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基于COSMIC掩星观测的顶部电离层标高特征分析
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作者 韩超 庞岗 +7 位作者 靳睿敏 甄卫民 王丹丹 马雪纯 朱庆林 陈龙江 陈丽 白培瑞 《电波科学学报》 CSCD 北大核心 2024年第2期253-261,共9页
顶部电离层是指F2层电子密度最大值所在高度以上的电离层区域。掩星观测能够提供地面到低轨卫星轨道高度处的整个电离层电子密度剖面,对于顶部电离层的研究具有重要作用。标高是构建顶部以上电离层电子密度剖面模型的重要参数。本文使用... 顶部电离层是指F2层电子密度最大值所在高度以上的电离层区域。掩星观测能够提供地面到低轨卫星轨道高度处的整个电离层电子密度剖面,对于顶部电离层的研究具有重要作用。标高是构建顶部以上电离层电子密度剖面模型的重要参数。本文使用2007—2020年的气象、电离层和气候星座观测系统(Constellation Observing System for Meteorology,Ionosphere and Climate,COSMIC)掩星观测数据,提取有效电子密度剖面数据的顶部标高,分析了其随地方时、季节、经纬度和太阳活动水平的变化特性。结果表明:顶部标高具有明显的日变化和季节变化规律,并且表现出强烈的太阳活动依赖性;顶部标高在纬度上的变化强烈依赖于地方时,同时在东西经向上表现出明显的波状结构,且这种经度波状结构在南北半球具有不同的形态;顶部标高在夏季半球具有显著的东西经向差异,南半球夏季更为明显。 展开更多
关键词 cosmic掩星 顶部电离层 电子密度剖面 太阳活动 标高
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COSMIC电离层掩星反演模拟及星座优化
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作者 许波波 王成 +3 位作者 张雨露 文援兰 何丽娜 李桢 《空间科学学报》 CAS CSCD 北大核心 2024年第1期71-79,共9页
基于卫星导航系统精密星历和NeQuick模型模拟COSMIC星座电离层掩星事件的几何过程和物理数据,并采用改正TEC法和“洋葱分层”算法反演电离层三维电子密度.模拟反演得到的电子密度廓线与模型变化趋势一致,偏差较小.电离层h_(m)F_(2),N_(m... 基于卫星导航系统精密星历和NeQuick模型模拟COSMIC星座电离层掩星事件的几何过程和物理数据,并采用改正TEC法和“洋葱分层”算法反演电离层三维电子密度.模拟反演得到的电子密度廓线与模型变化趋势一致,偏差较小.电离层h_(m)F_(2),N_(m)F_(2)的绝对误差分别为4.2 km和0.26×10^(4)cm^(–3),相对误差分别为1.66%和4.95%,反演值与模型值的线性回归决定系数R2分别为0.956和0.950,表明掩星反演模拟完整可靠、正确有效.在几何模拟正确的基础上,分析了COSMIC-2完全组网时的掩星观测性能及多系统GNSS对掩星数量及空间分布特征的影响.为提高未来掩星事件的时效性及时空分布的均匀性,提出了一种掩星分布均匀性指数,并且通过非支配排序遗传算法实现掩星星座卫星总数、轨道面数、轨道倾角的最优确定. 展开更多
关键词 cosmic 电离层 掩星反演 模拟 电子密度
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Classical Cosmology II. The Einstein Ring
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作者 Lorenzo Zaninetti 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第2期574-598,共25页
The Einstein ring is usually explained in the framework of the gravitational lens. Conversely here we apply the framework of the expansion of a superbubble (SB) in order to explain the spherical appearance of the ring... The Einstein ring is usually explained in the framework of the gravitational lens. Conversely here we apply the framework of the expansion of a superbubble (SB) in order to explain the spherical appearance of the ring. Two classical equations of motion for SBs are derived in the presence of a linear and a trigonometric decrease for density. A relativistic equation of motion with an inverse square dependence for the density is derived. The angular distance, adopting the minimax approximation, is derived for three relativistic cosmologies: the standard, the flat and the wCDM. We derive the relation between redshift and Euclidean distance, which allows fixing the radius of the Einstein ring. The details of the ring are explained by a simple version of the theory of images. 展开更多
关键词 cosmology Observational cosmology Gravitational Lenses Luminous Arcs
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Effect of Cosmic Plasma on the Observation of Supernovae Ia
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作者 Yi-Jia Zheng 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期46-49,共4页
In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la... In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la is dimmer than expected.This dimming effect is considered observational evidence for the existence of dark energy in the universe.It should be noted that this conclusion is based on an assumption that the mass density of the cosmic plasma is very small.Therefore,the dimming effect caused by the Compton scattering of free electrons in cosmic plasma can be neglected.X-ray observations suggest that the mass density of the cosmic plasma may be very large.In theory,the observed dimming effect of high redshift supernovae Ia may be caused by the Compton scattering of free electrons in the cosmic plasma.In this paper it will be shown that this idea is reasonable.Therefore,there is no need to introduce the confusing concept of dark energy into cosmology. 展开更多
关键词 cosmology-cosmology observations-cosmology theory-(cosmology:)dark energy-(cosmology:)listance scale-X-rays diffuse background-plasmas-opacity
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How the Flat Space Cosmology Model Correlates the Recombination CMB Temperature of 3000 K with a Redshift of 1100
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作者 Eugene Terry Tatum U. V. S. Seshavatharam 《Journal of Modern Physics》 2024年第2期174-178,共5页
This paper shows how the Flat Space Cosmology model correlates the recom-bination epoch CMB temperature of 3000 K with a cosmological redshift of 1100. This proof is given in support of the recent publication that the... This paper shows how the Flat Space Cosmology model correlates the recom-bination epoch CMB temperature of 3000 K with a cosmological redshift of 1100. This proof is given in support of the recent publication that the Tatum and Seshavatharam Hubble temperature formulae can be derived using the Stephan-Boltzmann dispersion law. Thus, as explained herein, the era of high precision Planck scale quantum cosmology has arrived. 展开更多
关键词 Hubble Constant cosmic Microwave Background Quantum cosmology Stephan-Boltzmann Upsilon Coupling Constant Flat Space cosmology ΛCDM cosmology
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Classical Cosmology I. Anomalous Redshift for Galaxies in NED-D
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作者 Lorenzo Zaninetti 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期8-26,共19页
Three mechanisms for an alternative to the Doppler effect as an explanation for the redshift are reviewed. A fourth mechanism is the attenuation of the light as given by the Beer-Lambert law. The average value of the ... Three mechanisms for an alternative to the Doppler effect as an explanation for the redshift are reviewed. A fourth mechanism is the attenuation of the light as given by the Beer-Lambert law. The average value of the Hubble constant is therefore derived by processing the galaxies of the NED-D catalog in which the distances are independent of the redshift. The observed anisotropy of the Hubble constant is reproduced by adopting a rim model, a chord model, and both 2D and 3D Voronoi diagrams. 展开更多
关键词 Galaxy Groups Clusters SUPERCLUSTERS Large Scale Structure of the Universe cosmology
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Upsilon Constants and Their Usefulness in Planck Scale Quantum Cosmology
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作者 Eugene Terry Tatum 《Journal of Modern Physics》 2024年第2期167-173,共7页
This paper introduces the two Upsilon constants to the reader. Their usefulness is described with respect to acting as coupling constants between the CMB temperature and the Hubble constant. In addition, this paper su... This paper introduces the two Upsilon constants to the reader. Their usefulness is described with respect to acting as coupling constants between the CMB temperature and the Hubble constant. In addition, this paper summarizes the current state of quantum cosmology with respect to the Flat Space Cosmology (FSC) model. Although the FSC quantum cosmology formulae were published in 2018, they are only rearrangements and substitutions of the other assumptions into the original FSC Hubble temperature formula. In a real sense, this temperature formula was the first quantum cosmology formula developed since Hawking’s black hole temperature formula. A recent development in the last month proves that the FSC Hubble temperature formula can be derived from the Stephan-Boltzmann law. Thus, this Hubble temperature formula effectively unites some quantum developments with the general relativity model inherent in FSC. More progress towards unification in the near-future is expected. 展开更多
关键词 Quantum cosmology Hubble Constant Planck Scale Upsilon Constant Flat Space cosmology Black Holes CMB Temperature ΛCDM cosmology Quantum Gravity Unification
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Transport in Astrophysics: VI. Ultra-High Energy Cosmic Rays
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作者 Lorenzo Zaninetti 《International Journal of Astronomy and Astrophysics》 2024年第1期65-84,共20页
Two new solutions of the homogeneous diffusion equation in 1D are derived in the presence of losses and a trigonometric profile for a profile of density. A simulation for the ankle in the energy distribution of cosmic... Two new solutions of the homogeneous diffusion equation in 1D are derived in the presence of losses and a trigonometric profile for a profile of density. A simulation for the ankle in the energy distribution of cosmic rays (CRs) is provided in the framework of the fine tuning of the involved parameters. A theoretical image for the overall diffusion of CRs in galactic coordinates is provided. 展开更多
关键词 cosmic Rays Particle Diffusion Random Walks
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The 111-Years-Old Cosmic Ray Puzzle Has Been Solved?
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作者 Shlomo Dado Arnon Dar 《Journal of Modern Physics》 2024年第1期125-131,共7页
We show that recently multi-messenger astronomy has provided compelling evidence that the bulk of high energy cosmic rays (CRs) are produced by highly relativistic narrow jets of plasmoids launched in core collapse of... We show that recently multi-messenger astronomy has provided compelling evidence that the bulk of high energy cosmic rays (CRs) are produced by highly relativistic narrow jets of plasmoids launched in core collapse of stripped-envelope massive stars to neutron stars and stellar mass black holes. Such events produce also a visible GRB if the jet happens to point in our direction. This has been long advocated by the cannon ball (CB) model of high energy CRs and GRBs, but the evidence has been provided only recently by what were widely believed to be unrelated discoveries. They include the very recent discovery of a knee around TeV in the energy spectrum of high energy CR electrons, the peak photon energy in the “brightest of all time” GRB221009A, and the failure of IceCube to detect high energy neutrinos from GRBs, including GRB221009A. They were all predicted by the cannonball (CB) model of high energy CRs and GRBs long before they were discovered in observations, despite a negligible probability to occur by chance. 展开更多
关键词 cosmic Rays Gamma Ray Bursts Neutrino Bursts
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Time Dilation Cosmology 2
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作者 Joseph H. (Cass) Forrington 《Journal of Modern Physics》 2024年第4期448-461,共14页
This paper is a further elaboration of the author’s Time Dilation Cosmology (TDC) holographic model that ties gravitation and celestial mechanics and kinematics directly to time dilation, resolving all the major conu... This paper is a further elaboration of the author’s Time Dilation Cosmology (TDC) holographic model that ties gravitation and celestial mechanics and kinematics directly to time dilation, resolving all the major conundrums in astrophysics, and ties astrophysics directly to quantum physics. It begins with a brief summary of the TDC model and contains the new derivation for the time dilation version of the formula for summing relativistic velocities, Einstein’s gravitational constant and the time dilation versions for the Lorentz factor and the Euclidean norm of the 3d velocity vector, the two of which can then be used in the Four-velocity formula. It is demonstrated how orbital curvature is manifested as the resultant of two time dilation-manifested velocities. It also explains why an interferometer cannot distinguish free fall from zero gravity and further elaborates on the author’s previous explanations of how spiral galaxies are formed, and contains mathematical proof that Black Holes are actually Magnetospheric Eternally Collapsing Objects (MECOs) that are massless spacetime vortices. 展开更多
关键词 GRAVITATION Time Time Dilation Celestial Mechanics ISM: Kinematics and Dynamics cosmology: Theory Galaxies: Evolution
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Ratio of Gravitational Force to Electric Force from Empirical Equations in Terms of the Cosmic Microwave Background Temperature
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作者 Tomofumi Miyashita 《Journal of Modern Physics》 2024年第5期674-689,共16页
Previously, we presented several empirical equations using the cosmic microwave background (CMB) temperature. Next, we propose an empirical equation for the fine-structure constant. Considering the compatibility among... Previously, we presented several empirical equations using the cosmic microwave background (CMB) temperature. Next, we propose an empirical equation for the fine-structure constant. Considering the compatibility among these empirical equations, the CMB temperature (T<sub>c</sub>) and gravitational constant (G) were calculated to be 2.726312 K and 6.673778 × 10<sup>−11</sup> m<sup>3</sup>∙kg<sup>−1</sup>∙s<sup>−2</sup>, respectively. Every equation could be explained in terms of the Compton length of an electron (λ<sub>e</sub>), the Compton length of a proton (λ<sub>p</sub>) and a. Furthermore, every equation could also be explained in terms of Avogadro’s number and the number of electrons in 1 C. However, the ratio of the gravitational force to the electric force cannot be uniquely determined when the unit of the Planck constant (Js) is changed. In this study, we showed that every equation can be described in terms of Planck constant. From the assumption of minimum mass, the ratio of gravitational force to electric force could be elucidated. 展开更多
关键词 Ratio of Gravitational Force to Electric Force Minimum Mass Temperature of the cosmic Microwave Background
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Correspondence Principle for Empirical Equations in Terms of the Cosmic Microwave Background Temperature with Solid-State Ionics
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作者 Tomofumi Miyashita 《Journal of Modern Physics》 2024年第1期51-63,共13页
Previously, we presented several empirical equations using the cosmic microwave background (CMB) temperature that were mathematically connected. Next, we proposed an empirical equation for the fine-structure constant.... Previously, we presented several empirical equations using the cosmic microwave background (CMB) temperature that were mathematically connected. Next, we proposed an empirical equation for the fine-structure constant. Considering the compatibility among these empirical equations, the CMB temperature (T<sub>c</sub>) and gravitational constant (G) were calculated to be 2.726312 K and 6.673778 × 10<sup>-11</sup> m<sup>3</sup>·kg<sup>-1</sup>·s<sup>-2</sup>, respectively. Every equation can be explained in terms of the Compton length of an electron (λ<sub>e</sub>), the Compton length of a proton (λ<sub>p</sub>) and α. However, these equations are difficult to follow. Using the correspondence principle with the thermodynamic principles in solid-state ionics, we propose a canonical ensemble to explain these equations in this report. For this purpose, we show that every equation can be explained in terms of Avogadro’s number and the number of electrons in 1 C. 展开更多
关键词 Temperature of the cosmic Microwave Background
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基于不同背景场的云内COSMIC掩星资料的偏差分析
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作者 殷延安 杨胜朋 《高原气象》 CSCD 北大核心 2023年第5期1351-1360,共10页
利用2007-2009年Cloud Sat卫星云廓线雷达(nadir-pointing cloud profiling radar,CPR)资料,气象、电离层和气候卫星联合观测系统(Global Constellation Observing System for Meteorology,Ionosphere,and Climate,COSMIC)掩星资料,分... 利用2007-2009年Cloud Sat卫星云廓线雷达(nadir-pointing cloud profiling radar,CPR)资料,气象、电离层和气候卫星联合观测系统(Global Constellation Observing System for Meteorology,Ionosphere,and Climate,COSMIC)掩星资料,分析了不同类型云内COSMIC掩星资料与欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)和美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)分析场之间的折射率偏差特征。COSMIC与ECMWF和NCEP之间的折射率偏差分别用Nbias^(ECMWF)和Nbias^(NCEP)表示。研究发现,Nbias^(ECMWF)在积云、层积云、高积云和高层云中的最大值分别为1.2%、0.2%、0.5%和0.2%,而Nbias^(NCEP)则分别为1.8%、0.5%、0.5%和0.4%。在层积云的对流层下层Nbias^(NCEP)存在较大的负值,而Nbias^(ECMWF)为正值。折射率的正偏差随着液态水含量增加而增加。从全球分布来看,赤道辐合带云量丰富,Nbias^(NCEP)和Nbias^(ECMWF)也存在明显的正偏差,它在空间上和水汽的正偏差以及温度的负偏差高度相关。 展开更多
关键词 cosmic掩星 CLOUDSAT 折射率偏差 液态水含量
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Flat Space Cosmology as a Model of Light Speed Cosmic Expansion—Implications for the Vacuum Energy Density
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作者 Eugene Terry Tatum U. V. S. Seshavatharam 《Journal of Modern Physics》 2018年第10期2008-2020,共13页
Cosmologists have long ignored a stipulation by quantum field theorists that the vacuum pressure p corresponding to the zero-state vacuum energy must always be equal in magnitude to the vacuum energy density &rho;... Cosmologists have long ignored a stipulation by quantum field theorists that the vacuum pressure p corresponding to the zero-state vacuum energy must always be equal in magnitude to the vacuum energy density &rho;(i.e., p=&rho;). Although general relativity stipulates the additional condition of proportionality between the vacuum gravitational field and (&rho;+3p), the equation of state for the cosmic vacuum must fulfill both relativistic and quantum stipulations. This paper fully integrates Flat Space Cosmology (FSC) into the Friedmann equations containing a cosmological term, with interesting implications for the nature of dark energy, cosmic entropy and the entropic arrow of time. The FSC vacuum energy density is shown to be equal to the cosmic fluid bulk modulus at all times, thus meeting the quantum theory stipulation of (p=&rho;). To date, FSC is the only viable dark energy cosmological model which has fully-integrated general relativity and quantum features. 展开更多
关键词 cosmology Theory General Relativity Dark Energy cosmic FLATNESS cosmic Entropy Entropic ARROW of Time cosmic Inflation MILNE Universe Black Holes COSMOLOGICAL Constant Problem
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How a Realistic Linear <i>R<sub>h</sub>= ct </i>Model of Cosmology Could Present the Illusion of Late Cosmic Acceleration
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作者 Eugene Terry Tatum U. V. S. Seshavatharam 《Journal of Modern Physics》 2018年第7期1397-1403,共7页
Realistic FLRW cosmic coasting models which contain matter now appear to be a reasonable alternative in explaining the accumulated Supernova Cosmology Project data since 1998. In sharp contrast to the unrealistic orig... Realistic FLRW cosmic coasting models which contain matter now appear to be a reasonable alternative in explaining the accumulated Supernova Cosmology Project data since 1998. In sharp contrast to the unrealistic original classic Milne universe, which was entirely devoid of matter, these modified Milne-type models containing matter, often referred to as realistic linear Rh = ct models, have rapidly become the primary competition with standard cosmology. This paper compares the expected relative luminosity distances and relative angular diameter distances for given magnitudes of redshift within these two competing models. A simple ratio formula is derived, which explains how expected luminosity distances and angular diameter distances for given magnitudes of redshift within a realistic Milne-type cosmic expansion could create the illusion (for standard model proponents) of cosmic acceleration where none exists. 展开更多
关键词 Dark Energy Survey cosmology Theory cosmic COASTING cosmic Flatness Type Ia Supernovae CMBR Flat Space cosmology Milne Universe Theories
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COSMIC与ERA-Interim折射率数据分析海洋边界层时空分布的对比
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作者 袁帅 唐歌实 高鹏 《南京信息工程大学学报(自然科学版)》 CAS 北大核心 2023年第2期244-252,共9页
本文基于小波协方差变换法,使用COSMIC和ERA-Interim两种数据的折射率获取了全球海洋边界层的时空分布情况并进行了对比分析.结果表明:在空间上,由两种数据反演出的海洋边界层高度所显示出的分布特征大致相同,即沿着赤道呈不完全对称分... 本文基于小波协方差变换法,使用COSMIC和ERA-Interim两种数据的折射率获取了全球海洋边界层的时空分布情况并进行了对比分析.结果表明:在空间上,由两种数据反演出的海洋边界层高度所显示出的分布特征大致相同,即沿着赤道呈不完全对称分布,仅在个别海域有所差别;在季节及月变化方面,两者均呈现出夏季较高的特点;在日变化特征上,两者变化均不明显,但ERA-Interim数据的海洋边界层高度的日变化特征与太阳辐射的日变化特征更加符合;在数值差异上,COSMIC数据要比ERA-Interim数据的结果高500~1000 m,且低纬度地区两者差异大于高纬度地区,夏季两者差异小于冬季. 展开更多
关键词 cosmic掩星 ERA-INTERIM 折射率 海洋边界层 小波协方差变换法 时空分布特征
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Cosmic Contributions to the Deposition of Petroleum Source Rocks: Review and Analysis 被引量:1
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作者 Heinz-Jürgen Brink 《International Journal of Geosciences》 2023年第11期1123-1145,共23页
The development of globally distributed Phanerozoic petroleum source rocks is concentrated on time intervals, which correlate convincingly with climatic driven glaciation epochs of Earth’s history, repeated every 150... The development of globally distributed Phanerozoic petroleum source rocks is concentrated on time intervals, which correlate convincingly with climatic driven glaciation epochs of Earth’s history, repeated every 150 million years, and during sea level high stands and maxima of global magmatism with a period of 300 million years. The 150 million year periodicity appears to be related to the path of the solar system through the spiral arms of the Milky Way and the 300 million year periodicity to changes of the spiral system. The spiral arms are preferred birth places of new stars, of which the larger ones have only smaller lifespans. Their preliminary deaths ended with explosions and selectively with the development of so-called white dwarfs, neutron stars or black holes. The times of the explosions of intermediate (sun-like) stars can be determined by measuring the present brightness of the dwarfs. Not surprisingly the last two maxima of recordable near solar system star explosions took place during the presumably spiral arms driven glacial epochs in Eocene to present and Upper Jurassic times. Such near solar system star explosions may have been the source of intense neutrino showers, cosmic rays and star dust. This dust contained all kinds of chemical elements, including phosphorus and uranium. Such cosmic phosphorus may have supported, through fertilizing, the distribution of life on Earth additionally to local phosphorus resources via bloom of biota in lakes and oceans and the enhanced growth of plants on land across all climatic zones. Subsequently it maintained the development of petroleum source rocks of all organic matter types within black shales and coals. Via the distribution of remnants of exploding stars—mainly white dwarfs, but neutron stars and black holes have to be counted as well—a cosmic contribution can therefore casually linked to the deposition of petroleum source rocks on Earth, not only purely correlatively by their contemporaneous appearances. 展开更多
关键词 cosmic Rays cosmic Dust Milky Way Spiral Arms STARS Phosphorus URANIUM Petroleum Source Rock
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Revisiting the Epoch of Cosmic Acceleration
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作者 David Dahiya Deepak Jain 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第9期1-11,共11页
We revisit the epoch of cosmic speed-up characterized by the redshift of transition from a decelerated to an accelerated phase.This redshift is termed the transition redshift(z_(t)).We use the spatially flat and non-f... We revisit the epoch of cosmic speed-up characterized by the redshift of transition from a decelerated to an accelerated phase.This redshift is termed the transition redshift(z_(t)).We use the spatially flat and non-flat variants of the most commonΛCDM and XCDM models to put constraints on the transition redshift along with the other model parameters.The data for this analysis come from the recent and updated Pantheon+supernova(SN)data set and the Hubble parameter measurements obtained from Cosmic Chronometers.We consider both data sets with their respective covariance matrices incorporating all statistical and systematic uncertainties.We observe that using the combined data sets of H(z)and SNe,the best fit value of transition redshift lies in the range 0.61<z_(t)<0.79 for all four dark energy models.Incidentally,we observe a positive curvature for the non-flat models,correlations between several model parameters and a strong degeneracy between the curvature and the equation of state parameter. 展开更多
关键词 (cosmology )dark energy-(cosmology )cosmological parameters-cosmology OBSERVATIONS
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Cosmology of a Chaplygin Gas Model Under f(T)Gravity and Evolution of Primordial Perturbations
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作者 Sanjeeda Sultana Surajit Chattopadhyay 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第6期187-198,共12页
This paper reports a detailed study of generalized Chaplygin gas(GCG)with power law form of scale factor and truncated form of the scale factor using binomial expansion in both interacting and non-interacting scenario... This paper reports a detailed study of generalized Chaplygin gas(GCG)with power law form of scale factor and truncated form of the scale factor using binomial expansion in both interacting and non-interacting scenarios along with its cosmological consequences,studied in terms of equation of state(EoS)parameter.In the non-interacting scenario,the EoS parameter behaves as quintessence in both forms of the scale factor.In the interacting scenario,the EoS parameter behaves as phantom and for the truncated form of the scale factor,it violates the constraints of the positive parameterα.The cosmological implementation of GCG interacting with pressureless dark matter is investigated in the framework of f(T)modified gravity,where T is the torsion scalar in teleparallelism.The interaction term is directly proportional to the GCG density with positive coupling constant.In f(T)gravity,the EoS is behaving like phantom.The stability of the reconstructed model is investigated and it is found to be stable against small gravitational perturbations,i.e.,the squared speed of sound is non-negative and an increasing function of cosmic time t.We have observed that our reconstructed f(T)model satisfies one of the sufficient conditions of a realistic reconstructed model and it is consistent with the CMB constraints and primordial nucleosynthesis.Cosmology of primordial perturbations has also been analyzed and the self-interacting potential has been found to be an increasing function of cosmic time t. 展开更多
关键词 (cosmology:)dark energy cosmology:theory (cosmology:)cosmological parameters
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A Better Candidate for Dark Matter is Cosmic Plasma
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作者 Yi-Jia Zheng 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第10期277-280,共4页
In the ΛCDM cosmological model, based on observations of supernovae Ia, the cosmic dark energy density is assumed to be Ω_(Λ)~ 0.70 and the gravitational mass density is assumed to be Ω_(m)~ 0.30. Based on the ass... In the ΛCDM cosmological model, based on observations of supernovae Ia, the cosmic dark energy density is assumed to be Ω_(Λ)~ 0.70 and the gravitational mass density is assumed to be Ω_(m)~ 0.30. Based on the assumption that the observed cosmic microwave background(CMB) is a thermal relic of the early hot universe, the cosmic plasma density should be small, i.e., Ω_(b)~ 0.05(otherwise the Sunyaev-Zeldovich effect of the cosmic plasma would ruin the observed CMB's perfect blackbody spectrum). To fill the gap between Ω_(m) and Ω_(b), non-baryonic dark matter Ω_(c)~ 0.25 is introduced into the ΛCDM model. If the CMB is the result of a partial thermal equilibrium between cosmic radiation and cosmic plasma, then the observed perfect blackbody spectrum of the CMB can coexist with cosmic plasma. In this case, it is not necessary to introduce non-baryonic cold dark matter into cosmological models. A better candidate for dark matter is the cosmic plasma. 展开更多
关键词 cosmology:theory (cosmology:)dark matter gravitational lensing:weak X-rays:galaxies:clusters
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