ◽  
Microwave Background ◽  
Redshift Surveys ◽  
Expansion Of The Universe ◽  
The Universe

The acceleration of the expansion of the universe has deep implications for structure formation, the composition of the universe, and its fate. Roughly 70% of the energy density is in a dark energy, whose nature remains unknown. Mapping the expansion history through supernovae, mapping the geometry of the universe and formation of structure through redshift surveys, and mapping the distance to recombination through the cosmic microwave background provide complementary, precise probes of the equation of state of the dark energy. Together these next generation maps of the cosmos can reveal not only the value today, but the redshift variation, of the equation of state, providing a critical clue to the underlying physics.

scholarly journals Phantom Braneworld and the Hubble Tension

2021 ◽  
Vol 923 (2) ◽  
pp. 212
Author(s):  
Satadru Bag ◽  
Varun Sahni ◽  
Arman Shafieloo ◽  
Yuri Shtanov
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmic Microwave Background ◽  
Data Sets ◽  
Microwave Background ◽  
Effective Equation ◽  
Induced Gravity ◽  
Cosmic Evolution ◽  
Local Measurements ◽  
Braneworld Model

Abstract Braneworld models with induced gravity exhibit phantom-like behavior of the effective equation of state of dark energy. They can, therefore, naturally accommodate higher values of H 0, preferred by recent local measurements while satisfying the cosmic microwave background constraints. We test the background evolution in such phantom braneworld scenarios with the current observational data sets. We find that the phantom braneworld prefers a higher value of H 0 even without the R19 prior, thereby providing a much better fit to the local measurements. Although this braneworld model cannot fully satisfy all combinations of cosmological observables, among existing dark energy candidates the phantom brane provides one of the most compelling explanations of cosmic evolution.

scholarly journals KiDS+VIKING-450 and DES-Y1 combined: Cosmology with cosmic shear

2020 ◽  
Vol 638 ◽  
pp. L1 ◽  
Author(s):  
S. Joudaki ◽  
H. Hildebrandt ◽  
D. Traykova ◽  
N. E. Chisari ◽  
C. Heymans ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Gravitational Lensing ◽  
Error Model ◽  
Calibration Error ◽  
Microwave Background ◽  
Weak Gravitational Lensing ◽  
Dark Energy Survey ◽  
Cosmic Shear ◽  
Energy Survey

We present a combined tomographic weak gravitational lensing analysis of the Kilo Degree Survey (KV450) and the Dark Energy Survey (DES-Y1). We homogenize the analysis of these two public cosmic shear datasets by adopting consistent priors and modeling of nonlinear scales, and determine new redshift distributions for DES-Y1 based on deep public spectroscopic surveys. Adopting these revised redshifts results in a 0.8σ reduction in the DES-inferred value for S​8, which decreases to a 0.5σ reduction when including a systematic redshift calibration error model from mock DES data based on the MICE2 simulation. The combined KV450+DES-Y1 constraint on S8 = 0.762−0.024+0.025 is in tension with the Planck 2018 constraint from the cosmic microwave background at the level of 2.5σ. This result highlights the importance of developing methods to provide accurate redshift calibration for current and future weak-lensing surveys.

scholarly journals Scalar field dark energy and cosmic microwave background

2003 ◽  
Vol 124 ◽  
pp. 68-71 ◽  
Author(s):  
C. Baccigalupi ◽  
A. Balbi ◽  
S. Matarrese ◽  
F. Perrotta ◽  
N. Vittorio
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Cosmic Microwave Background ◽  
Microwave Background
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