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Baryon Asymmetry Constraints on Extended Symmetric Teleparallel Gravity 扩展对称远平行引力的重子不对称约束
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700026
S. A. Narawade, S. K. Tripathy, Raghunath Patra, B. Mishra
{"title":"Baryon Asymmetry Constraints on Extended Symmetric Teleparallel Gravity","authors":"S. A. Narawade,&nbsp;S. K. Tripathy,&nbsp;Raghunath Patra,&nbsp;B. Mishra","doi":"10.1134/S0202289324700026","DOIUrl":"10.1134/S0202289324700026","url":null,"abstract":"<p>We have explored the observed matter-antimatter asymmetry in the Universe to constrain the model parameters in Extended Symmetric Teleparallel Gravity (STG) or <span>(f(Q,T))</span> gravity, where <span>(Q)</span> is the nonmetricity and <span>(T)</span> is the trace of the energy momentum tensor. We have considered two functional forms of <span>(f(Q,T))</span> to find the baryon asymmetry to entropy ratio calculated at a decoupling temperature. Two different data sets, namely, the Hubble data set and the <span>(text{Hubble}+text{BAO}+text{Pantheon})</span> data set, are used to constrain the scale factor, and the constrained model is used to obtain the baryon asymmetry to entropy ratio. It is observed that the model constrained from the Hubble data set favors a narrow range of the <span>(f(Q,T))</span> gravity parameters to reproduce the observed baryon asymmetry.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"135 - 140"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141147138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Birkhoff Integrability of Truncated Hořava–Lifshitz Mixmaster Model near the Cosmological Singularity 宇宙奇点附近截断霍热瓦-利夫希茨混合主模型的伯克霍夫积分性
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700087
A. E. Pavlov, S. M. Gaidar
{"title":"Birkhoff Integrability of Truncated Hořava–Lifshitz Mixmaster Model near the Cosmological Singularity","authors":"A. E. Pavlov,&nbsp;S. M. Gaidar","doi":"10.1134/S0202289324700087","DOIUrl":"10.1134/S0202289324700087","url":null,"abstract":"<p>The Hořava–Lifshitz mixmaster cosmological model near the cosmological singularity is presented as a generalized Euclidean Toda chain. Restricting to dominant vectors of the spectrum, we get a truncated model that qualitatively well describes the mixmaster model. The truncated model is associated with an affine Kac–Moody Lie algebra <span>(A_{2}^{+})</span>. According to the Adler–van Moerbeke criterion, the truncated Hamiltonian system is algebraically completely integrable.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"189 - 196"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141114680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Redshift Drift in the Universe: Theoretical Features and Observational Constraints 宇宙中的红移漂移：理论特征与观测约束
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700105
Nishant Singla, Mukesh Kumar Gupta, Mukesh Kumar, Manvinder Singh, Anil Kumar Yadav, G. K. Goswami, Rajendra Prasad
{"title":"Redshift Drift in the Universe: Theoretical Features and Observational Constraints","authors":"Nishant Singla,&nbsp;Mukesh Kumar Gupta,&nbsp;Mukesh Kumar,&nbsp;Manvinder Singh,&nbsp;Anil Kumar Yadav,&nbsp;G. K. Goswami,&nbsp;Rajendra Prasad","doi":"10.1134/S0202289324700105","DOIUrl":"10.1134/S0202289324700105","url":null,"abstract":"<p>We investigate an exact Universe model which is observationally viable and filled with a binary mixture of a perfect fluid and the cosmological constant <span>(Lambda)</span>. We consider the redshift drift <span>(dot{z}=(1+z)H_{0}-H(z))</span> and perform statistical tests to obtain the best fit value of the model parameters of the derived Universe with its observed values. Here, <span>(H_{0})</span> and <span>(z)</span> denote the present value of the Hubble constant and the redshift, respectively. We estimate the best fit values of the Hubble constant and the density parameters as <span>(H_{0}=68.58pm 0.84)</span> km/(s Mpc), <span>((Omega_{m})_{0}=0.26pm 0.010)</span>, and <span>((Omega_{Lambda})_{0}=0.71pm 0.025)</span> by bounding the derived model with the latest observational Hubble data (OHD), while with joint Pantheon data and OHD, its values are <span>(H_{0}=71.93pm 0.58)</span> km/(s Mpc), <span>((Omega_{m})_{0}=0.272pm 0.06)</span>, and <span>((Omega_{Lambda})_{0}=0.74pm 0.09)</span>. The analysis of the deceleration and jerk parameters shows that the Universe in the derived model is compatible with the <span>(Lambda)</span>CDM model. We also investigate that the cosmological models owning a redshift drift minimize the <span>(H_{0})</span> tension.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"211 - 221"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Formation of Supermassive Nuclei of Black Holes in the Early Universe by the Mechanism of Scalar-Gravitational Instability. III. Large-Scale Picture 早期宇宙中黑洞超大质量核的形成：标量-引力不稳定性机制。III.大尺度图景
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700038
Yu. G. Ignat’ev
{"title":"Formation of Supermassive Nuclei of Black Holes in the Early Universe by the Mechanism of Scalar-Gravitational Instability. III. Large-Scale Picture","authors":"Yu. G. Ignat’ev","doi":"10.1134/S0202289324700038","DOIUrl":"10.1134/S0202289324700038","url":null,"abstract":"<p>We study the dependence of the parameters of the evolution of scalarly charged black holes (BHs) in the early Universe on the parameters of field theories of interaction, and the influence of the geometric structure of the relative position of BHs on the limitation of their maximum mass, The problem of the metric of a scalarly charged BH in a medium of expanding scalarly charged matter is discussed, the expression is obtained for the macroscopic cosmological constant at late stages of expansion, generated by quadratic fluctuations of the metric, connecting the cosmological constant value with the BH masses and their concentration.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"141 - 148"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141147170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Circularly Polarized Light in Kerr Gravitational Field: Its Implication in Spin-Gravity Interaction 克尔引力场中的圆偏振光：其在自旋引力相互作用中的意义
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700099
A. K. Sen
{"title":"Circularly Polarized Light in Kerr Gravitational Field: Its Implication in Spin-Gravity Interaction","authors":"A. K. Sen","doi":"10.1134/S0202289324700099","DOIUrl":"10.1134/S0202289324700099","url":null,"abstract":"<p>Various calculations carried out in the past to understand the propagation of light in a rotating gravitational field (viz., Kerr field) are examined. For a plane-polarized light, it is observed that due to the effect of rotational gravitational field, the polarization vector of light gets rotated, with the amount of rotation independent from the frequency of the light. In the present work, using the formulations of geometrical optics, I try to find the implications of such findings, which seem to be very strange and give rise to violation of <i>Lorentz Invariance</i> and the <i>Equivalence Principle</i>, which are mostly not accepted by present-day physics. The analysis involves splitting plane-polarized light into left and right circularly polarized components, and then one finds that these two components (with a given frequency) travel with two different velocities in the Kerr field. Also, for an individual circularly polarized component, the velocity of propagation depends on the frequency of light. Assuming the two opposite directions of circularly polarized light to represent two opposite photon spin states, the line element for circularly polarized light is found to depend on the photon spin in addition to frequency. Additional calculations are made to estimate the propagation time delay between two circularly polarized components (with given frequency) between the source and observer at finite distances from the Kerr mass. Some typical estimates of this time delay are made for the Sun and one pulsar, so that in the future one can experimentally verify these results. For an individual circularly polarized component, time delay expressions are also derived for the propagation of light at two different frequencies. It has been found that circularly polarized light with higher frequency (energy) travels faster in a rotating gravitational field as compared to its lower frequency counterpart.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"197 - 210"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Preliminary Study on Earth and Other Planets Shape Determination: Comparison of Classical and Relativistic Gravitational Effects 地球和其他行星形状测定的初步研究：经典引力效应与相对论引力效应的比较
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700075
Sabrina Y. Fazzito, Claudio M. Simeone
{"title":"A Preliminary Study on Earth and Other Planets Shape Determination: Comparison of Classical and Relativistic Gravitational Effects","authors":"Sabrina Y. Fazzito,&nbsp;Claudio M. Simeone","doi":"10.1134/S0202289324700075","DOIUrl":"10.1134/S0202289324700075","url":null,"abstract":"<p>A first introduction is presented to the comparison between classical and relativistic gravitational effects related to planetary shape characterization. The Earth and the giant planets are the examples considered. The analysis is mainly devoted to relativistic and classical predictions of periastron shifts for equatorial or almost equatorial orbits around the Earth and the giant planets, which can be used as tools for determinations of the shape and density distribution. The ratios between relativistic (up to the Lense–Thirring order correction) and classical (resulting from the harmonic expansion) effects and their dependence on the orbit parameters are analyzed in order to identify the conditions improving the possibility to resolve mixed effects. In a complementary approach, predictions for freely falling test particles from relativistic corrections and classical harmonic expansions of the Earth and other planets are compared within the same shape characterization framework.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"172 - 188"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141116076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Are Trapped Surfaces Visible? 受困表面是否可见？
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700130
Ali A. Asgari
{"title":"Are Trapped Surfaces Visible?","authors":"Ali A. Asgari","doi":"10.1134/S0202289324700130","DOIUrl":"10.1134/S0202289324700130","url":null,"abstract":"<p>In 1965, Penrose introduced the idea of a trapped surface which became an essential concept in proving the first singularity theorem. In this work, some neglected aspects of trapped surfaces are considered. Specifically, I discuss that the existence of such a surface in space-time may result in an undesirable consequence: either space-time is singular, or chronology violation arises. Although a trapping region often implies a singularity in space-time, but a singular space-time may not contain any trapped region. Finally, I show that noncosmological trapped surfaces are observer-dependent. It means that some observers in a trapped region may not observe trapped surfaces!</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"235 - 240"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Note on Analogue Semi-Classical Gravity in ((boldsymbol{1+1})) Dimensions 关于（$$boldsymbol{1+1}$$）维度中模拟半经典引力的说明
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700129
Akshat Pandey
{"title":"A Note on Analogue Semi-Classical Gravity in ((boldsymbol{1+1})) Dimensions","authors":"Akshat Pandey","doi":"10.1134/S0202289324700129","DOIUrl":"10.1134/S0202289324700129","url":null,"abstract":"<p>Acoustic space-times have been known to offer analogue models for black hole physics and cosmology. Within this context, aspects of analogue quantum field theories in curved space-time are studied. In particular, some new comments have been made on the analogue Hawking temperature including a quick derivation of the result. Further, analogue cosmology is explored, within which an acoustic version of the Parker–Toms model is proposed, and the corresponding quantities are calculated. The limits of the acoustic analogue are emphasized.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"229 - 234"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141115446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Scalar Fields for Bianchi-I Model in (boldsymbol{f(R,T)}) Theory of Gravity $$boldsymbol{f(R,T)}$$ 引力理论中比安奇-I 模型的标量场
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700117
Yasemin Kabaoğlu, Can Aktaş
{"title":"Scalar Fields for Bianchi-I Model in (boldsymbol{f(R,T)}) Theory of Gravity","authors":"Yasemin Kabaoğlu,&nbsp;Can Aktaş","doi":"10.1134/S0202289324700117","DOIUrl":"10.1134/S0202289324700117","url":null,"abstract":"<p>In physics and cosmology, scalar fields are considered basic. In this study, we are interested to inspect the conduct of massless scalar field (SF) and massive scalar field (MSF) models in <span>(f(R,T))</span> theory for Bianchi-I universe models. We discuss two cosmological models with respect to late cosmic acceleration, using constant scalar potential and exponential scalar potential models. Also, we study the behavior of a massive scalar field. Finally, we obtain our results in <span>(f(R,T))</span> and general relativity (GR). In addition, we obtained an LRS Bianchi-I metric as a result of the solutions we made and selection of special constants.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"222 - 228"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141116514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Shadows and Photon Rings of Binary Black Holes 双黑洞的阴影和光子环
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2024-05-21 DOI: 10.1134/S0202289324700063
S. V. Chernov
{"title":"Shadows and Photon Rings of Binary Black Holes","authors":"S. V. Chernov","doi":"10.1134/S0202289324700063","DOIUrl":"10.1134/S0202289324700063","url":null,"abstract":"<p>We present the images of binary black holes (BHs) using the Majumdar–Papapetrou multi-BH solution, depending on the parameters of the problem: the BH masses, the distance between them, and the inclination of the observer. The images consist of shadows and photon rings. We find that a photon ring structure appears between the BHs. The trajectories of photons are calculated.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"30 2","pages":"165 - 171"},"PeriodicalIF":1.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141147139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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