Journal of High Energy Astrophysics最新文献

{"title":"Study in the non-canonical domain of power law Plateau inflation","authors":"Yogesh ,&nbsp;Mayukh R. Gangopadhyay","doi":"10.1016/j.jheap.2024.10.002","DOIUrl":"10.1016/j.jheap.2024.10.002","url":null,"abstract":"<div><div>The recent Cosmic Microwave Background (CMB) observations are pointing towards a plateau feature in the flat potential of the inflation field to drive the initial acceleration of the Universe. In this regard, Dimopoulos and Owen introduced a very promising model dubbed as Power Law Plateau inflation (PLP) (<span><span>Dimopoulos and Owen, 2016</span></span>) which has this feature in it. But to make this model consistent with observation in the standard cold inflationary scenario, one needs to introduce an epoch of thermal inflation. In this paper, we have shown realizing this model in the non-canonical domain, could actually make the model consistent with the observation without introducing any late-stage thermal inflation. We also report the constraints from the Cosmic Microwave Background observations on the reheating parameter that one can associate with the model parameter.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 214-219"},"PeriodicalIF":10.2,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433133","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}

{"title":"Search for GeV gamma-ray emission from SPT-CL J2012-5649 with six years of DAMPE data","authors":"Siddhant Manna,&nbsp;Shantanu Desai","doi":"10.1016/j.jheap.2024.10.001","DOIUrl":"10.1016/j.jheap.2024.10.001","url":null,"abstract":"<div><div>We search for gamma-ray emission from the galaxy cluster SPT-CL J2012-5649 in the energy range from 3 GeV to 1 TeV using the DArk Matter Particle Explorer (DAMPE) telescope. For our analysis, we use three different templates: point source, radial disk, and radial Gaussian. We do not detect a signal with significance <span><math><mo>&gt;</mo><mn>3</mn><mi>σ</mi></math></span> for any of these templates at any location within <span><math><msub><mrow><mi>R</mi></mrow><mrow><mn>200</mn></mrow></msub></math></span> of the cluster center. We obtain 95% C.L. upper limit on the energy flux ranging between <span><math><mo>∼</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></math></span> and <span><math><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup><mspace></mspace><mtext>MeV</mtext><mspace></mspace><msup><mrow><mtext>cm</mtext></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mspace></mspace><msup><mrow><mtext>s</mtext></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span> depending on the energy range. These upper limits are consistent with a previously reported non-zero flux detected by Fermi-LAT at 6<em>σ</em> significance. This work represents the first proof of principle search for gamma-ray emission from a single galaxy cluster using DAMPE data.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 210-213"},"PeriodicalIF":10.2,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422642","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}

{"title":"Observational analysis of late-time acceleration in f(Q,Lm) gravity","authors":"Kairat Myrzakulov ,&nbsp;M. Koussour ,&nbsp;O. Donmez ,&nbsp;A. Cilli ,&nbsp;E. Güdekli ,&nbsp;J. Rayimbaev","doi":"10.1016/j.jheap.2024.09.014","DOIUrl":"10.1016/j.jheap.2024.09.014","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In this study, we explored late-time cosmology within an extended class of theories based on &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; gravity. This theory generalizes &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; gravity by incorporating a non-minimal coupling between the non-metricity &lt;em&gt;Q&lt;/em&gt; and the matter Lagrangian &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, analogous to the &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; theory. The coupling between &lt;em&gt;Q&lt;/em&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; leads to the non-conservation of the matter energy-momentum tensor. We first investigated a cosmological model defined by the functional form &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt;, where &lt;em&gt;α&lt;/em&gt;, &lt;em&gt;β&lt;/em&gt;, and &lt;em&gt;n&lt;/em&gt; are constants. The derived Hubble parameter &lt;span&gt;&lt;math&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; indicates that &lt;em&gt;n&lt;/em&gt; significantly influences the scaling of &lt;span&gt;&lt;math&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; over cosmic history, with &lt;span&gt;&lt;math&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt; suggesting accelerated expansion. We also examined the simplified case of &lt;span&gt;&lt;math&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;, leading to the linear form &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, consistent with a universe dominated by non-relativistic matter. Using various observational datasets, including &lt;span&gt;&lt;math&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; and Pantheon, we constrained the model parameters. Our analysis showed that the &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; model aligns well with observational results and exhibits similar behavior to the ΛCDM model. The results, with &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.22&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.01&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt; across all datasets, indicate an accelerating universe, highlighting the model's potential as","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 164-171"},"PeriodicalIF":10.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422643","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}

{"title":"Analysis of the drift of the South Atlantic Anomaly using particle monitors onboard Insight-HXMT","authors":"Hai-Sheng Zhao ,&nbsp;Shi-Jie Zheng ,&nbsp;Liu-Yuan Li ,&nbsp;Ming-Yu Ge ,&nbsp;Shuang-Nan Zhang ,&nbsp;Shu Zhang ,&nbsp;Shao-Lin Xiong ,&nbsp;Li-Ming Song","doi":"10.1016/j.jheap.2024.09.013","DOIUrl":"10.1016/j.jheap.2024.09.013","url":null,"abstract":"<div><div>Using the particle monitors aboard <span><math><mi>I</mi><mi>n</mi><mi>s</mi><mi>i</mi><mi>g</mi><mi>h</mi><mi>t</mi></math></span>-HXMT satellite, we analyzed over 6.5 years of continuous data to study the South Atlantic Anomaly (SAA) position, average count rate, and surface size, as well as its evolution from June 2017 to March 2024. We confirm the anti-correlation between the particle count rate obtained by particle monitors and the solar activity, as well as the anti-correlation between the evolution of the SAA surface size and the solar activity. Furthermore, this study confirms earlier measurements of a westward drift of the SAA with a rate of <span><math><mn>0.343</mn><mo>±</mo><msup><mrow><mn>0.002</mn></mrow><mrow><mi>o</mi></mrow></msup></math></span>/yr in longitude. However, it reveals a smaller northward drift with a rate of <span><math><mn>0.028</mn><mo>±</mo><msup><mrow><mn>0.002</mn></mrow><mrow><mi>o</mi></mrow></msup></math></span>/yr in latitude. Two irregular drifts both in longitude and latitude were observed. We suggest that the irregular drifts may be not driven by solar cycle variation of the atmosphere but may be associated with geomagnetic jerks.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 187-193"},"PeriodicalIF":10.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422648","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}

{"title":"Role of decoupling process on the configurations of compact stars induced by Thomas-Fermi dark matter with null complexity in f(T) gravity","authors":"S.K. Maurya ,&nbsp;Jitendra Kumar ,&nbsp;Sweeti Kiroriwal","doi":"10.1016/j.jheap.2024.09.012","DOIUrl":"10.1016/j.jheap.2024.09.012","url":null,"abstract":"<div><div>Our goal in this work is to find an anisotropic solution for a self-bound compact object composed of dark matter with a null complexity factor in <span><math><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></math></span>-gravity theory. We use a well-known gravitational decoupling via complete geometric deformation (CGD) technique to examine the role of decoupling parameters on the configuration of compact objects. Initially, we derive the null complexity condition for <span><math><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></math></span>-gravity decoupled system which leads to a relation between gravitational potentials. Next, we apply the CGD approach to split the decoupled system into two subsystems. The initial system refers to a pure <span><math><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></math></span> gravity system consisting of an isotropic fluid distribution, where the isotropy criterion is equivalent to the condition in Einstein's gravity. The solution of the first system is solved through the Vlasenk-Pronin space-time metrics while the second system associated with the deformation function is solved by the density constraints method by mimicking a new source with Thomas-Fermi dark matter density profile that generates the anisotropy in the decoupled system. The physical validity of the anisotropic solution is checked by the graphical analysis of the pressure, density, energy, and stability conditions. We have also shown the effect of torsion and decoupling parameters on the configuration of anisotropic compact objects. The energy exchange (Δ<em>E</em>) of fluid distribution is also discussed. We found that Δ<em>E</em> is positive throughout the stellar configuration, which implies that energy is effectively transmitted to the surrounding environment.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 194-209"},"PeriodicalIF":10.2,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422645","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}

{"title":"Dual effect of string cloud and dark matter halos on particle motions, shadows and epicyclic oscillations around Schwarzschild black holes","authors":"Rui-Yan Chen ,&nbsp;Faisal Javed ,&nbsp;G. Mustafa ,&nbsp;S.K. Maurya ,&nbsp;Saibal Ray","doi":"10.1016/j.jheap.2024.09.010","DOIUrl":"10.1016/j.jheap.2024.09.010","url":null,"abstract":"<div><div>In this work, we study the particle dynamics, shadows and quasi-periodic oscillations around the Schwarzschild black hole with three different dark matter halos and string cloud parameters. The motion of particles is considered with the string cloud parameter <em>α</em> and investigated for massive and massless particles. The photon orbits and inner stable circular orbits of these black holes are obtained from the effective potential. The black hole shadows are calculated using three different dark matter halos. The shadow radius of these black holes increases compared to a pure Schwarzschild black hole for different values of the string cloud parameter. Further, quasi-periodic oscillations are also discussed in the current analysis. Our study examines how the radial profiles of orbital and radial harmonic oscillation frequencies change with the string cloud parameter. This study examines the major properties of test particle's quasi-periodic oscillations near stable circular orbits in the black hole equatorial plane. Our findings indicate that observational tests for black holes influenced by dark matter halos and cloud strings are also feasible and viable.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 172-186"},"PeriodicalIF":10.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422644","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}

{"title":"Conservative wormholes in generalized κ(R,T)- function","authors":"Ksh. Newton Singh ,&nbsp;G.R.P. Teruel ,&nbsp;S.K. Maurya ,&nbsp;Tanmoy Chowdhury ,&nbsp;Farook Rahaman","doi":"10.1016/j.jheap.2024.09.009","DOIUrl":"10.1016/j.jheap.2024.09.009","url":null,"abstract":"<div><div>We present an exhaustive study of wormhole configurations in <span><math><mi>κ</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span> gravity with linear and non-linear functions. The model assumed Morris-Thorne spacetime where the redshift and shape functions linked with the matter contain and geometry of the spacetime through non-covariant conservation equation of the stress-energy tensor. The first solution was explored assuming a constant redshift function that leads to a wormhole (WH) which is asymptotically non-flat. The remaining solutions were explored in two cases. Firstly, assuming a linear equation of state <span><math><mi>p</mi><mo>(</mo><mi>r</mi><mo>)</mo><mo>=</mo><mi>ω</mi><mi>ρ</mi><mo>(</mo><mi>r</mi><mo>)</mo></math></span> along with different forms of <span><math><mi>κ</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span>-function. This proved enough to derive a shape function of the form <span><math><mi>b</mi><mo>(</mo><mi>r</mi><mo>)</mo><mo>=</mo><msub><mrow><mi>r</mi></mrow><mrow><mn>0</mn></mrow></msub><msup><mrow><mo>(</mo><mfrac><mrow><msub><mrow><mi>r</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow><mrow><mi>r</mi></mrow></mfrac><mo>)</mo></mrow><mrow><mn>1</mn><mo>/</mo><mi>ω</mi></mrow></msup></math></span>. Secondly, by assuming specific choices of the shape function consistent with the wormhole configuration requirements. All the solutions fulfill flare-out condition, asymptotically flat and supported by phantom energy. Further, the embedding surface and its revolution has been generated using numerical method to see how the length of the throat is affected of the coupling parameters through <span><math><mi>κ</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span> function. At the end, we have also calculated the average null energy condition, which is satisfied by all the WH models signifying minimum exotic matter is required to open the WH throats.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 132-145"},"PeriodicalIF":10.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422646","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}

{"title":"Constraints on anisotropic properties of the universe in f(Q,T) gravity theory","authors":"A. Zhadyranova ,&nbsp;M. Koussour ,&nbsp;V. Zhumabekova ,&nbsp;O. Donmez ,&nbsp;S. Muminov ,&nbsp;J. Rayimbaev","doi":"10.1016/j.jheap.2024.09.008","DOIUrl":"10.1016/j.jheap.2024.09.008","url":null,"abstract":"<div><div>Motivated by anomalies in cosmic microwave background observations, we investigate the implications of <span><math><mi>f</mi><mo>(</mo><mi>Q</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span> gravity in Bianchi type-I spacetime, aiming to characterize the universe's spatially homogeneous and anisotropic properties. By using a linear combination of non-metricity <em>Q</em> and the energy-momentum tensor trace <em>T</em>, we parametrize the deceleration parameter and derive the Hubble solution, which we then impose in the Friedmann equations of <span><math><mi>f</mi><mo>(</mo><mi>Q</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span> gravity. Bayesian analysis is employed to find the best-fit values of model parameters, with <span><math><mn>1</mn><mo>−</mo><mi>σ</mi></math></span> and <span><math><mn>2</mn><mo>−</mo><mi>σ</mi></math></span> contour plots illustrating the constraints from observational data, including <span><math><mi>H</mi><mo>(</mo><mi>z</mi><mo>)</mo></math></span> data and the Pantheon+ sample. Our analysis reveals a transition from a decelerated to an accelerated expansion phase, with the present deceleration parameter indicating an accelerating universe. The energy density gradually decreases over time, approaching zero for the present and future, indicating continuous expansion. The anisotropic pressure, initially notably negative, transitions to slightly negative values, suggesting the presence of dark energy. The evolving equation of state parameter <em>ω</em> exhibits behavior akin to phantom energy, influenced by spacetime anisotropy. Violations of the null energy condition and the strong energy condition imply phantom-like behavior and accelerated expansion.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 123-131"},"PeriodicalIF":10.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323014","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}

{"title":"Bridging simulations of kink instability in relativistic magnetized jets with radio emission and polarisation","authors":"Nikita Upreti ,&nbsp;Bhargav Vaidya ,&nbsp;Amit Shukla","doi":"10.1016/j.jheap.2024.09.007","DOIUrl":"10.1016/j.jheap.2024.09.007","url":null,"abstract":"<div><div>Relativistic outflows emanating from active galactic nuclei can extend up to kiloparsec scales in length, displaying a variety of complex morphologies. This study explores the intricate morphologies of such relativistic jets, mainly focusing on creating a bridge between magnetic instabilities in jets with observational signatures from complex radio galaxies. In particular, we aim to study the role of dynamical instabilities in forming distinctive morphological features by employing 3D relativistic magnetohydrodynamic (RMHD) simulations of rotating jets. Our simulations have further used the hybrid Eulerian-Lagrangian framework of the <span>PLUTO</span> code and generated the synthetic synchrotron emission and polarisation maps to compare with the observed signatures. Our analysis based on simulations of a continuously injected jet suggests that current-driven instabilities, notably the <span><math><mo>|</mo><mi>m</mi><mo>|</mo><mo>=</mo><mn>1</mn></math></span> mode, generate ribs-like structures that are seen in some of the recent radio galaxies using MeerKat, e.g. <em>MysTail</em>. In our contrasting simulations of the restarted jet, the kink-instability driven ribs-like structures were formed relatively near the nozzle. In both cases, the jet dissipates its pre-existing magnetic energy through these instabilities, transitioning to a more kinetic energy dominant state. The turbulent structures resulting from this dissipation phase are filamentary and resemble the tethers as observed for the case of <em>MysTail</em>. This pilot study essentially provides a plausible qualitative explanation by bridging simulations of kink instability to produce synthetic radio features resembling the observed complex radio morphology of <em>MysTail</em>.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 146-163"},"PeriodicalIF":10.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422647","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}

{"title":"Evidence for extreme PeV cosmic ray acceleration from LHAASO","authors":"Siming Liu","doi":"10.1016/j.jheap.2024.09.006","DOIUrl":"10.1016/j.jheap.2024.09.006","url":null,"abstract":"<div><div>It is well-known that cosmic rays (CRs) as charged high-energy particles need to be accelerated by electric fields induced by magnetic fields in varieties of astrophysical environments. Due to the highly conductive nature of astrophysical plasmas, large scale electric fields can only exist in some peculiar circumstances, such as perpendicular shocks, jets, and spinning misaligned magnetic dipoles. Observational evidence for CR acceleration by such large scale electric fields is obscure since its characteristics haven't been explored extensively. The first results from the Large High Altitude Air Shower Observatory (LHAASO) imply that although PeV particles may be accelerated in varieties of ultra-high-energy (UHE) <em>γ</em>-ray sources, they likely escape from their sites of acceleration effectively giving rise to UHE <em>γ</em>-ray spectra softer than that of the diffuse <em>γ</em>-rays from the galactic plane. The all-particle energy spectrum and mean of the logarithmic mass of PeV CRs also suggest a new hard CR spectral component near the spectral knee that can be associated with CRs escaping from their site of acceleration and producing the diffuse <em>γ</em>-ray emission. The drift of high-energy particles along large scale electric fields may account for the acceleration of PeV CRs explaining these LHAASO results.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 116-122"},"PeriodicalIF":10.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311049","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}