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
We conduct an investigation to explore late-time cosmic acceleration through various dark energy parametrizations(Wettrich,Efstathiou,and Ma-Zhang)within the Horava-Lifshitz gravity framework.As an alternative to gene...We conduct an investigation to explore late-time cosmic acceleration through various dark energy parametrizations(Wettrich,Efstathiou,and Ma-Zhang)within the Horava-Lifshitz gravity framework.As an alternative to general relativity,this theory introduces anisotropic scaling at ultraviolet scales.Our primary objective is to constrain the key cosmic parameters and baryon acoustic oscillation(BAO)scale,specifically the sound horizon(rd),by utilizing 24 uncorrelated measurements of BAOs derived from recent galaxy surveys spanning a redshift range from z=0.106 to z=2.33.Additionally,we integrate the most recent Hubble constant measurement by Riess in 2022(denoted as R22)as an extra prior.For the parametrizations of Wettrich,Efstathiou,and Ma-Zhang,our analysis of BAO data yields sound horizon results of r_(d)=148.1560±2.7688 Mpc,r_(d)=148.6168±10.2469 Mpc,and r_(d)=147.9737±10.6096 Mpc,respectively.Incorporating the R22 prior into the BAO dataset results in r_(d)=139.5806±3.8522 Mpc,r_(d)=139.728025±2.7858 Mpc,and r_(d)=139.6001±2.7441 Mpc.These outcomes highlight a distinct inconsistency between early and late observational measurements,analogous to the H_(0) tension.A notable observation is that,when we do not include the R22 prior,the outcomes for rd tend to be in agreement with Planck and SDSS results.Following this,we conducted a cosmography test and comparative study of each parametrization within the Lambda Cold Dark Matter paradigm.Our diagnostic analyses demonstrate that all models fit seamlessly within the phantom region.All dark energy parametrizations predict an equation of state parameter close ω=-1,indicating a behavior similar to that of a cosmological constant.The statistical analysis indicates that neither of the two models can be ruled out based on the latest observational measurements.展开更多
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We conduct an investigation to explore late-time cosmic acceleration through various dark energy parametrizations(Wettrich,Efstathiou,and Ma-Zhang)within the Horava-Lifshitz gravity framework.As an alternative to general relativity,this theory introduces anisotropic scaling at ultraviolet scales.Our primary objective is to constrain the key cosmic parameters and baryon acoustic oscillation(BAO)scale,specifically the sound horizon(rd),by utilizing 24 uncorrelated measurements of BAOs derived from recent galaxy surveys spanning a redshift range from z=0.106 to z=2.33.Additionally,we integrate the most recent Hubble constant measurement by Riess in 2022(denoted as R22)as an extra prior.For the parametrizations of Wettrich,Efstathiou,and Ma-Zhang,our analysis of BAO data yields sound horizon results of r_(d)=148.1560±2.7688 Mpc,r_(d)=148.6168±10.2469 Mpc,and r_(d)=147.9737±10.6096 Mpc,respectively.Incorporating the R22 prior into the BAO dataset results in r_(d)=139.5806±3.8522 Mpc,r_(d)=139.728025±2.7858 Mpc,and r_(d)=139.6001±2.7441 Mpc.These outcomes highlight a distinct inconsistency between early and late observational measurements,analogous to the H_(0) tension.A notable observation is that,when we do not include the R22 prior,the outcomes for rd tend to be in agreement with Planck and SDSS results.Following this,we conducted a cosmography test and comparative study of each parametrization within the Lambda Cold Dark Matter paradigm.Our diagnostic analyses demonstrate that all models fit seamlessly within the phantom region.All dark energy parametrizations predict an equation of state parameter close ω=-1,indicating a behavior similar to that of a cosmological constant.The statistical analysis indicates that neither of the two models can be ruled out based on the latest observational measurements.
