Some recent developments(accelerated expansion)in the Universe cannot be explained by the conventional formulation of general relativity.We apply the recently proposed f(T,B)gravity to investigate the accelerated expa...Some recent developments(accelerated expansion)in the Universe cannot be explained by the conventional formulation of general relativity.We apply the recently proposed f(T,B)gravity to investigate the accelerated expansion of the Universe.By parametrizing the Hubble parameter and estimating the best fit values of the model parameters b_(0),b_(1),and b_(2)imposed from Supernovae type la,Cosmic Microwave Background,B aryon Acoustic Oscillation,and Hubble data using the Markov Chain Monte Carlo method,we propose a method to determine the precise solutions to the field equations.We then observe that the model appears to be in good agreement with the observations.A change from the deceleration to the acceleration phase of the Universe is shown by the evolution of the deceleration parameter.In addition,we investigate the behavior of the statefinder analysis,equation of state(EoS)parameters,along with the energy conditions.Furthermore,to discuss other cosmological parameters,we consider some wellknown f(T,B)gravity models,specifically,f(T,B)=aT^(b)+cB^(d).Lastly,we find that the considered f(T,B)gravity models predict that the present Universe is accelerating and the EoS parameter behaves like the ACDM model.展开更多
In this paper,we use genetic algorithms,a specific machine learning technique,to achieve a model-independent reconstruction of f(T)gravity.By using H(z)data derived from cosmic chronometers and the radial Baryon Acous...In this paper,we use genetic algorithms,a specific machine learning technique,to achieve a model-independent reconstruction of f(T)gravity.By using H(z)data derived from cosmic chronometers and the radial Baryon Acoustic Oscillation method,including the latest Dark Energy Spectroscopic Instrument(DESI)data,we reconstruct the Hubble rate,which is the basis parameter for reconstructing f(T)gravity without any assumptions.In this reconstruction process,we use the current value of the Hubble rate,H_(0),derived by genetic algorithms.The reconstructed f(T)function is consistent with the standardΛCDM cosmology within the 1 confidence level across a broad temporal range.The mean f(T)curve,adopting a quadratic form,prompts us to parametrize it using a second-degree polynomial.This quadratic deviation from theΛCDM scenario is mildly favored by the data.展开更多
The accelerated expansion of the Universe has sparked significant interest in the mysterious concept of dark energy within cosmology.Various theories have been proposed to explain dark energy,and many models have been...The accelerated expansion of the Universe has sparked significant interest in the mysterious concept of dark energy within cosmology.Various theories have been proposed to explain dark energy,and many models have been developed to understand its origins and properties.This research explores cosmic expansion using the Polytropic Gas(PG)approach,which combines Dark Matter(DM)and Dark Energy(DE)into a single mysterious fluid.We used the principles of general relativity and built our model within the homogeneous and isotropic framework of Friedmann-Lemaître-Robertson-Walker(FLRW)spacetime.We revised the Original Polytropic Gas(OPG)model to expand its applicability beyond the OPG,to theΛCDM model.Our model's parameters were carefully adjusted to reflect key cosmological features of the variable PG approach.To validate our model,we performed a Markov chain Monte Carlo analysis using recent Supernova data from the Pantheon+survey,36 observational data points,162 Gamma-Ray Bursts,and 24 binned Quasars distance modulus data.The AIC and BIC criteria indicate that our model is slightly preferred over theΛCDM model based on observational data.We also tested our model with data,Supernova,Gamma-Ray Bursts,and Quasars and found that it exhibits a transition from a quintessential to phantom regime.The Polytropic dark fluid model(PDFM)is a promising candidate that effectively addresses the interplay between cosmic acceleration and dark energy.展开更多
In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the ...In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the scalar field.Furthermore,the background and perturbative parameters are obtained by means of Friedmann equations in the slow roll regime.The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters,e.g.,the scalar spectral index and tensor to scalar ratio r.From this perspective,as an application of our analysis,we consider the Higgs field with quartic potential,which plays the inflaton role,and show that predictions of Higgs hybrid inflation are in good agreement with recent observational data[Astron.Astrophys.641,61(2020)].展开更多
基金the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan provided funding for this study(Grant No.AP09058240)。
文摘Some recent developments(accelerated expansion)in the Universe cannot be explained by the conventional formulation of general relativity.We apply the recently proposed f(T,B)gravity to investigate the accelerated expansion of the Universe.By parametrizing the Hubble parameter and estimating the best fit values of the model parameters b_(0),b_(1),and b_(2)imposed from Supernovae type la,Cosmic Microwave Background,B aryon Acoustic Oscillation,and Hubble data using the Markov Chain Monte Carlo method,we propose a method to determine the precise solutions to the field equations.We then observe that the model appears to be in good agreement with the observations.A change from the deceleration to the acceleration phase of the Universe is shown by the evolution of the deceleration parameter.In addition,we investigate the behavior of the statefinder analysis,equation of state(EoS)parameters,along with the energy conditions.Furthermore,to discuss other cosmological parameters,we consider some wellknown f(T,B)gravity models,specifically,f(T,B)=aT^(b)+cB^(d).Lastly,we find that the considered f(T,B)gravity models predict that the present Universe is accelerating and the EoS parameter behaves like the ACDM model.
基金Supported by the“PhD-Associate Scholarship–PASS”grant(number 29 UMP2023)of the National Center for Scientific and Technical Research in Morocco。
文摘In this paper,we use genetic algorithms,a specific machine learning technique,to achieve a model-independent reconstruction of f(T)gravity.By using H(z)data derived from cosmic chronometers and the radial Baryon Acoustic Oscillation method,including the latest Dark Energy Spectroscopic Instrument(DESI)data,we reconstruct the Hubble rate,which is the basis parameter for reconstructing f(T)gravity without any assumptions.In this reconstruction process,we use the current value of the Hubble rate,H_(0),derived by genetic algorithms.The reconstructed f(T)function is consistent with the standardΛCDM cosmology within the 1 confidence level across a broad temporal range.The mean f(T)curve,adopting a quadratic form,prompts us to parametrize it using a second-degree polynomial.This quadratic deviation from theΛCDM scenario is mildly favored by the data.
文摘The accelerated expansion of the Universe has sparked significant interest in the mysterious concept of dark energy within cosmology.Various theories have been proposed to explain dark energy,and many models have been developed to understand its origins and properties.This research explores cosmic expansion using the Polytropic Gas(PG)approach,which combines Dark Matter(DM)and Dark Energy(DE)into a single mysterious fluid.We used the principles of general relativity and built our model within the homogeneous and isotropic framework of Friedmann-Lemaître-Robertson-Walker(FLRW)spacetime.We revised the Original Polytropic Gas(OPG)model to expand its applicability beyond the OPG,to theΛCDM model.Our model's parameters were carefully adjusted to reflect key cosmological features of the variable PG approach.To validate our model,we performed a Markov chain Monte Carlo analysis using recent Supernova data from the Pantheon+survey,36 observational data points,162 Gamma-Ray Bursts,and 24 binned Quasars distance modulus data.The AIC and BIC criteria indicate that our model is slightly preferred over theΛCDM model based on observational data.We also tested our model with data,Supernova,Gamma-Ray Bursts,and Quasars and found that it exhibits a transition from a quintessential to phantom regime.The Polytropic dark fluid model(PDFM)is a promising candidate that effectively addresses the interplay between cosmic acceleration and dark energy.
文摘In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the scalar field.Furthermore,the background and perturbative parameters are obtained by means of Friedmann equations in the slow roll regime.The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters,e.g.,the scalar spectral index and tensor to scalar ratio r.From this perspective,as an application of our analysis,we consider the Higgs field with quartic potential,which plays the inflaton role,and show that predictions of Higgs hybrid inflation are in good agreement with recent observational data[Astron.Astrophys.641,61(2020)].
