scholarly journals A new comparison between holographic dark energy and standard $$\varLambda $$-cosmology in the context of cosmography method

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Saeed Pourojaghi ◽  
Mohammad Malekjani
Keyword(s):  
Dark Energy ◽  
Hubble Parameter ◽  
Gamma Ray ◽  
Holographic Dark Energy ◽  
Error Function ◽  
Hubble Diagram ◽  
Type Ia ◽  
Independent Technique ◽  
Model Independent ◽  
Ia Supernovae

AbstractThe cosmography method is a model-independent technique used to reconstruct the Hubble expansion of the Universe at low redshifts. In this method, using the Hubble diagrams from Type Ia Supernovae (SNIa) in Pantheon catalog, quasars and Gamma-Ray Bursts (GRB), we put observational constraints on the cosmographic parameters in holographic dark energy (HDE) and concordance $$\varLambda $$ Λ CDM models by minimizing the error function $$\chi ^2$$ χ 2 based on the statistical Markov Chain Monte Carlo (MCMC) algorithm. Then, we compare the results of the models with the results of the model-independent cosmography method. Except for the Pantheon sample, we observe that there is a big tension between standard cosmology and Hubble diagram observations, while the HDE model remains consistent in all cases. Then we use different combinations of Hubble diagram data to reconstruct the Hubble parameter of the model and compare it with the observed Hubble data. We observe that the Hubble parameter reconstructed from the model-independent cosmography method has the smallest deviation from the Hubble data and the $$\varLambda $$ Λ CDM (HDE) model has the largest (middle) deviation, especially when we keep the observational data point $$226^{+8.0}_{-0.8}$$ 226 - 0.8 + 8.0 at redshift $$z=2.36$$ z = 2.36 in the analysis. On the contrary, in the redshift $$z <1$$ z < 1 , we see that the compatibility of $$\varLambda $$ Λ CDM cosmology and observation is even better than the model independent cosmography method.

scholarly journals Observations of Type Ia Supernovae and Challenges for Cosmology

2005 ◽  
Vol 192 ◽  
pp. 525-533
Author(s):  
Weidong Li ◽  
Alexei V. Filippenko
Keyword(s):  
Dark Energy ◽  
Light Curve ◽  
Rise Time ◽  
Accelerating Universe ◽  
Type Ia Supernovae ◽  
Hubble Diagram ◽  
High Quality ◽  
Type Ia ◽  
Secondary Parameter ◽  
Ia Supernovae

SummaryObservations of Type Ia supernovae (SNe Ia) reveal correlations between their luminosities and light-curve shapes, and between their spectral sequence and photometric sequence. Assuming SNe Ia do not evolve at different redshifts, the Hubble diagram of SNe Ia may indicate an accelerating Universe, the signature of a cosmological constant or other forms of dark energy. Several studies raise concerns about the evolution of SNe Ia (e.g., the peculiarity rate, the rise time, and the color of SNe Ia at different redshifts), but all these studies suffer from the difficulties of obtaining high-quality spectroscopy and photometry for SNe Ia at high redshifts. There are also some troubling cases of SNe Ia that provide counter examples to the observed correlations, suggesting that a secondary parameter is necessary to describe the whole SN Ia family. Understanding SNe Ia both observationally and theoretically will be the key to boosting confidence in the SN Ia cosmological results.

scholarly journals Testing the isotropy of the Universe with Type Ia supernovae in a model-independent way

2017 ◽  
Vol 474 (3) ◽  
pp. 3516-3522 ◽  
Author(s):  
Yu-Yang Wang ◽  
F Y Wang
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Light Curve ◽  
Type Ia Supernovae ◽  
Anisotropic Universe ◽  
Preferred Direction ◽  
Type Ia ◽  
Model Independent ◽  
Ia Supernovae ◽  
The Universe

Abstract In this paper, we study an anisotropic universe model with Bianchi-I metric using Joint light-curve analysis (JLA) sample of Type Ia supernovae (SNe Ia). Because light-curve parameters of SNe Ia vary with different cosmological models and SNe Ia samples, we fit the SNe Ia light-curve parameters and cosmological parameters simultaneously employing Markov chain Monte Carlo method. Therefore, the results on the amount of deviation from isotropy of the dark energy equation of state (δ), and the level of anisotropy of the large-scale geometry (Σ0) at present, are totally model-independent. The constraints on the skewness and cosmic shear are −0.101 &lt; δ &lt; 0.071 and −0.007 &lt; Σ0 &lt; 0.008. This result is consistent with a standard isotropic universe (δ = Σ0 = 0). However, a moderate level of anisotropy in the geometry of the Universe and the equation of state of dark energy, is allowed. Besides, there is no obvious evidence for a preferred direction of anisotropic axis in this model.

scholarly journals Testing the distance–duality relation from strong gravitational lensing, type Ia supernovae and gamma-ray bursts data up to redshift z ∼ 3.6

2017 ◽  
Vol 26 (09) ◽  
pp. 1750097 ◽  
Author(s):  
Xiangyun Fu ◽  
Pengcheng Li
Keyword(s):  
Cosmological Model ◽  
Gravitational Lensing ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Type Ia Supernovae ◽  
Redshift Range ◽  
Strong Gravitational Lensing ◽  
Type Ia ◽  
Model Independent ◽  
Ia Supernovae

In this paper, we perform a cosmological model-independent test of the cosmic distance–duality relation (CDDR) in terms of the ratio of angular diameter distance (ADD) [Formula: see text] from strong gravitational lensing (SGL) and the ratio of luminosity distance (LD) [Formula: see text] obtained from the joint of type Ia supernovae (SNIa) Union2.1 compilation and the latest Gamma-Ray Bursts (GRBs) data, where the superscripts s and l correspond to the redshifts [Formula: see text] and [Formula: see text] at the source and lens from SGL samples. The purpose of combining GRB data with SNIa compilation is to test CDDR in a wider redshift range. The LD associated with the redshifts of the observed ADD is obtained through two cosmological model-independent methods, namely, method A: binning the SNIa+GRBs data, and method B: reconstructing the function of DL by combining the Crossing Statistic with the smoothing method. We find that CDDR is compatible with the observations at [Formula: see text] confidence level for the power law model which is assumed to describe the mass distribution of lensing systems with method B in a wider redshift range.

scholarly journals Constructing a cosmological model-independent Hubble diagram of type Ia supernovae with cosmic chronometers

2016 ◽  
Vol 93 (4) ◽  
Author(s):  
Zhengxiang Li ◽  
J. E. Gonzalez ◽  
Hongwei Yu ◽  
Zong-Hong Zhu ◽  
J. S. Alcaniz
Keyword(s):  
Cosmological Model ◽  
Type Ia Supernovae ◽  
Hubble Diagram ◽  
Type Ia ◽  
Model Independent ◽  
Ia Supernovae

scholarly journals Utilizing the Updated Gamma-Ray Bursts and Type Ia Supernovae to Constrain the Cardassian Expansion Model and Dark Energy

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Jun-Jie Wei ◽  
Qing-Bo Ma ◽  
Xue-Feng Wu
Keyword(s):  
Dark Energy ◽  
Gamma Ray ◽  
Interpolation Method ◽  
Spline Interpolation ◽  
Confidence Region ◽  
Type Ia Supernovae ◽  
Distance Modulus ◽  
Type Ia ◽  
Ia Supernovae ◽  
Expansion Model

We update gamma-ray burst (GRB) luminosity relations among certain spectral and light-curve features with 139 GRBs. The distance modulus of 82 GRBs atz>1.4can be calibrated with the sample atz≤1.4by using the cubic spline interpolation method from the Union2.1 Type Ia supernovae (SNe Ia) set. We investigate the joint constraints on the Cardassian expansion model and dark energy with 580 Union2.1 SNe Ia sample(z<1.4)and 82 calibrated GRBs’ data(1.4<z≤8.2). In ΛCDM, we find that adding 82 high-zGRBs to 580 SNe Ia significantly improves the constraint onΩm-ΩΛplane. In the Cardassian expansion model, the best fit isΩm=0.24-0.15+0.15andn=0.16-0.52+0.30  (1σ), which is consistent with the ΛCDM cosmology(n=0)in the1σconfidence region. We also discuss two dark energy models in which the equation of statew(z)is parameterized asw(z)=w0andw(z)=w0+w1z/(1+z), respectively. Based on our analysis, we see that our universe at higher redshift up toz=8.2is consistent with the concordance model within1σconfidence level.

Toward cosmological-model-independent calibrations for the luminosity relations of Gamma-Ray Bursts

2015 ◽  
Vol 24 (07) ◽  
pp. 1550057 ◽  
Author(s):  
Xuheng Ding ◽  
Zhengxiang Li ◽  
Zong-Hong Zhu
Keyword(s):  
Cosmological Model ◽  
Gamma Ray ◽  
Distance Estimation ◽  
Gamma Ray Bursts ◽  
Type Ia ◽  
Model Independent ◽  
Global Fit ◽  
Ia Supernovae ◽  
Distance Indicators ◽  
The Universe

Gamma-ray bursts (GRBs), have been widely used as distance indicators to measure the cosmic expansion and explore the nature of dark energy. A popular method adopted in previous works is to calibrate the luminosity relations which are responsible for distance estimation of GRBs with more primary (low redshift) cosmic distance ladder objects, type Ia supernovae (SNe Ia). Since distances of SNe Ia in all SN Ia samples used to calibrate GRB luminosity relations were usually derived from the global fit in a specific cosmological model, the distance of GRB at a given redshift calibrated with matching SNe Ia was still cosmological-model-dependent. In this paper, we first directly determine the distances of SNe Ia with the Angular Diameter Distances (ADDs) of galaxy clusters without any assumption for the background of the universe, and then calibrate GRB luminosity relations with our cosmology-independent distances of SNe Ia. The results suggest that, compared to the previous original manner where distances of SNe Ia used as calibrators are determined from the global fit in a particular cosmological model, our treatments proposed here yield almost the same calibrations of GRB luminosity relations and the cosmological implications of them do not suffer any circularity.

scholarly journals Update constraints on neutrino mass and mass hierarchy in light of dark energy models

2020 ◽  
Vol 29 (13) ◽  
pp. 2050088
Author(s):  
Zhenjie Liu ◽  
Haitao Miao
Keyword(s):  
Dark Energy ◽  
Neutrino Masses ◽  
Mass Hierarchy ◽  
Acoustic Oscillations ◽  
Energy Models ◽  
Background Data ◽  
Type Ia ◽  
Model Independent ◽  
Degenerate Neutrino ◽  
Ia Supernovae

Combining cosmic microwave (CMB) background data from Planck satellite data, Baryon Acoustic Oscillations (BAO) measurements and Type Ia supernovae (SNe Ia) data, we obtain the bounds on total neutrino masses [Formula: see text] with the approximation of degenerate neutrino masses and for three dark energy models: the cosmological constant ([Formula: see text]CDM) model, a phenomenological emergent dark energy (PEDE) model and a model-independent quintessential parametrization (HBK). The bounds on the sum of neutrino masses [Formula: see text] depend on the dark energy (DE) models. In the HBK model, we confirm the conclusion from some previous work that the quintessence prior of DE tends to tighten the cosmological constraint on [Formula: see text]. On the other hand, the PEDE model leads to larger [Formula: see text] and a nonzero lower bound. Besides, we also explore the correlation between three different neutrino hierarchies and DE models.

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