Gamma-ray Bursts Hubble Diagram Research Articles

Interacting quintessence cosmology from Noether symmetries: Comparing theoretical predictions with observational data

In the framework of scalar-tensor gravity, we consider non-flat interacting quintessence cosmology where a scalar field is interacting with dark matter. Such a scalar field can be a standard or a phantom one. We use the Noether Symmetry Approach to obtain general exact solutions for cosmological equations and to select scalar-field self-interaction potentials. It turns out that the found solutions can reproduce the accelerated expansion of the Universe, and are compatible with observational dataset, as the SNeIa Pantheon data, gamma ray bursts Hubble diagram, and direct measurements of the Hubble parameter.

Testing dark energy models with gamma-ray bursts calibrated from the observationalH(z) data through a Gaussian process

ABSTRACTWe use a cosmology-independent method to calibrate gamma-ray burst (GRB) from the observational Hubble data (OHD) with the cosmic chronometer method. By using Gaussian process to reconstruct OHD, we calibrate the Amati relation (Ep–Eiso) to construct a GRB Hubble diagram with the A118 data set, and constrain dark energy models in a flat space with the Markov chain Monte Carlo numerical method. With the cosmology-independent GRBs at 1.4 < z ≤ 8.2 in the A118 data set and the Pantheon sample of Type Ia supernovae at 0.01 < z ≤ 2.3, we obtained Ωm = $0.379^{+0.033}_{-0.024}$, h = $0.701^{+0.0035}_{-0.0035}$, w = $-1.25^{+0.14}_{-0.12}$, and wa = $-0.84^{+0.81}_{-0.38}$ for the flat Chevallier–Polarski–Linder model at the 1σ confidence level. We find no significant evidence supporting deviations from the standard Lambda cold dark matter model.

Gamma-Ray Burst Constraints on Cosmological Models from the Improved Amati Correlation

An improved Amati correlation was constructed in ApJ 931 (2022) 50 by us recently. In this paper, we further study constraints on the ΛCDM and wCDM models from the gamma-ray bursts (GRBs) standardized with the standard and improved Amati correlations, respectively. By using the Pantheon Type Ia supernova sample to calibrate the latest A220 GRB data set, the GRB Hubble diagram is obtained model-independently. We find that at the high-redshift region (z > 1.4) the GRB distance modulus from the improved Amati correlation is larger apparently than that from the standard Amati one. The GRB data from the standard Amati correlation only give a lower bound limit on the present matter density parameter Ωm0, while the GRBs from the improved Amati correlation constrain the Ωm0 with the 68% confidence level to be and in the ΛCDM and wCDM models, respectively, which are very consistent with those given by other current popular observational data including baryon acoustic oscillation, cosmic microwave background (CMB) radiation, and so on. Once the H(z) data are added in our analysis, the constraint on the Hubble constant H 0 can be achieved. We find that two different correlations provide slightly different H 0 results but the marginalized mean values seem to be close to that from the Planck 2018 CMB radiation observations.

Reconstructing the Hubble diagram of gamma-ray bursts using deep learning

ABSTRACT We calibrate the distance and reconstruct the Hubble diagram of gamma-ray bursts (GRBs) using deep learning. We construct an artificial neural network, which combines the recurrent neural network and Bayesian neural network, and train the network using the Pantheon compilation of Type-Ia supernovae. The trained network is used to calibrate the distance of 174 GRBs based on the Combo-relation. We verify that there is no evident redshift evolution of Combo-relation, and obtain the slope and intercept parameters, $\gamma =0.856^{+0.083}_{-0.078}$ and $\log A=49.661^{+0.199}_{-0.217}$, with an intrinsic scatter $\sigma _{\rm int}=0.228^{+0.041}_{-0.040}$. Our calibrating method is independent of cosmological model, thus the calibrated GRBs can be directly used to constrain cosmological parameters. It is shown that GRBs alone can tightly constrain the ΛCDM model, with $\Omega _{\rm M}=0.280^{+0.049}_{-0.057}$. However, the constraint on the ωCDM model is relatively looser, with $\Omega _{\rm M}=0.345^{+0.059}_{-0.060}$ and ω < −1.414. The combination of GRBs and Pantheon can tightly constrain the ωCDM model, with $\Omega _{\rm M}=0.336^{+0.055}_{-0.050}$ and $\omega =-1.141^{+0.156}_{-0.135}$.

Prospects of high redshift constraints on dark energy models with the Ep, i − Eiso correlation in long gamma ray bursts

ABSTRACT So far large and different data sets revealed the accelerated expansion rate of the Universe, which is usually explained in terms of dark energy. The nature of dark energy is not yet known, and several models have been introduced: a non-zero cosmological constant, a potential energy of some scalar field, effects related to the non-homogeneous distribution of matter, or effects due to alternative theories of gravity. Recently, a tension with the flat ΛCDM model has been discovered using a high-redshift Hubble diagram of supernovae, quasars, and gamma-ray bursts (GRB). Here we use the Union2 type Ia supernovae and GRB Hubble diagram, and a set of direct measurements of the Hubble parameter to explore different dark energy models. We use the Chevallier–Polarski–Linder parametrization of the dark energy equation of state, a minimally coupled quintessence scalar field, and, finally, we consider models with dark energy at early times. We perform a statistical analysis based on the Markov chain Monte Carlo method, and explore the probability distributions of the cosmological parameters for each of the competing models. We apply the Akaike Information Criterion to compare these models: our analysis indicates that an evolving dark energy, described by a scalar field with exponential potential seems to be favoured by observational data.

Testing late-time cosmic acceleration with uncorrelated baryon acoustic oscillation dataset

Baryon acoustic oscillations (BAO) involve measuring the spatial distribution of galaxies to determine the growth rate of cosmic structures. We derive constraints on cosmological parameters from 17 uncorrelated BAO measurements that were collected from 333 published data points in the effective redshift range 0.106 ≤ z ≤ 2.36. We test the correlation of the subset using a random covariance matrix. The Λ cold dark matter (ΛCDM) model fit yields the cosmological parameters Ωm = 0.261 ± 0.028 and ΩΛ = 0.733 ± 0.021. Combining the BAO data with the Cosmic Chronometers data, the Pantheon type Ia supernova, and the Hubble diagram of gamma-ray bursts and quasars, the Hubble constant yields 69.85 ± 1.27 km s−1Mpc−1and the sound horizon distance gives 146.1 ± 2.15 Mpc. Beyond the ΛCDM model we test ΩkCDM andwCDM. The spatial curvature is Ωk = −0.076 ± 0.012 and the dark energy equation of states isw = −0.989 ± 0.049. We perform the Akaike information criteria test to compare the three models, and see that ΛCDM scores best.

High-redshift long gamma-ray bursts Hubble diagram as a test of basic cosmological relations

ABSTRACT We examine the prospects of the high-redshift long gamma-ray bursts (LGRBs) Hubble diagram as a test of the basic cosmological principles. Analysis of the Hubble diagram allows us to test several fundamental cosmological principles using the directly observed flux–distance–redshift relation. Modern LGRBs data together with the correlation between the spectral peak energy and the isotropic equivalent radiated energy (the so-called Amati relation) can be used for construction of the Hubble diagram at the model-independent level. We emphasize observational selection effects, which inevitably exist and distort the theoretically predicted relations. An example is the weak and strong gravitational lensing bias effect for high-redshift LGRB in the presence of limited observational sensitivity (Malmquist bias). After bias correction, there is a tendency to vacuum-dominated models with $\Omega _\Lambda \rightarrow 0.9$, Ωm → 0.1. Forthcoming gamma-ray observations by the Transient High-Energy Sky and Early Universe Surveyor (THESEUS) space mission together with ground- and space-based multimessenger facilities will allow us to improve essentially the restrictions on alternative basic principles of cosmological models.

Cosmology with gamma-ray bursts

Context. Explaining the accelerated expansion of the Universe is one of the fundamental challenges in physics today. Cosmography provides information about the evolution of the universe derived from measured distances, assuming only that the space time ge- ometry is described by the Friedman-Lemaitre-Robertson-Walker metric, and adopting an approach that effectively uses only Taylor expansions of basic observables. Aims. We perform a high-redshift analysis to constrain the cosmographic expansion up to the fifth order. It is based on the Union2 type Ia supernovae data set, the gamma-ray burst Hubble diagram, a data set of 28 independent measurements of the Hubble param- eter, baryon acoustic oscillations measurements from galaxy clustering and the Lyman-{\alpha} forest in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and some Gaussian priors on h and {\Omega}M . Methods. We performed a statistical analysis and explored the probability distributions of the cosmographic parameters. By building up their regions of confidence, we maximized our likelihood function using the Markov chain Monte Carlo method. Results. Our high-redshift analysis confirms that the expansion of the Universe currently accelerates; the estimation of the jerk parameter indicates a possible deviation from the standard {\Lambda}CDM cosmological model. Moreover, we investigate implications of our results for the reconstruction of the dark energy equation of state (EOS) by comparing the standard technique of cosmography with an alternative approach based on generalized Pad\'e approximations of the same observables. Because these expansions converge better, is possible to improve the constraints on the cosmographic parameters and also on the dark matter EOS. Conclusions. The estimation of the jerk and the DE parameters indicates at 1{\sigma} a possible deviation from the {\Lambda}CDM cosmological model.

Effect of gamma-ray burst (GRB) spectra on the empirical luminosity correlations and the GRB Hubble diagram

The spectra of gamma-ray bursts (GRBs) in a wide energy range can usually be well described by the Band function, which is a two smoothly jointed power laws cutting at a breaking energy. Below the breaking energy, the Band function reduces to a cut-off power law, while above the breaking energy it is a simple power law. However, for some detectors (such as the Swift-BAT) whose working energy is well below or just near the breaking energy, the observed spectra can be fitted to cut-off power law with enough precision. Besides, since the energy band of Swift-BAT is very narrow, the spectra of most GRBs can be fitted well even using a simple power law. In this paper, with the most up-to-date sample of Swift-BAT GRBs, we study the effect of different spectral models on the empirical luminosity correlations, and further investigate the effect on the reconstruction of GRB Hubble diagram. We mainly focus on two luminosity correlations, i.e., the Amati relation and Yonetoku relation. We calculate these two luminosity correlations on both the case that the GRB spectra are modeled by Band function and cut-off power law. It is found that both luminosity correlations only moderately depend on the choice of GRB spectra. Monte Carlo simulations show that Amati relation is insensitive to the high-energy power-law index of the Band function. As a result, the GRB Hubble diagram calibrated using luminosity correlations is almost independent on the GRB spectra.

Hints for families of gamma-ray bursts improving the Hubble diagram

As soon as their extragalactic origins were established, the hope to make Gamma - Ray Bursts (GRBs) standardizeable candles to probe the very high - z universe has opened the search for scaling relations between redshift independent observable quantities and distance dependent ones. Although some remarkable success has been achieved, the empirical correlations thus found are still affected by a significant intrinsic scatter which downgrades the precision in the inferred GRBs Hubble diagram. We investigate here whether this scatter may come from fitting together objects belonging to intrinsically different classes. To this end, we rely on a cladistics analysis to partition GRBs in homogenous families according to their rest frame properties. Although the poor statistics prevent us from drawing a definitive answer, we find that both the intrinsic scatter and the coefficients of the $E_{peak}$\,-\,$E_{iso}$ and $E_{peak}$\,-\,$L$ correlations significantly change depending on which subsample is fitted. It turns out that the fit to the full sample leads to a scaling relation which approximately follows the diagonal of the region delimited by the fits to each homogenous class. We therefore argue that a preliminary identification of the class a GRB belongs to is necessary in order to select the right scaling relation to be used in order to not bias the distance determination and hence the Hubble diagram.

THE GAMMA-RAY BURST HUBBLE DIAGRAM AND ITS IMPLICATIONS FOR COSMOLOGY

In this paper, we continue to build support for the proposal to use gamma-ray bursts (GRBs) as standard candles in constructing the Hubble Diagram at redshifts beyond the current reach of Type Ia supernova observations. We confirm that correlations among certain spectral and lightcurve features can indeed be used as luminosity indicators, and demonstrate from the most up-to-date GRB sample appropriate for this work that the $\Lambda$CDM model optimized with these data is characterized by parameter values consistent with those in the concordance model. Specifically, we find that $(\Omega_m,\Omega_\Lambda)\approx (0.25_{-0.06}^{+0.05}, 0.75_{-0.05}^{+0.06})$, which are consistent, to within $1\sigma$, with $(0.29,0.71)$ obtained from the 9-yr WMAP data. We also carry out a comparative analysis between $\Lambda$CDM and the $R_{\rm h}=ct$ Universe and find that the optimal $\Lambda$CDM model fits the GRB Hubble Diagram with a reduced $\chi^2_{\rm dof}\approx 2.26$, whereas the fit using $R_{\rm h}=ct$ results in a $\chi^2_{\rm dof}\approx 2.14$. In both cases, about 20% of the events lie at least $2\sigma$ away from the best-fit curves, suggesting that either some contamination by non-standard GRB luminosities is unavoidable, or that the errors and intrinsic scatter associated with the data are being underestimated. With these optimized fits, we use three statistical tools---the Akaike Information Criterion (AIC), the Kullback Information Criterion (KIC), and the Bayes Information Criterion (BIC)---to show that, based on the GRB Hubble Diagram, the likelihood of $R_{\rm h}=ct$ being closer to the correct model is $\sim 85-96%$, compared to $\sim 4-15%$ for $\Lambda$CDM.

A matter-dominated cosmological model with variable G and Λ and its confrontation with observational data

In the framework of renormalization-group improved cosmologies, we analyze both theoretically and observationally the exact and general solution of the matter-dominated cosmological equations, using the expression of \Lambda = \Lambda(G) already determined by the integration method employed in a previous paper. A rough comparison between such a model and the concordance \LambdaCDM model as to the magnitude-redshift relationship has been already done, without showing any appreciable differences. We here perform a more refined study of how astrophysical data (Union2 set) on type-I supernovae, gamma ray bursts (in a sample calibrated in a model independent way with the SneIa dataset), and gas fraction in galaxy clusters (using a sample of Chandra measurements of the X-ray gas mass fraction) affect the model and constrain its parameters. We also apply a cosmographic approach to our cosmological model and estimate the cosmographic parameters by fitting both the supernovae and the gamma ray bursts datasets. We show that this matter-dominated cosmological model with variable Newton parameter and variable cosmological term is indeed compatible with the observations above (on type Ia supernovae, the gamma ray bursts Hubble diagram, and the gas mass fraction in X-ray luminous galaxy clusters). The cosmographic approach adopted confirms such conclusions. Finally, it seems possible to include radiation into the model, since numerical integration of the equations derived by the presence of both radiation and matter shows that, after inflation, the total density parameter is initially dominated by the radiation contribution and later by the matter one.

The gamma-ray bursts Hubble diagram in quintessential cosmological models

It has been recently empirically established that some of the directly observed pa- rameters of GRBs are correlated with their important intrinsic parameters, like the luminosity or the total radiated energy. These correlations were derived, tested and used to standardize GRBs, i.e., to derive their luminosity or radiated energy from one or more observables, in order to construct an estimated fiducial Hubble diagram, assuming that radiation propagates in the standard LambdaCDM cosmological model. We extend these analyses by considering more general models of dark energy, and an updated data set of high redshift GRBs. We show that the correlation parameters only weakly depend on the cosmological model. Moreover we apply a local regression technique to estimate, in a model independent way, the distance modulus from the recently updated SNIa sample containing 307 SNIa (Astier et al. 2006), in order to calibrate the GRBs 2D correlations, considering only GRBs with z <1.4. The derived calibration parameters are used to construct a new GRBs Hubble diagram, which we call the calibrated GRBs HD. We also compare the estimated and calibrated GRBs HDs. It turns out that for the common GRBs they are fully statistically consistent, thus indicating that both of them are not affected by any systematic bias induced by the different standardizing procedures. We finally apply our methods to calibrate 95 long GRBs with the well-known Amati relation and construct the estimated and calibrated GRBs Hubble diagram that extends to redshifts z ~ 8. Even in this case there is consistency between these datasets. This means that the high redshift GRBs can be used to test different models of dark energy. We used the calibrated GRBs HD to constrain our quintessential cosmological model and derived the likelihood values of Omega_m and w(0).

An updated gamma-ray bursts Hubble diagram

Gamma ray bursts (GRBs) have recently attracted much attention as a possible way to extend the Hubble diagram to very high redshift. To this aim, the luminosity (or isotropic emitted energy) of a GRB at redshift z must be evaluated from a correlation with a distance independent quantity so that one can then solve for the luminosity distance D_L(z) and hence the distance modulus mu(z). Averaging over five different two parameters correlations and using a fiducial cosmological model to calibrate them, Schaefer (2007) has compiled a sample of 69 GRBs with measured mu(z) which has since then been widely used to constrain cosmological parameters. We update here that sample by many aspects. First, we add a recently found correlation for the X - ray afterglow and use a Bayesian inspired fitting method to calibrate the different GRBs correlations known insofar assuming a fiducial LCDM model in agreement with the recent WMAP5 data. Averaging over six correlations, we end with a new GRBs Hubble diagram comprising 83 objects. We also extensively explore the impact of varying the fiducial cosmological model considering how the estimated mu(z) change as a function of the $(\Omega_M, w_0, w_a)$ parameters of the Chevallier - Polarski - Linder phenomenological dark energy equation of state. In order to avoid the need of assuming an {\it a priori} cosmological model, we present a new calibration procedure based on a model independent local regression estimate of mu(z) using the Union SNeIa sample to calibrate the GRBs correlations. This finally gives us a GRBs Hubble diagram made out of 69 GRBs whose estimated distance modulus mu(z) is almost independent on the underlying cosmological model.

Constraints on generalized Chaplygin gas model including gamma-ray bursts

Generalized Chaplygin gas (whose equation of state is ) was proposed as a candidate for unification of dark energy and dark matter. We investigate constraints on this model with the latest observed data. We test the model with type-Ia supernovae (SNe Ia), cosmic microwave background (CMB) anisotropy, X-ray gas mass fractions in clusters, and gamma-ray bursts (GRBs). We calibrate the GRB luminosity relations without assuming any cosmological models using SNe Ia. We show that GRBs can extend the Hubble diagram to higher redshifts (z > 6). The GRB Hubble diagram is well behaved and delineates the shape of the Hubble diagram well. We measure (where ρGCG,0 is the energy density today) and at the 1σ confidence level using all the datasets. Our results rule out the standard Chaplygin gas model (α = 1) at the 3σ confidence level. The ΛCDM is allowed at the 2σ confidence level. We find that acceleration could have started at a redshift of z ∼ 0.70. The concordance of the generalized Chaplygin gas model with the age estimate of an old high redshift quasar is found. In addition, we show that GRBs can break the degeneracy between the generalized Chaplygin gas model and the XCDM model.

A Cosmology‐Independent Calibration of Gamma‐Ray Burst Luminosity Relations and the Hubble Diagram

An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient low-redshift GRB sample. In this paper, we present a new method to calibrate GRB relations in a cosmology-independent way. Since objects at the same redshift should have the same luminosity distance, and since the distance moduli of Type Ia supernovae (SNe Ia) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a GRB at a given redshift by interpolating from the Hubble diagram of SNe Ia. Then we calibrate seven GRB relations without assuming a particular cosmological model and construct a GRB Hubble diagram to constrain cosmological parameters. From the 42 GRBs at 1: 4 < z <= 6: 6, we obtain Omega(M) = 0.25(-0.05)(+0.04), Omega(Lambda) = 0.75(-0.04)(+0.05) for the flat Lambda CDM model, and for the dark energy model with a constant equation of state w(0) = -1.05(-0.40)(+0.27), which is consistent with the concordance model in a 1 sigma confidence region.

Confronting the Hubble diagram of gamma-ray bursts with Cardassian cosmology

We construct the Hubble diagram of gamma-ray bursts (GRBs) with redshifts reaching up toz∼6, by using five luminosity versus luminosity indicator relations calibrated with theCardassian cosmology. This model has a major interesting feature: despite being matterdominated and flat, it can explain the present accelerated expansion of the universe. This isthe first study of this class of models using high redshift GRBs. We have performed aχ squared statistical analysis of the GRBs calibrated with the Cardassian model, and alsocombined them with both the current cosmic microwave background and baryonic acousticoscillation data. Our results show consistency between the current observational data andthe model predictions; in particular, the best fit parameters obtained from thatχ2 analysis are in agreement with those obtained from previous investigations. The influence of these bestfit parameters on the redshift at which the universe would start to follow the Cardassian expansion,i.e., zcard, and on both the redshift at which the universe supposedly had started to accelerate, i.e.,zacc, and theage–redshift relation, H0t0, are also discussed. Our results also show that the universe, from the pointof view of GRBs, had undergone a transition to acceleration at a redshiftz≈0.2–0.7, which agrees with the type Ia supernovae results. One important point that wenotice is that despite the statistical analysis being performed with a model thatdoes not need any vacuum energy, we found that the results attained using thiscosmological model are compatible with those obtained with the concordance cosmology(Λ-CDM; CDM: cold dark matter), as far as GRBs are concerned. Hence, after confrontingthe Cardassian scenario with the GRB Hubble diagram, our main conclusion is that GRBsshould indeed be considered a tool complementary to several other observational studies fordoing precision cosmology.

Generalized Tests for Eight GRB Luminosity Relations

Long duration Gamma-Ray Bursts (GRBs) have eight luminosity relations where observable burst properties can yield the burst luminosity and hence distance. This turns GRBs into useful tools of cosmology. Recently, two tests have been proposed (by Nakar & Piran and by Li) for which one of the eight relations is claimed to have significant problems. In this paper, we generalize these tests and apply them to all eight GRB luminosity relations. (a) All eight relations pass the Nakar & Piran test after accounting for the uncertainties on the data and the dispersions of the correlations. (b) All eight relations are good when the GRB redshifts are known, for example for calibration of the relations and for GRB Hubble diagram purposes. (c) We confirm the earlier results that the E_gamma,iso - E_peak Amati relation must produce very large error bars whenever an unknown redshift being sought is >1.4. (d) The E_gamma - E_peak relation of Ghirlanda et al. must produce very large error bars whenever an unknown redshift being sought is >3.4. (e) The other six relations have no problem at all from the ambiguity test of Li.

Explaining the Gamma‐Ray Burst Lag/Luminosity Relation

The spectral lag of a gamma-ray burst (i.e., the cross-correlation delay between the light curves as measured at ~200 and 30 keV) is inversely related to the burst's peak luminosity. This lag/luminosity relation has passed three stiff predictions, so we have good empirical evidence for its validity. The relation is of high importance, since it provides a means to get the distances to bursts from the gamma-ray light curves alone, thus opening up the entire BATSE database to demographic studies, as well as making bursts available as tools for cosmology, even out to very high redshifts. Nevertheless, it would be good to have some theoretical understanding of why the lag is related to the luminosity. In this paper the lag/luminosity relation is shown to be a simple and forced consequence of the empirical and general Liang-Kargatis relation (which describes how the peak photon energy in the spectrum changes with time). In short, the lag is related to the time it takes for a pulse to cool somewhat (by ~6 keV); if the burst is highly luminous, then the cooling time (and hence the lag) will be short, while if the burst has a low luminosity, then the cooling time and lag will be long. With this understanding I propose three methods to improve the scatter in the lag/luminosity relation, and I note that there is no apparent cause for evolution to distort the gamma-ray burst Hubble diagram at high redshift.

Gamma-Ray Burst Hubble Diagram to [CLC][ITAL]z[/ITAL][/CLC] = 4.5

Gamma-ray bursts (GRBs) are tremendous explosions visible across most of the universe, certainly out to redshifts of z = 4.5 and likely out to z ~ 10. Recently, GRBs have been found to have a roughly constant explosive energy as well as to have two luminosity indicators (the spectral lag time and the variability) that can be used to derive the burst's luminosity distance from the gamma-ray light curve alone. There currently exists enough information to calibrate luminosity distances and independent redshifts for nine bursts. From these, a GRB Hubble diagram can be constructed, in which the observed shape of the curve provides a record of the expansion history of our universe. The current nine-burst diagram is sparse, yet formal limits can be placed on the mass density of a flat universe. This first GRB Hubble diagram provides a proof of concept for a new technique in cosmology at very high redshifts. With the launch of the Swift satellite in 2003, we should get ~120 bursts to produce a Hubble diagram impervious to all effects of dust extinction and out to redshifts impossible to reach by any other method.