scholarly journals Constraints on cosmological parameters from gamma-ray burst peak photon energy and bolometric fluence measurements and other data

2020 ◽  
Vol 499 (1) ◽  
pp. 391-403 ◽  
Author(s):  
Narayan Khadka ◽  
Bharat Ratra
Keyword(s):  
Photon Energy ◽  
Hubble Parameter ◽  
Gamma Ray ◽  
Cosmological Parameters ◽  
Acoustic Oscillation ◽  
Cosmological Models ◽  
Gamma Ray Bursts ◽  
Joint Analysis ◽  
Baryon Acoustic Oscillation ◽  
Parameter Constraints

ABSTRACT We use measurements of the peak photon energy and bolometric fluence of 119 gamma-ray bursts (GRBs) extending over the redshift range of 0.3399 ≤ z ≤ 8.2 to simultaneously determine cosmological and Amati relation parameters in six different cosmological models. The resulting Amati relation parameters are almost identical in all six cosmological models, thus validating the use of the Amati relation in standardizing these GRBs. The GRB data cosmological parameter constraints are consistent with, but significantly less restrictive than, those obtained from a joint analysis of baryon acoustic oscillation and Hubble parameter measurements.

scholarly journals Quasar X-ray and UV flux, baryon acoustic oscillation, and Hubble parameter measurement constraints on cosmological model parameters

2020 ◽  
Vol 492 (3) ◽  
pp. 4456-4468 ◽  
Author(s):  
Narayan Khadka ◽  
Bharat Ratra
Keyword(s):  
Hubble Parameter ◽  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Acoustic Oscillation ◽  
Joint Analysis ◽  
Model Parameters ◽  
Baryon Acoustic Oscillation ◽  
Current Standard ◽  
X Ray ◽  
Flux Measurements

ABSTRACT We use the 2015 Risaliti and Lusso compilation of 808 X-ray and UV flux measurements of quasars (QSOs) in the redshift range 0.061 ≤ z ≤ 6.28, alone and in conjunction with baryon acoustic oscillation (BAO) and Hubble parameter [H(z)] measurements, to constrain cosmological parameters in six cosmological models. The QSO data constraints are significantly weaker than, but consistent with, those from the H(z) + BAO data. A joint analysis of the QSO + H(z) + BAO data is consistent with the current standard model, spatially flat Λ cold dark matter, but mildly favours closed spatial hypersurfaces and dynamical dark energy.

scholarly journals Towards a self-consistent analysis of the anisotropic galaxy two- and three-point correlation functions on large scales: application to mock galaxy catalogues

2020 ◽  
Author(s):  
Naonori S Sugiyama ◽  
Shun Saito ◽  
Florian Beutler ◽  
Hee-Jong Seo
Keyword(s):  
Correlation Functions ◽  
Hubble Parameter ◽  
Theoretical Models ◽  
Practical Method ◽  
Acoustic Oscillation ◽  
Nonlinear Damping ◽  
Joint Analysis ◽  
Angular Diameter Distance ◽  
Point Correlation ◽  
Parameter Constraints

Abstract We establish a practical method for the joint analysis of anisotropic galaxy two- and three-point correlation functions (2PCF and 3PCF) on the basis of the decomposition formalism of the 3PCF using tri-polar spherical harmonics. We perform such an analysis with MultiDark Patchy mock catalogues to demonstrate and understand the benefit of the anisotropic 3PCF. We focus on scales above 80 h−1 Mpc, and use information from the shape and the baryon acoustic oscillation (BAO) signals of the 2PCF and 3PCF. We also apply density field reconstruction to increase the signal-noise ratio of BAO in the 2PCF measurement, but not in the 3PCF measurement. In particular, we study in detail the constraints on the angular diameter distance and the Hubble parameter. We build a model of the bispectrum or 3PCF that includes the nonlinear damping of the BAO signal in redshift space. We carefully account for various uncertainties in our analysis including theoretical models of the 3PCF, window function corrections, biases in estimated parameters from the fiducial values, the number of mock realizations to estimate the covariance matrix, and bin size. The joint analysis of the 2PCF and 3PCF monopole and quadrupole components shows a $30\%$ and $20\%$ improvement in Hubble parameter constraints before and after reconstruction of the 2PCF measurements, respectively, compared to the 2PCF analysis alone. This study clearly shows that the anisotropic 3PCF increases cosmological information from galaxy surveys and encourages further development of the modeling of the 3PCF on smaller scales than we consider.

scholarly journals Using quasar X-ray and UV flux measurements to constrain cosmological model parameters

2020 ◽  
Vol 497 (1) ◽  
pp. 263-278 ◽  
Author(s):  
Narayan Khadka ◽  
Bharat Ratra
Keyword(s):  
Cosmological Parameters ◽  
Hubble Constant ◽  
Acoustic Oscillation ◽  
Joint Analysis ◽  
Model Parameters ◽  
Density Parameter ◽  
Current Standard ◽  
X Ray ◽  
Flux Measurements ◽  
Parameter Constraints

ABSTRACT Risaliti and Lusso have compiled X-ray and UV flux measurements of 1598 quasars (QSOs) in the redshift range 0.036 ≤ z ≤ 5.1003, part of which, z ∼ 2.4 − 5.1, is largely cosmologically unprobed. In this paper we use these QSO measurements, alone and in conjunction with baryon acoustic oscillation (BAO) and Hubble parameter [H(z)] measurements, to constrain cosmological parameters in six different cosmological models, each with two different Hubble constant priors. In most of these models, given the larger uncertainties, the QSO cosmological parameter constraints are mostly consistent with those from the BAO + H(z) data. A somewhat significant exception is the non-relativistic matter density parameter Ωm0 where QSO data favour Ωm0 ∼ 0.5 − 0.6 in most models. As a result, in joint analyses of QSO data with H(z) + BAO data the 1D Ωm0 distributions shift slightly towards larger values. A joint analysis of the QSO + BAO + H(z) data is consistent with the current standard model, spatially-flat ΛCDM, but mildly favours closed spatial hypersurfaces and dynamical dark energy. Since the higher Ωm0 values favoured by QSO data appear to be associated with the z ∼ 2 − 5 part of these data, and conflict somewhat with strong indications for Ωm0 ∼ 0.3 from most z < 2.5 data as well as from the cosmic microwave background anisotropy data at z ∼ 1100, in most models, the larger QSO data Ωm0 is possibly more indicative of an issue with the z ∼ 2 − 5 QSO data than of an inadequacy of the standard flat ΛCDM model.

scholarly journals COSMOLOGY WITH THE Ep,i – Eiso CORRELATION OF GAMMA–RAY BURSTS

2012 ◽  
Vol 12 ◽  
pp. 19-27 ◽  
Author(s):  
LORENZO AMATI
Keyword(s):  
Photon Energy ◽  
Energy Band ◽  
Gamma Ray ◽  
Cosmological Parameters ◽  
Gamma Ray Bursts ◽  
Spectral Peak ◽  
X Ray ◽  
Radiated Energy ◽  
The Universe

Gamma–Ray Bursts (GRBs) are the brightest sources in the universe, emit mostly in the hard X–ray energy band and have been detected at redshifts up to about 8.2. Thus, they are in principle very powerful probes for cosmology. I shortly review the researches aimed to use GRBs for the measurement of cosmological parameters, which are mainly based on the correlation between spectral peak photon energy and total radiated energy or luminosity. In particular, based on an enriched sample of 120 GRBs, I will provide an update of the analysis by Amati et al. (2008) aimed at extracting information on ΩM and, to a less extent, on ΩΛ, from the E p,i – E iso correlation.

scholarly journals The duration–photon energy relation in Gamma-Ray Bursts and its interpretations

1997 ◽  
Author(s):  
Demosthenes Kazanas ◽  
Lev G. Titarchuk ◽  
Xin-Min Hua
Keyword(s):  
Photon Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Energy Relation

scholarly journals Constraints on holographic cosmological models from gamma ray bursts

2016 ◽  
Vol 10 ◽  
pp. 33-43
Author(s):  
Alexander Bonilla Rivera ◽  
Jairo Ernesto Castillo Hernandez
Keyword(s):  
Gamma Ray ◽  
Cosmological Models ◽  
Gamma Ray Bursts
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