Pub Date : 2024-05-11DOI: 10.1142/s0218271824500196
M. Ilyas, A. R. Athar, Fawad Khan, Nasreen Ghafoor, Haifa I. Alrebdi, Kottakkaran Sooppy Nisar, Abdel-Haleem Abdel-Aty
This research work provides an exhaustive investigation of the viability of different coupled wormhole (WH) geometries with the relativistic matter configurations in the extended gravity framework. We consider a specific model in the context of -gravity for this purpose. Also, we assume a static spherically symmetric spacetime geometry and a unique distribution of matter with a set of shape functions () for analyzing different energy conditions. In addition to this, we examined WH-models in the equilibrium scenario by employing anisotropic fluid. The corresponding results are obtained using numerical methods and then presented using different plots. In this case, gravity generates additional curvature quantities, which can be thought of as gravitational objects that maintain irregular WH-situations. Based on our findings, we conclude that in the absence of exotic matter, WH can exist in some specific regions of the parametric space using modified gravity model as .
{"title":"Some specific wormhole solutions in extended f(R,G,T) gravity","authors":"M. Ilyas, A. R. Athar, Fawad Khan, Nasreen Ghafoor, Haifa I. Alrebdi, Kottakkaran Sooppy Nisar, Abdel-Haleem Abdel-Aty","doi":"10.1142/s0218271824500196","DOIUrl":"https://doi.org/10.1142/s0218271824500196","url":null,"abstract":"<p>This research work provides an exhaustive investigation of the viability of different coupled wormhole (WH) geometries with the relativistic matter configurations in the <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>,</mo><mi>T</mi><mo stretchy=\"false\">)</mo></math></span><span></span> extended gravity framework. We consider a specific model in the context of <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>,</mo><mi>T</mi><mo stretchy=\"false\">)</mo></math></span><span></span>-gravity for this purpose. Also, we assume a static spherically symmetric spacetime geometry and a unique distribution of matter with a set of shape functions (<span><math altimg=\"eq-00005.gif\" display=\"inline\" overflow=\"scroll\"><mi>β</mi><mo stretchy=\"false\">(</mo><mi>r</mi><mo stretchy=\"false\">)</mo></math></span><span></span>) for analyzing different energy conditions. In addition to this, we examined WH-models in the equilibrium scenario by employing anisotropic fluid. The corresponding results are obtained using numerical methods and then presented using different plots. In this case, <span><math altimg=\"eq-00006.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>,</mo><mi>T</mi><mo stretchy=\"false\">)</mo></math></span><span></span> gravity generates additional curvature quantities, which can be thought of as gravitational objects that maintain irregular WH-situations. Based on our findings, we conclude that in the absence of exotic matter, WH can exist in some specific regions of the parametric space using modified gravity model as <span><math altimg=\"eq-00007.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>,</mo><mi>T</mi><mo stretchy=\"false\">)</mo><mo>=</mo><mi>R</mi><mo>+</mo><mi>α</mi><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mi>β</mi><msup><mrow><mi>G</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>+</mo><mi>γ</mi><mi>G</mi><mo>ln</mo><mo stretchy=\"false\">(</mo><mi>G</mi><mo stretchy=\"false\">)</mo><mo>+</mo><mi>λ</mi><mi>T</mi></math></span><span></span>.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"20 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141151445","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}
Pub Date : 2024-04-30DOI: 10.1142/s0218271824500111
M. Hoyuelos, P. Sisterna
Dark energy is an elusive concept, which has been introduced two decades ago in order to make the acceleration of the universe a comprehensible phenomenon. However, the nature of this energy is far from being understood, both from a fundamental as well as an observational way. In this work, we study cosmological consequences of the existence of particles (which we called “ewkons” in a previous work) which are quasi distinguishable, obey unorthodox statistics, and have an equation of state similar to many existent dark energy candidates (including negative relation between pressure and energy density). We find an effective scalar field description of this ewkon fluid, and obtain cosmological solutions for the dark energy-dominated epoch. This can be considered as a one-parameter class of dark energy models.
{"title":"Dark energy based on exotic statistics","authors":"M. Hoyuelos, P. Sisterna","doi":"10.1142/s0218271824500111","DOIUrl":"https://doi.org/10.1142/s0218271824500111","url":null,"abstract":"<p>Dark energy is an elusive concept, which has been introduced two decades ago in order to make the acceleration of the universe a comprehensible phenomenon. However, the nature of this energy is far from being understood, both from a fundamental as well as an observational way. In this work, we study cosmological consequences of the existence of particles (which we called “ewkons” in a previous work) which are quasi distinguishable, obey unorthodox statistics, and have an equation of state similar to many existent dark energy candidates (including negative relation between pressure and energy density). We find an effective scalar field description of this ewkon fluid, and obtain cosmological solutions for the dark energy-dominated epoch. This can be considered as a one-parameter class of dark energy models.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140831308","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}
Pub Date : 2024-04-13DOI: 10.1142/s021827182350102x
Angel D. D. Masa, Vilson T. Zanchin
In this paper, we obtain a new class of stationary axisymmetric spacetimes by using the Gürses–Gürsey metric with an appropriate mass function in order to generate a rotating core of matter that may be smoothly matched to the exterior Kerr metric. The same stationary spacetimes may be obtained by applying a slightly modified version of the Newman–Janis algorithm to a nonrotating spherically symmetric seed metric. The starting spherically symmetric configuration represents a nonisotropic de Sitter-type fluid whose radial pressure satisfies an state equation of the form , where the energy density is chosen to be the Tolman-type-VII energy density [R. C. Tolman, Phys. Rev.55, 364 (1939)]. The resulting rotating metric is then smoothly matched to the exterior Kerr metric, and the main properties of the obtained geometries are investigated. All the solutions considered in this study are regular in the sense they are free of curvature singularities. Depending on the relative values of the total mass m and rotation parameter a, the resulting stationary spacetimes represent different kinds of rotating compact objects such as regular black holes, extremal regular black holes, and regular starlike configurations.
在本文中,我们利用具有适当质量函数的 Gürses-Gürsey 度量,生成了一类新的静止轴对称时空,其旋转物质核心可与外部克尔度量平滑匹配。对非旋转球面对称种子度量应用稍加修改的纽曼-简尼斯算法,也可以得到相同的静止时空。起始球对称构型代表一种非各向同性的德西特流体,其径向压力 pr 满足形式为 pr=-ρ 的状态方程,其中能量密度 ρ 被选作托尔曼型-VII 能量密度[R. C. Tolman, Phys. Rev.55, 364 (1939)]。然后将得到的旋转度量与外部克尔度量进行平滑匹配,并研究得到的几何图形的主要性质。本研究中考虑的所有解都是正则解,即不存在曲率奇异性。根据总质量 m 和旋转参数 a 的相对值,得到的静止时空代表了不同类型的旋转紧凑天体,如规则黑洞、极端规则黑洞和规则星状构型。
{"title":"Rotating regular black holes and other compact objects with a Tolman-type potential as a regular interior for the Kerr metric","authors":"Angel D. D. Masa, Vilson T. Zanchin","doi":"10.1142/s021827182350102x","DOIUrl":"https://doi.org/10.1142/s021827182350102x","url":null,"abstract":"<p>In this paper, we obtain a new class of stationary axisymmetric spacetimes by using the Gürses–Gürsey metric with an appropriate mass function in order to generate a rotating core of matter that may be smoothly matched to the exterior Kerr metric. The same stationary spacetimes may be obtained by applying a slightly modified version of the Newman–Janis algorithm to a nonrotating spherically symmetric seed metric. The starting spherically symmetric configuration represents a nonisotropic de Sitter-type fluid whose radial pressure <span><math altimg=\"eq-00002.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>p</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span><span></span> satisfies an state equation of the form <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>p</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>=</mo><mo>−</mo><mi>ρ</mi></math></span><span></span>, where the energy density <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><mi>ρ</mi></math></span><span></span> is chosen to be the Tolman-type-VII energy density [R. C. Tolman, <i>Phys. Rev.</i><b>55</b>, 364 (1939)]. The resulting rotating metric is then smoothly matched to the exterior Kerr metric, and the main properties of the obtained geometries are investigated. All the solutions considered in this study are regular in the sense they are free of curvature singularities. Depending on the relative values of the total mass <i>m</i> and rotation parameter <i>a</i>, the resulting stationary spacetimes represent different kinds of rotating compact objects such as regular black holes, extremal regular black holes, and regular starlike configurations.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"82 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140573477","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}
In this paper, we reproduce the rotation curve of the Andromeda galaxy (M31) by taking into account its bulge, disk and halo components, considering the last one to contain the major part of dark matter mass. Hence, our prescription is to split the galactic bulge into two components, namely, the inner and main bulges, respectively. Both bulges are thus modeled by exponential density profiles since we underline that the widely accepted de Vaucouleurs law fails to reproduce the whole galactic bulge rotation curve. In addition, we adopt various well-known phenomenological dark matter profiles to estimate the dark matter mass in the halo region. Moreover, we apply the least-squares fitting method to determine from the rotation curve the model free parameters, namely, the characteristic (central) density, scale radius and consequently the total mass. To do so, we perform Markov chain Monte Carlo statistical analyses based on the Metropolis algorithm, maximizing our likelihoods adopting velocity and radii data points of the rotation curves. We do not fit separately the components for bulges, disk and halo, but we perform an overall fit including all the components and employing all the data points. Thus, we critically analyze our corresponding findings and, in particular, we employ the Bayesian information criterion to assess the most accredited model to describe M31 dark matter dynamics.
{"title":"Numerical analyses of M31 dark matter profiles","authors":"Kuantay Boshkayev, Talgar Konysbayev, Yergali Kurmanov, Orlando Luongo, Marco Muccino, Hernando Quevedo, Gulnur Zhumakhanova","doi":"10.1142/s0218271824500160","DOIUrl":"https://doi.org/10.1142/s0218271824500160","url":null,"abstract":"<p>In this paper, we reproduce the rotation curve of the Andromeda galaxy (M31) by taking into account its bulge, disk and halo components, considering the last one to contain the major part of dark matter mass. Hence, our prescription is to split the galactic bulge into two components, namely, the inner and main bulges, respectively. Both bulges are thus modeled by exponential density profiles since we underline that the widely accepted de Vaucouleurs law fails to reproduce the whole galactic bulge rotation curve. In addition, we adopt various well-known phenomenological dark matter profiles to estimate the dark matter mass in the halo region. Moreover, we apply the least-squares fitting method to determine from the rotation curve the model free parameters, namely, the characteristic (central) density, scale radius and consequently the total mass. To do so, we perform Markov chain Monte Carlo statistical analyses based on the Metropolis algorithm, maximizing our likelihoods adopting velocity and radii data points of the rotation curves. We do not fit separately the components for bulges, disk and halo, but we perform an overall fit including all the components and employing all the data points. Thus, we critically analyze our corresponding findings and, in particular, we employ the Bayesian information criterion to assess the most accredited model to describe M31 dark matter dynamics.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"4 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140573741","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}
Pub Date : 2024-03-26DOI: 10.1142/s0218271824500123
Didam G. A. Duniya
The imprint of interacting dark energy (IDE) needs to be correctly identified in order to avoid bias in constraints on IDE. This paper investigates the large-scale imprint of IDE in redshift-space distortions (RSDs), using Euclid-like photometric prescriptions. A first attempt at incorporating the IDE dynamics in the galaxy (clustering and evolution) biases is made. Without IDE dynamics taken into account in the galaxy biases, as is conventionally done, the results suggest that for a constant dark energy (DE) equation of state parameter, an IDE model where the DE transfer rate is proportional to the DE density exhibits an alternating, positive–negative effect in the RSDs angular power spectrum. However, when the IDE dynamics is incorporated in the galaxy biases, it is found that the apparent positive–negative alternating effect vanishes: implying that neglecting IDE dynamics in the galaxy biases can result in “artifacts” that can lead to incorrect identification of the IDE imprint. In general, the results show that multi-tracer analysis will be needed to beat down cosmic variance in order for the RSDs angular power spectrum as a statistic to be a viable diagnostic of IDE. Moreover, it is found that RSDs hold the potential to constrain IDE on large scales, at redshifts , with the scenario having IDE dynamics incorporated in the biases showing better potential.
需要正确识别相互作用暗能量(IDE)的印记,以避免对 IDE 的约束产生偏差。本文利用类似欧几里得的测光规定,研究了IDE在红移空间扭曲(RSDs)中的大尺度印记。首次尝试将 IDE 动态纳入星系(聚类和演化)偏差。结果表明,在暗能量(DE)状态方程参数不变的情况下,暗能量转移速率与暗能量密度成正比的IDE模型在RSD角功率谱中表现出正负交替的效应。然而,当把 IDE 动力学纳入星系偏差时,发现明显的正负交替效应消失了:这意味着在星系偏差中忽略 IDE 动力学会导致 "伪影",从而导致 IDE 印记的错误识别。总之,研究结果表明,需要进行多追踪器分析来消除宇宙差异,才能使 RSDs 角功率谱作为一种统计量成为 IDE 的可行诊断方法。此外,研究还发现 RSDs 有可能在大尺度上对 z≤1 的红移进行 IDE 约束,而将 IDE 动力学纳入偏差的方案则显示出更好的潜力。
{"title":"Qualitative probe of interacting dark energy with redshift-space distortions","authors":"Didam G. A. Duniya","doi":"10.1142/s0218271824500123","DOIUrl":"https://doi.org/10.1142/s0218271824500123","url":null,"abstract":"<p>The imprint of interacting dark energy (IDE) needs to be correctly identified in order to avoid bias in constraints on IDE. This paper investigates the large-scale imprint of IDE in redshift-space distortions (RSDs), using <i>Euclid</i>-like photometric prescriptions. A first attempt at incorporating the IDE dynamics in the galaxy (clustering and evolution) biases is made. Without IDE dynamics taken into account in the galaxy biases, as is conventionally done, the results suggest that for a constant dark energy (DE) equation of state parameter, an IDE model where the DE transfer rate is proportional to the DE density exhibits an alternating, positive–negative effect in the RSDs angular power spectrum. However, when the IDE dynamics is incorporated in the galaxy biases, it is found that the apparent positive–negative alternating effect vanishes: implying that neglecting IDE dynamics in the galaxy biases can result in “artifacts” that can lead to incorrect identification of the IDE imprint. In general, the results show that multi-tracer analysis will be needed to beat down cosmic variance in order for the RSDs angular power spectrum as a statistic to be a viable diagnostic of IDE. Moreover, it is found that RSDs hold the potential to constrain IDE on large scales, at redshifts <span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><mi>z</mi><mo>≤</mo><mn>1</mn></math></span><span></span>, with the scenario having IDE dynamics incorporated in the biases showing better potential.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"27 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315407","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}
Pub Date : 2024-03-23DOI: 10.1142/s0218271824500093
Peter A. Hogan, Dirk Puetzfeld
Colliding or noncolliding plane-fronted electromagnetic or gravitational waves are the asymptotic limit of Robinson–Trautman spherical electromagnetic or gravitational waves. Noncolliding plane-fronted waves contain no information about their sources whereas colliding waves contain information about possibly the motion of their sources. As a first step to investigate the latter phenomenon, we construct an asymptotic limit of Liénard–Wiechert electromagnetic fields in the context of Minkowskian spacetime. This has the advantage that the source is well known and the calculations can be carried out in full detail. The final result is an algebraically general Maxwell field which consists of colliding plane-fronted waves in a subregion of Minkowskian spacetime and an interesting byproduct is a novel perspective on a Maxwell field originally discovered by Bateman.
{"title":"Plane-fronted electromagnetic waves and an asymptotic limit of Liénard–Wiechert fields","authors":"Peter A. Hogan, Dirk Puetzfeld","doi":"10.1142/s0218271824500093","DOIUrl":"https://doi.org/10.1142/s0218271824500093","url":null,"abstract":"<p>Colliding or noncolliding plane-fronted electromagnetic or gravitational waves are the asymptotic limit of Robinson–Trautman spherical electromagnetic or gravitational waves. Noncolliding plane-fronted waves contain no information about their sources whereas colliding waves contain information about possibly the motion of their sources. As a first step to investigate the latter phenomenon, we construct an asymptotic limit of Liénard–Wiechert electromagnetic fields in the context of Minkowskian spacetime. This has the advantage that the source is well known and the calculations can be carried out in full detail. The final result is an algebraically general Maxwell field which consists of colliding plane-fronted waves in a subregion of Minkowskian spacetime and an interesting byproduct is a novel perspective on a Maxwell field originally discovered by Bateman.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"67 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140201919","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}
Pub Date : 2024-03-22DOI: 10.1142/s0218271824500068
Manjeet Kaur, Debottam Nandi, Debajyoti Choudhury, T. R. Seshadri
Cosmological models with inflation and those with bounce have their own strengths and weaknesses. Here, we construct a model in which a phase of bounce is followed by a viable inflationary phase. This incorporates several advantages of both and hence, is a more viable model for cosmic evolution. We explore scenarios wherein the bouncing phase smoothly transits to an inflationary one, with the pivot scale leaving the Hubble horizon during the latter era, thereby maintaining consistency with observations. Staying within the ambit of Einstein–Hilbert gravity augmented by the inflation, we ensure a pre-inflationary bounce by introducing a second scalar field that helps engineer the requisite violation of the null energy condition. Potential ghost instabilities can be mitigated by invoking a nontrivial coupling between the two scalar fields.
{"title":"Universe bouncing its way to inflation","authors":"Manjeet Kaur, Debottam Nandi, Debajyoti Choudhury, T. R. Seshadri","doi":"10.1142/s0218271824500068","DOIUrl":"https://doi.org/10.1142/s0218271824500068","url":null,"abstract":"<p>Cosmological models with inflation and those with bounce have their own strengths and weaknesses. Here, we construct a model in which a phase of bounce is followed by a viable inflationary phase. This incorporates several advantages of both and hence, is a more viable model for cosmic evolution. We explore scenarios wherein the bouncing phase smoothly transits to an inflationary one, with the pivot scale leaving the Hubble horizon during the latter era, thereby maintaining consistency with observations. Staying within the ambit of Einstein–Hilbert gravity augmented by the inflation, we ensure a pre-inflationary bounce by introducing a second scalar field that helps engineer the requisite violation of the null energy condition. Potential ghost instabilities can be mitigated by invoking a nontrivial coupling between the two scalar fields.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"157 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140201868","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}
Pub Date : 2024-03-20DOI: 10.1142/s0218271824500081
Anirudh Pradhan, Safiqul Islam, M. Zeyauddin, Ayan Banerjee
In this paper, we explore the physical properties and characteristics of static, spherically symmetric wormholes in the background of Rastall–Rainbow gravity. The Rastall–Rainbow gravity theory has recently been proposed as a combination of two theories, namely, the Rastall theory and the Rainbow description. We implemented noncommutativity by adopting two different distributions of energy density (Gaussian and Lorentzian) in the Morris and Thorne metric. We solve the field equations analytically and discuss all the properties of wormholes depending on the two model parameters. Notably, for specific parameter ranges, one can alleviate the violation of the WEC at the throat and its neighborhood.
{"title":"Noncommutative effects on wormholes in Rastall–Rainbow gravity","authors":"Anirudh Pradhan, Safiqul Islam, M. Zeyauddin, Ayan Banerjee","doi":"10.1142/s0218271824500081","DOIUrl":"https://doi.org/10.1142/s0218271824500081","url":null,"abstract":"<p>In this paper, we explore the physical properties and characteristics of static, spherically symmetric wormholes in the background of Rastall–Rainbow gravity. The Rastall–Rainbow gravity theory has recently been proposed as a combination of two theories, namely, the Rastall theory and the Rainbow description. We implemented noncommutativity by adopting two different distributions of energy density (Gaussian and Lorentzian) in the Morris and Thorne metric. We solve the field equations analytically and discuss all the properties of wormholes depending on the two model parameters. Notably, for specific parameter ranges, one can alleviate the violation of the WEC at the throat and its neighborhood.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140167258","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}
Pub Date : 2024-03-15DOI: 10.1142/s0218271824500056
Bivash Majumder, Saibal Ray, Goutam Manna
Based on the work of Chandrasekhar [The Mathematical Theory of Black Holes, Chap. 3, Sec. 20 (Oxford University Press, 1992)], we investigate the null geodesic structure of the emergent Barriola–Vilenkin (BV) spacetime in the context of k-essence theory. For k-essence, the emergent gravity metric is a one-to-one correspondence with the BV metric connected to the Schwarzschild background, where the global monopole charge is replaced by the dark energy density. This equivalence holds specifically for a certain class of k-essence scalar fields that have been constructed by Gangopadhyay and Manna [Eur. Phys. Lett.100, 49001 (2012)]. We have traced out different trajectories for null geodesic in the presence of dark energy for the k-essence emergent BV spacetime. It is demonstrated that the outcomes deviate from the typical Schwarzschild spacetime owing to the fundamental configuration with a constant dark energy density.
{"title":"Null geodesic structure for the Barriola–Vilenkin spacetime via k-essence","authors":"Bivash Majumder, Saibal Ray, Goutam Manna","doi":"10.1142/s0218271824500056","DOIUrl":"https://doi.org/10.1142/s0218271824500056","url":null,"abstract":"<p>Based on the work of Chandrasekhar [<i>The Mathematical Theory of Black Holes</i>, Chap. 3, Sec. 20 (Oxford University Press, 1992)], we investigate the null geodesic structure of the emergent Barriola–Vilenkin (BV) spacetime in the context of <i>k</i>-essence theory. For <i>k</i>-essence, the emergent gravity metric is a one-to-one correspondence with the BV metric connected to the Schwarzschild background, where the global monopole charge is replaced by the dark energy density. This equivalence holds specifically for a certain class of <i>k</i>-essence scalar fields that have been constructed by Gangopadhyay and Manna [<i>Eur. Phys. Lett.</i> <b>100</b>, 49001 (2012)]. We have traced out different trajectories for null geodesic in the presence of dark energy for the <i>k</i>-essence emergent BV spacetime. It is demonstrated that the outcomes deviate from the typical Schwarzschild spacetime owing to the fundamental configuration with a constant dark energy density.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"20 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140153423","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}
Pub Date : 2024-02-21DOI: 10.1142/s0218271823501110
Gianluca Calcagni, Marco Frasca, Anish Ghoshal
We consider a formalism to describe the false-vacuum decay of a scalar field in gauge theories in non-perturbative regimes. We find that the larger the gauge coupling with respect to the self-coupling of the scalar, the shallower the local minimum of the unstable vacuum, to the point where it disappears. This offers the possibility to obtain a consistent picture of early universe cosmology: at high temperatures, a false-vacuum decay is strongly favored and the universe naturally evolves towards a stable state.
{"title":"Effective potential in non-perturbative gauge theories","authors":"Gianluca Calcagni, Marco Frasca, Anish Ghoshal","doi":"10.1142/s0218271823501110","DOIUrl":"https://doi.org/10.1142/s0218271823501110","url":null,"abstract":"<p>We consider a formalism to describe the false-vacuum decay of a scalar field in gauge theories in non-perturbative regimes. We find that the larger the gauge coupling with respect to the self-coupling of the scalar, the shallower the local minimum of the unstable vacuum, to the point where it disappears. This offers the possibility to obtain a consistent picture of early universe cosmology: at high temperatures, a false-vacuum decay is strongly favored and the universe naturally evolves towards a stable state.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"9 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125556","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}