This research paper examines a cosmological model in flat space-time via f(R,G)gravity,where R and G are the Ricci scalar and Gauss-Bonnet invariant,respectively.Our model assumes that f(R,G)is an exponential function...This research paper examines a cosmological model in flat space-time via f(R,G)gravity,where R and G are the Ricci scalar and Gauss-Bonnet invariant,respectively.Our model assumes that f(R,G)is an exponential function of G combined with a linear combination of R.We scrutinize the observational limitations under a power law cosmology that relies on two parameters,the Hubble constant(Ho)and the deceleration parameter(q)utilizing the 57-point H(z)data,8-point BAO data,1701-point Pantheon+data,joint data of H(z)+Pantheon,and joint data of H(z)+BAO+Pantheon+.The outcomes for H_(0)and q are realistic within observational ranges.We also address energy conditions,Om(z)analysis,and cosmographical parameters such as jerk,lerk,and snap.Our estimate of Ho is remarkably consistent with various recent Planck Collaboration studies that utilize the ACDM model.According to our study,power law cosmology within the context of f(R,G)gravity provides the most comprehensive explanation of the important aspects of cosmic evolution.展开更多
In order to reveal the nature of dark matter,it is crucial to detect its non-gravitational interactions with the standard model particles.The traditional dark matter searches focused on the so-called weakly interactin...In order to reveal the nature of dark matter,it is crucial to detect its non-gravitational interactions with the standard model particles.The traditional dark matter searches focused on the so-called weakly interacting massive particles.However,this paradigm is strongly constrained by the null results of current experiments with high precision.Therefore there is a renewed interest of searches for heavy dark matter particles above TeV scale.The Large High Altitude Air Shower Observatory(LHAASO)with large effective area and strong background rejection power is very suitable to investigate the gamma-ray signals induced by dark matter annihilation or decay above TeV scale.In this document,we review the theoretical motivations and background of heavy dark matter.We review the prospects of searching for the gamma-ray signals resulted from dark matter in the dwarf spheroidal satellites and Galactic halo for LHAASO,and present the projected sensitivities.We also review the prospects of searching for the axion-like particles,which are a kind of well motivated light pseudo-scalars,through the LHAASO measurement of the very high energy gamma-ray spectra of astrophysical sources.展开更多
Several pulsar timing array(PTA) collaborations have recently reported the evidence for a stochastic gravitational-wave background(SGWB), which can unveil the formation of primordial seeds of inhomogeneities in the ea...Several pulsar timing array(PTA) collaborations have recently reported the evidence for a stochastic gravitational-wave background(SGWB), which can unveil the formation of primordial seeds of inhomogeneities in the early universe. With the SGWB parameters inferred from PTAs data, we can make a prediction of the seeds for early galaxy formation from the domain walls in the axion-like particles(ALPs) field distribution. This also naturally provides a solution to the observation of high redshifts by the James Webb Space Telescope. The predicted photon coupling of the ALP is within the reach of future experimental searches.展开更多
基金support of the Ministry of Science and Higher Education of the Russian Federation(State contract GZ0110/23-10-IF)。
文摘This research paper examines a cosmological model in flat space-time via f(R,G)gravity,where R and G are the Ricci scalar and Gauss-Bonnet invariant,respectively.Our model assumes that f(R,G)is an exponential function of G combined with a linear combination of R.We scrutinize the observational limitations under a power law cosmology that relies on two parameters,the Hubble constant(Ho)and the deceleration parameter(q)utilizing the 57-point H(z)data,8-point BAO data,1701-point Pantheon+data,joint data of H(z)+Pantheon,and joint data of H(z)+BAO+Pantheon+.The outcomes for H_(0)and q are realistic within observational ranges.We also address energy conditions,Om(z)analysis,and cosmographical parameters such as jerk,lerk,and snap.Our estimate of Ho is remarkably consistent with various recent Planck Collaboration studies that utilize the ACDM model.According to our study,power law cosmology within the context of f(R,G)gravity provides the most comprehensive explanation of the important aspects of cosmic evolution.
文摘In order to reveal the nature of dark matter,it is crucial to detect its non-gravitational interactions with the standard model particles.The traditional dark matter searches focused on the so-called weakly interacting massive particles.However,this paradigm is strongly constrained by the null results of current experiments with high precision.Therefore there is a renewed interest of searches for heavy dark matter particles above TeV scale.The Large High Altitude Air Shower Observatory(LHAASO)with large effective area and strong background rejection power is very suitable to investigate the gamma-ray signals induced by dark matter annihilation or decay above TeV scale.In this document,we review the theoretical motivations and background of heavy dark matter.We review the prospects of searching for the gamma-ray signals resulted from dark matter in the dwarf spheroidal satellites and Galactic halo for LHAASO,and present the projected sensitivities.We also review the prospects of searching for the axion-like particles,which are a kind of well motivated light pseudo-scalars,through the LHAASO measurement of the very high energy gamma-ray spectra of astrophysical sources.
基金supported by the National Natural Science Foundation of China (Grant Nos.12275134,12147228,12335005,and 12275232)by Maxim Khlopov was carried out at Southern Federal University with financial support from the Ministry of Science and Higher Education of the Russian Federation (Grant No.GZ0110/2310-IF)+2 种基金supported by the National Natural Science Foundation of China (Grant Nos.12005180,and 12305113)the Natural Science Foundation of Shandong Province (Grant Nos.ZR2020QA083,and ZR2022QA026)the Project of Shandong Province Higher Educational Science and Technology Program (Grant No.2022KJ271)。
文摘Several pulsar timing array(PTA) collaborations have recently reported the evidence for a stochastic gravitational-wave background(SGWB), which can unveil the formation of primordial seeds of inhomogeneities in the early universe. With the SGWB parameters inferred from PTAs data, we can make a prediction of the seeds for early galaxy formation from the domain walls in the axion-like particles(ALPs) field distribution. This also naturally provides a solution to the observation of high redshifts by the James Webb Space Telescope. The predicted photon coupling of the ALP is within the reach of future experimental searches.
