Identification of Two Categories of optically bright Gamma-Ray bursts and A Model-Independent Luminosity Indicator

2006 ◽  
Author(s):  
Enwei Liang
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Model Independent

scholarly journals Model-independent calibrations of gamma-ray bursts using machine learning

2021 ◽  
Vol 503 (3) ◽  
pp. 4581-4600
Author(s):  
Orlando Luongo ◽  
Marco Muccino
Keyword(s):  
Machine Learning ◽  
Dark Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Bayesian Regression ◽  
Machine Learning Techniques ◽  
Acoustic Oscillations ◽  
Chi Square ◽  
Model Independent ◽  
Chi Square Analysis

ABSTRACT We alleviate the circularity problem, whereby gamma-ray bursts are not perfect distance indicators, by means of a new model-independent technique based on Bézier polynomials. We use the well consolidate Amati and Combo correlations. We consider improved calibrated catalogues of mock data from differential Hubble rate points. To get our mock data, we use those machine learning scenarios that well adapt to gamma-ray bursts, discussing in detail how we handle small amounts of data from our machine learning techniques. We explore only three machine learning treatments, i.e. linear regression, neural network, and random forest, emphasizing quantitative statistical motivations behind these choices. Our calibration strategy consists in taking Hubble’s data, creating the mock compilation using machine learning and calibrating the aforementioned correlations through Bézier polynomials with a standard chi-square analysis first and then by means of a hierarchical Bayesian regression procedure. The corresponding catalogues, built up from the two correlations, have been used to constrain dark energy scenarios. We thus employ Markov chain Monte Carlo numerical analyses based on the most recent Pantheon supernova data, baryonic acoustic oscillations, and our gamma-ray burst data. We test the standard ΛCDM model and the Chevallier–Polarski–Linder parametrization. We discuss the recent H0 tension in view of our results. Moreover, we highlight a further severe tension over Ωm and we conclude that a slight evolving dark energy model is possible.

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.

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 Standardizing Dainotti-correlated gamma-ray bursts, and using them with standardized Amati-correlated gamma-ray bursts to constrain cosmological model parameters

2021 ◽  
Author(s):  
Shulei Cao ◽  
Narayan Khadka ◽  
Bharat Ratra
Keyword(s):  
Cosmological Model ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Model Parameters ◽  
Data Sets ◽  
Density Parameter ◽  
Cosmological Constraints ◽  
Cosmological Expansion ◽  
Model Independent ◽  
Lower Limits

Abstract We show that each of the three Dainotti-correlated gamma-ray burst (GRB) data sets recently compiled by Wang et al. and Hu et al., that together probe the redshift range 0.35 ≤ z ≤ 5.91, obey cosmological-model-independent Dainotti correlations and so are standardizable. We use these GRB data in conjunction with the best currently-available Amati-correlated GRB data, that probe 0.3399 ≤ z ≤ 8.2, to constrain cosmological model parameters. The resulting cosmological constraints are weak, providing lower limits on the non-relativistic matter density parameter, mildly favoring non-zero spatial curvature, and largely consistent with currently accelerated cosmological expansion as well as with constraints determined from better-established data.

scholarly journals Does $$\varLambda $$CDM really be in tension with the Hubble diagram data?

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Ahmad Mehrabi ◽  
Spyros Basilakos
Keyword(s):  
Gaussian Process ◽  
Gamma Ray ◽  
New Physics ◽  
Gamma Ray Bursts ◽  
Hubble Diagram ◽  
Type Ia ◽  
Model Independent ◽  
Supernovae Type Ia

Abstract In this article, we elaborate further on the $$\varLambda $$ΛCDM “tension”, suggested recently by the authors Lusso et al. (Astron Astrophys 628:L4, 2019) and Risaliti and Lusso (Nat Astron 3(3):272, 2019). We combine Supernovae type Ia (SNIa) with quasars (QSO) and Gamma Ray Bursts (GRB) data in order to reconstruct in a model independent way the Hubble relation to as high redshifts as possible. Specifically, in the case of either SNIa or SNIa/QSO data we find that the current values of the cosmokinetic parameters extracted from the Gaussian process are consistent with those of $$\varLambda $$ΛCDM. Including GRBs in the analysis we find a tension, which lies between $$2\sigma $$2σ and $$3\sigma $$3σ levels respectively. Finally, we find that at high redshifts ($$z>1$$z>1) the corresponding cosmokinetic parameters significantly deviate from those of $$\varLambda $$ΛCDM, hence the possibility of new Physics is not precluded by the present analysis.

scholarly journals Kinematic constraints beyond z ≃ 0 using calibrated GRB correlations

2020 ◽  
Vol 641 ◽  
pp. A174
Author(s):  
Orlando Luongo ◽  
Marco Muccino
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Systematic Errors ◽  
Gamma Ray Bursts ◽  
Auxiliary Variables ◽  
Confidence Levels ◽  
History Of ◽  
Standard Cosmological Model ◽  
Model Independent ◽  
The Universe

Context. The dynamics of the Universe are revised using high-redshift data from gamma-ray bursts to constrain cosmographic parameters by means of model-independent techniques. Aims. Considering samples from four gamma-ray burst correlations and two hierarchies up to j0 and s0, respectively, we derived limits over the expansion history of the Universe. Since cosmic data span outside z ≃ 0, we investigated additional cosmographic methods such as auxiliary variables and Padé approximations Methods. Beziér polynomials were employed to calibrate our correlations and heal the circularity problem. Several Markov chain Monte Carlo simulations were performed on the model-independently calibrated Amati, Ghirlanda, Yonetoku, and combo correlations to obtain 1 − σ and 2 − σ confidence levels and to test the standard cosmological model. Results. Reasonable results are found up to j0 and s0 hierarchies, respectively, only partially alleviating the tension on local H0 measurements as j0 hierarchy is considered. Discussions on systematic errors have been extensively reported here. Conclusions. Our findings show that the ΛCDM model is not fully confirmed using gamma-ray bursts. Indications against a genuine cosmological constant are summarized and commented on in detail.

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