Pub Date : 2024-06-08DOI: 10.1016/j.newast.2024.102263
Marco Immanuel B. Rivera , Reinabelle C. Reyes
The future space-borne Laser Interferometer Space Antenna (LISA) is expected to detect gravitational waves (GW) from Extreme Mass Ratio Inspiral (EMRI) binaries which may live in nontrivial environments such as accretion disks. In this work, we apply the Fisher matrix Principal Component Analysis (PCA) method to assess how well LISA observations can jointly constrain the source parameters and environmental densities around EMRIs. Specifically, we calculate the Fisher matrix from the post-Newtonian parameters of an EMRI binary embedded in a fluid with a constant density profile. We determine that the most dominant measurable parameter combination is dominated by contributions from environmental effects, namely, gravitational drag, accretion, and gravitational pull (in order of contribution). The proposed reparameterization of the PN parameters can be used to improve the power and efficiency of future detection and parameter estimation methods.
未来的星载激光干涉仪空间天线(LISA)有望探测到来自极端质量比激发(EMRI)双星的引力波(GW),这些双星可能生活在吸积盘等非简单环境中。在这项工作中,我们应用费舍尔矩阵主成分分析(PCA)方法来评估 LISA 观测能在多大程度上共同约束 EMRI 周围的源参数和环境密度。具体来说,我们根据嵌入恒定密度曲线流体中的 EMRI 双星的后牛顿参数计算费雪矩阵。我们确定,最主要的可测量参数组合是由环境效应贡献的,即引力拖拽、吸积和引力(按贡献大小排序)。提议的 PN 参数重新参数化可以用来提高未来探测和参数估计方法的功率和效率。
{"title":"Measurable parameter combinations of environmentally-dephased EMRI gravitational-wave signals","authors":"Marco Immanuel B. Rivera , Reinabelle C. Reyes","doi":"10.1016/j.newast.2024.102263","DOIUrl":"10.1016/j.newast.2024.102263","url":null,"abstract":"<div><p>The future space-borne Laser Interferometer Space Antenna (LISA) is expected to detect gravitational waves (GW) from Extreme Mass Ratio Inspiral (EMRI) binaries which may live in nontrivial environments such as accretion disks. In this work, we apply the Fisher matrix Principal Component Analysis (PCA) method to assess how well LISA observations can jointly constrain the source parameters and environmental densities around EMRIs. Specifically, we calculate the Fisher matrix from the post-Newtonian parameters of an EMRI binary embedded in a fluid with a constant density profile. We determine that the most dominant measurable parameter combination is dominated by contributions from environmental effects, namely, gravitational drag, accretion, and gravitational pull (in order of contribution). The proposed reparameterization of the PN parameters can be used to improve the power and efficiency of future detection and parameter estimation methods.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141393619","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 : 2024-06-04DOI: 10.1016/j.newast.2024.102261
R. Torres , T. Grismayer , F. Cruz , R.A. Fonseca , L.O. Silva
We present ab initio global general-relativistic Particle-in-cell (GR-PIC) simulations of compact millisecond neutron star magnetospheres in the axisymmetric aligned rotator configuration. We investigate the role of GR and plasma supply on the polar cap particle acceleration efficiency – the precursor of coherent radio emission – employing a new module for the PIC code OSIRIS, designed to model plasma dynamics around compact objects with fully self-consistent GR effects. We provide a detailed description of the main sub-algorithms of the novel PIC algorithm, including a charge-conserving current deposit scheme for curvilinear coordinates. We demonstrate efficient particle acceleration in the polar caps of compact neutron stars with denser magnetospheres, numerically validating the spacelike current extension provided by force-free models. We show that GR relaxes the minimum required poloidal magnetospheric current for the transition of the polar cap to the accelerator regime, thus justifying the observation of weak pulsars beyond the expected death line. We denote that spin-down luminosity intermittency and radio pulse nullings for older pulsars might arise from the interplay between the polar and outer gaps. Also, narrower radio beams are expected for weaker low-obliquity pulsars.
我们介绍了对轴对称对齐转子构型的紧凑型毫秒中子星磁层进行的全局广义相对论粒子入胞(GR-PIC)模拟。我们利用 PIC 代码 OSIRIS 的一个新模块研究了 GR 和等离子体供应对极盖粒子加速效率(相干射电发射的前兆)的作用,该模块旨在利用完全自洽的 GR 效应模拟紧凑天体周围的等离子体动力学。我们详细介绍了新型 PIC 算法的主要子算法,包括曲线坐标的电荷守恒电流沉积方案。我们证明了粒子在具有较密集磁层的紧凑中子星极盖中的高效加速,从数值上验证了无力模型所提供的类似于空间的电流扩展。我们表明,GR 放松了极盖过渡到加速器机制所需的最小极磁层电流,从而证明了在预期死亡线之外观测到弱脉冲星是合理的。我们指出,较老脉冲星的自旋下降光度间歇和射电脉冲无效可能是由于极隙和外隙之间的相互作用造成的。另外,较弱的低倾脉冲星的射电波束预计会更窄。
{"title":"OSIRIS-GR: General relativistic activation of the polar cap of a compact neutron star","authors":"R. Torres , T. Grismayer , F. Cruz , R.A. Fonseca , L.O. Silva","doi":"10.1016/j.newast.2024.102261","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102261","url":null,"abstract":"<div><p>We present ab initio global general-relativistic Particle-in-cell (GR-PIC) simulations of compact millisecond neutron star magnetospheres in the axisymmetric aligned rotator configuration. We investigate the role of GR and plasma supply on the polar cap particle acceleration efficiency – the precursor of coherent radio emission – employing a new module for the PIC code OSIRIS, designed to model plasma dynamics around compact objects with fully self-consistent GR effects. We provide a detailed description of the main sub-algorithms of the novel PIC algorithm, including a charge-conserving current deposit scheme for curvilinear coordinates. We demonstrate efficient particle acceleration in the polar caps of compact neutron stars with denser magnetospheres, numerically validating the spacelike current extension provided by force-free models. We show that GR relaxes the minimum required poloidal magnetospheric current for the transition of the polar cap to the accelerator regime, thus justifying the observation of weak pulsars beyond the expected death line. We denote that spin-down luminosity intermittency and radio pulse nullings for older pulsars might arise from the interplay between the polar and outer gaps. Also, narrower radio beams are expected for weaker low-obliquity pulsars.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624000757/pdfft?md5=4b7e74c6e0596423df64b16f4a75d011&pid=1-s2.0-S1384107624000757-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141291525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1016/j.newast.2024.102258
W.H. Elsanhoury
Here, we report the kinematical parameters of inner-halo hot subdwarfs located within at high Galactic latitudes . The study included three program stars for one of the extreme He-rich groups (eHe-1) with eccentricity (e= 0.65) and the z-component of the angular momentum (Jz = 4288.66 kpc km s−1), the inner halo program I with 121 points and their subsections, i.e. inner halo program II (sdB; 79 points) with and inner halo program III (sdO; 42 points) with . First, we calculated the spatial velocities ( along the Galactic coordinates (i.e., 25.73 ± ± 5.07, 28.79 ± 5.37, −14.51 ± 3.81) and their dispersion velocities = (161.94 ± 12.73, 140.31 ± 11.85, 101.57 ± 10.08) and subsequently their subsections sdB and sdO. Second, we calculated the vertex longitudes and the Solar motion as well as their subsections. Finally, based on the kinematic relation of the ratio
{"title":"Kinematical and ellipsoidal properties of the inner-halo hot subdwarfs observed in Gaia DR3 and LAMOST DR7","authors":"W.H. Elsanhoury","doi":"10.1016/j.newast.2024.102258","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102258","url":null,"abstract":"<div><p>Here, we report the kinematical parameters of inner-halo hot subdwarfs located within <span><math><mrow><mo>(</mo><mrow><mi>d</mi><mo>≤</mo><mn>15</mn><mrow><mspace></mspace><mtext>kpc</mtext></mrow></mrow><mo>)</mo></mrow></math></span> at high Galactic latitudes <span><math><mrow><mo>(</mo><mrow><msup><mrow><mi>b</mi></mrow><mi>o</mi></msup><mo>≥</mo><mn>20</mn></mrow><mo>)</mo></mrow></math></span>. The study included three program stars for one of the extreme He-rich groups (<em>e</em>He-1) with eccentricity (<em>e</em>= 0.65) and the z-component of the angular momentum (J<sub>z</sub> = 4288.66 kpc km <em>s</em><sup>−1</sup>), the inner halo program I with 121 points <span><math><mrow><mo>(</mo><mrow><msub><mi>T</mi><mtext>eff</mtext></msub><mo>≥</mo><mn>24</mn><mo>,</mo><mn>000</mn></mrow><mo>)</mo></mrow></math></span> and their subsections, i.e. inner halo program II (sdB; 79 points) with <span><math><mrow><mo>(</mo><mrow><mn>40</mn><mo>,</mo><mn>000</mn><mo>≥</mo><msub><mi>T</mi><mtext>eff</mtext></msub><mo>≥</mo><mn>24</mn><mo>,</mo><mn>000</mn></mrow><mo>)</mo></mrow></math></span> and inner halo program III (sdO; 42 points) with <span><math><mrow><mo>(</mo><mrow><mn>80</mn><mo>,</mo><mn>000</mn><mo>≥</mo><msub><mi>T</mi><mtext>eff</mtext></msub><mo>≥</mo><mn>40</mn><mo>,</mo><mn>000</mn></mrow><mo>)</mo></mrow></math></span>. First, we calculated the spatial velocities (<span><math><mrow><mover><mi>U</mi><mo>¯</mo></mover><mo>,</mo><mrow><mspace></mspace><mover><mi>V</mi><mo>¯</mo></mover></mrow><mo>,</mo><mrow><mspace></mspace><mover><mi>W</mi><mo>¯</mo></mover></mrow><mo>;</mo><mrow><mspace></mspace><mtext>km</mtext><mspace></mspace></mrow><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mrow><mo>)</mo></mrow></mrow></math></span> along the Galactic coordinates (i.e., 25.73 ± ± 5.07, 28.79 ± 5.37, −14.51 ± 3.81) and their dispersion velocities <span><math><mrow><mo>(</mo><mrow><msub><mi>σ</mi><mn>1</mn></msub><mo>,</mo><mspace></mspace><msub><mi>σ</mi><mn>2</mn></msub><mo>,</mo><mspace></mspace><msub><mi>σ</mi><mn>3</mn></msub><mo>;</mo><mrow><mspace></mspace><mtext>km</mtext><mspace></mspace></mrow><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><mo>)</mo></mrow></math></span> = (161.94 ± 12.73, 140.31 ± 11.85, 101.57 ± 10.08) and subsequently their subsections sdB and sdO. Second, we calculated the vertex longitudes <span><math><mrow><mo>(</mo><msub><mi>l</mi><mn>2</mn></msub><mo>)</mo></mrow></math></span> and the Solar motion <span><math><mrow><mo>(</mo><mrow><msub><mi>S</mi><mo>⊙</mo></msub><mo>=</mo><mn>41.24</mn><mrow><mspace></mspace><mspace></mspace></mrow><mn>6.42</mn><mrow><mspace></mspace><mtext>km</mtext><mspace></mspace></mrow><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><mo>)</mo></mrow></math></span> as well as their subsections. Finally, based on the kinematic relation of the ratio <span><math><mrow><mo>(</mo><mrow><msub><mi>σ</mi","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141291524","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 : 2024-06-01DOI: 10.1016/j.newast.2024.102259
Gopal Sardar, Subenoy Chakraborty
In the present work we consider three modified Chevallier–Polarski–Linder (CPL) models with considering non-cold dark matter in the background of homogeneous and isotropic FLRW space–time model. From the observational data set ((Pantheon+)+BAO+HST) we find that all the parameters involved in the models having equation of dark energy state (Model II) and (Model III) do not depend on . We also find that for all the models equation of state for dark matter is almost same and observe that Model I is more preferable than the other two proposed models.
{"title":"Observational constraints on modified CPL models considering non-cold dark matter","authors":"Gopal Sardar, Subenoy Chakraborty","doi":"10.1016/j.newast.2024.102259","DOIUrl":"10.1016/j.newast.2024.102259","url":null,"abstract":"<div><p>In the present work we consider three modified Chevallier–Polarski–Linder (CPL) models with considering non-cold dark matter in the background of homogeneous and isotropic FLRW space–time model. From the observational data set ((Pantheon+)+BAO+HST) we find that all the parameters involved in the models having equation of dark energy state <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub><mo>=</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>+</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub><mfrac><mrow><mi>a</mi></mrow><mrow><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mi>a</mi><mo>)</mo></mrow></mrow><mrow><mi>p</mi></mrow></msup></mrow></mfrac></mrow></math></span> (Model II) and <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub><mo>=</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>+</mo><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub><mfrac><mrow><mn>1</mn><mo>−</mo><mi>a</mi></mrow><mrow><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mi>a</mi><mo>)</mo></mrow></mrow><mrow><mi>p</mi></mrow></msup></mrow></mfrac></mrow></math></span> (Model III) do not depend on <span><math><mi>p</mi></math></span>. We also find that for all the models equation of state for dark matter is almost same and observe that Model I is more preferable than the other two proposed models.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141277508","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 : 2024-05-31DOI: 10.1016/j.newast.2024.102254
Jian-Fei Liu , Kai Li , Xu Chen , Ke-Xin Li , Fei Liu , Xing Gao , Guo-You Sun
We analyzed the light curve of the total eclipse contact binary V1320 Cas, obtained reliable photometric solutions, confirmed it to be a W-type contact binary with a mass ratio of 3.404 and a contact degree of 23.9%, a cool spot is discovered on the less massive component. Orbital period analysis indicates that the period of V1320 Cas is decreasing at a rate of day yr−1, superimposed with a cyclic modulation with a period of 1.425 yr, long-term period decrease may be caused by the combination of mass transfer and angular momentum loss, and the cyclic modulation may be caused by the third companion. Using the photometric solutions and Gaia distance, we calculated the absolute physical parameters and plotted mass-luminosity and mass–radius diagrams to analyze the evolutionary status of V1320 Cas, the more massive component is a main sequence star, while the less massive component has higher luminosity and radius than those of main sequence stars with the same mass. With the decreasing orbital period, the two components of V1320 Cas will be gradually closer, while the binary may evolve toward deep contact.
我们分析了日全食接触双星V1320 Cas的光变曲线,获得了可靠的光度解,确认它是一颗W型接触双星,质量比为3.404,接触度为23.9%,在质量较小的部分发现了一个冷斑。轨道周期分析表明,V1320 Cas的周期以dPdt=1.78×10-7 day yr-1的速率下降,并叠加有周期为1.425年的周期调制,长期周期下降可能是由质量转移和角动量损失共同引起的,而周期调制可能是由第三伴星引起的。利用测光解和盖亚距离,我们计算了V1320 Cas的绝对物理参数,并绘制了质量-光度图和质量-半径图,分析了V1320 Cas的演化状况,其中质量较大的部分是一颗主序星,而质量较小的部分的光度和半径都高于相同质量的主序星。随着轨道周期的减小,V1320 Cas 的两部分会逐渐靠近,而双星可能会向深度接触演化。
{"title":"Spectroscopic and photometric investigations of the totally eclipsing contact binary V1320 Cas","authors":"Jian-Fei Liu , Kai Li , Xu Chen , Ke-Xin Li , Fei Liu , Xing Gao , Guo-You Sun","doi":"10.1016/j.newast.2024.102254","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102254","url":null,"abstract":"<div><p>We analyzed the light curve of the total eclipse contact binary V1320 Cas, obtained reliable photometric solutions, confirmed it to be a W-type contact binary with a mass ratio of 3.404 and a contact degree of 23.9%, a cool spot is discovered on the less massive component. Orbital period analysis indicates that the period of V1320 Cas is decreasing at a rate of <span><math><mrow><mfrac><mrow><mi>d</mi><mi>P</mi></mrow><mrow><mi>d</mi><mi>t</mi></mrow></mfrac><mo>=</mo><mn>1</mn><mo>.</mo><mn>78</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></math></span> day yr<sup>−1</sup>, superimposed with a cyclic modulation with a period of 1.425 yr, long-term period decrease may be caused by the combination of mass transfer and angular momentum loss, and the cyclic modulation may be caused by the third companion. Using the photometric solutions and Gaia distance, we calculated the absolute physical parameters and plotted mass-luminosity and mass–radius diagrams to analyze the evolutionary status of V1320 Cas, the more massive component is a main sequence star, while the less massive component has higher luminosity and radius than those of main sequence stars with the same mass. With the decreasing orbital period, the two components of V1320 Cas will be gradually closer, while the binary may evolve toward deep contact.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141250358","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}
This paper presents properties of the intracluster medium (ICM) in the environment of a cool core cluster Abell 2566 (redshift 0.08247) based on the analysis of 20 ks Chandra X-ray data. 2D imaging analysis of the Chandra data from this cluster revealed spiral structures in the morphology of X-ray emission from within the central 109 kpc formed due to gas sloshing. This analysis also witness sharp edges in the surface brightness distribution along the south-east and north-west of the X-ray peaks at 41.6 kpc and 77.4 kpc, respectively. Spectral analysis of 0.5 – 7 keV X-ray photons along these discontinuities exhibited sharp temperature jumps from 2.3 to 3.1 keV and 1.8 to 2.8 keV, respectively, with consistency in the pressure profiles, implying their association with cold fronts due to gas sloshing of the gas. Further confirmation for such an association was provided by the deprojected broken power-law density function fit to the surface brightness distribution along these wedge shaped sectorial regions. This study also witness an offset of 4.6 (6.8 kpc) between the BCG and the X-ray peak, and interaction of the BCG with a sub-system in the central region, pointing towards the origin of the spiral structure due to a minor merger.
本文根据对 20 ks 钱德拉 X 射线数据的分析,介绍了冷核星团 Abell 2566(红移 z = 0.08247)环境中星团内介质(ICM)的特性。对该星团的钱德拉数据进行的二维成像分析表明,在中心 109 kpc 范围内的 X 射线辐射形态中,存在着由于气体荡动而形成的螺旋结构。该分析还发现,在 41.6 kpc 和 77.4 kpc 的 X 射线峰值的东南和西北方向,表面亮度分布存在尖锐的边缘。对沿这些不连续面的 0.5-7 千伏 X 射线光子进行的光谱分析显示,温度分别从 2.3 千伏跃升到 3.1 千伏,从 1.8 千伏跃升到 2.8 千伏,而且压力剖面一致,这意味着它们与气体荡动引起的冷锋有关。对这些楔形扇形区域的表面亮度分布进行的破碎幂律密度函数拟合进一步证实了这种关联。这项研究还发现 BCG 与 X 射线峰之间存在 4.6′′(6.8 kpc)的偏移,BCG 与中心区域的一个子系统发生了相互作用,这表明螺旋结构的起源是由于一次小规模合并造成的。
{"title":"Sloshing cold fronts in galaxy cluster Abell 2566","authors":"S.K. Kadam , S.S. Sonkamble , N.D. Vagshette , M.K. Patil","doi":"10.1016/j.newast.2024.102253","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102253","url":null,"abstract":"<div><p>This paper presents properties of the intracluster medium (ICM) in the environment of a cool core cluster Abell 2566 (redshift <span><math><mi>z</mi></math></span> <span><math><mo>=</mo></math></span> 0.08247) based on the analysis of 20 ks <em>Chandra</em> X-ray data. 2D imaging analysis of the <em>Chandra</em> data from this cluster revealed spiral structures in the morphology of X-ray emission from within the central 109 kpc formed due to gas sloshing. This analysis also witness sharp edges in the surface brightness distribution along the south-east and north-west of the X-ray peaks at 41.6 kpc and 77.4 kpc, respectively. Spectral analysis of 0.5 – 7 keV X-ray photons along these discontinuities exhibited sharp temperature jumps from 2.3 to 3.1 keV and 1.8 to 2.8 keV, respectively, with consistency in the pressure profiles, implying their association with cold fronts due to gas sloshing of the gas. Further confirmation for such an association was provided by the deprojected broken power-law density function fit to the surface brightness distribution along these wedge shaped sectorial regions. This study also witness an offset of 4.6<span><math><msup><mrow></mrow><mrow><mo>′</mo><mo>′</mo></mrow></msup></math></span> <!--> <!-->(6.8 kpc) between the BCG and the X-ray peak, and interaction of the BCG with a sub-system in the central region, pointing towards the origin of the spiral structure due to a minor merger.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141240087","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 : 2024-05-28DOI: 10.1016/j.newast.2024.102256
Riaz Ahmed
This study explores the impact of gravity, where is the Gauss Bonnet invariant and is the trace of the energy–momentum tensor, on the adiabatic anisotropic spherical gravitating source under the expansion-free condition. We coupled the relativistic matter with spherical symmetric structure by applying Gauss–Bonnet model with a linear trace. To derive the collapse equation, we used the perturbation method on the field equations and the contracted Bianchi identities. The dynamics of instability range is depicted in Newtonian () and post-Newtonian (pN) regimes. Furthermore, instead of using the adiabatic index, we establish the instability range by looking at the density profile and anisotropic pressure configuration. We investigate the analytic solutions that meets the expansion-free condition. Finally, we have successfully achieved the original results obtained by Herrera et al. (2012) in General Relativity by setting in proposed cosmological model.
本研究探讨了 f(G,T) 引力在无膨胀条件下对绝热各向异性球形引力源的影响,其中 G 是高斯-波奈不变式,T 是能动张量的迹。我们采用 f(G,T)=αGn+λT 高斯-波内特模型与线性迹线将相对论物质与球对称结构耦合。为了推导坍缩方程,我们使用了场方程的扰动法和收缩的比安奇等式。在牛顿(N)和后牛顿(pN)状态下描述了不稳定范围的动力学。此外,我们不使用绝热指数,而是通过观察密度剖面和各向异性压力配置来确定不稳定范围。我们研究了满足无膨胀条件的解析解。最后,我们在提出的宇宙学模型中设定α=λ=0,成功地实现了埃雷拉等人(2012)在广义相对论中获得的原始结果。
{"title":"Effects of expansion-free condition on adiabatic collapse in f(G,T) gravity","authors":"Riaz Ahmed","doi":"10.1016/j.newast.2024.102256","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102256","url":null,"abstract":"<div><p>This study explores the impact of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G,T</mi><mo>)</mo></mrow></mrow></math></span> gravity, where <span><math><mi>G</mi></math></span> is the Gauss Bonnet invariant and <span><math><mi>T</mi></math></span> is the trace of the energy–momentum tensor, on the adiabatic anisotropic spherical gravitating source under the expansion-free condition. We coupled the relativistic matter with spherical symmetric structure by applying <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>G,T</mi><mo>)</mo></mrow><mo>=</mo><mi>α</mi><msup><mrow><mi>G</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>+</mo><mi>λ</mi><mi>T</mi></mrow></math></span> Gauss–Bonnet model with a linear trace. To derive the collapse equation, we used the perturbation method on the field equations and the contracted Bianchi identities. The dynamics of instability range is depicted in Newtonian (<span><math><mi>N</mi></math></span>) and post-Newtonian (pN) regimes. Furthermore, instead of using the adiabatic index, we establish the instability range by looking at the density profile and anisotropic pressure configuration. We investigate the analytic solutions that meets the expansion-free condition. Finally, we have successfully achieved the original results obtained by Herrera et al. (2012) in General Relativity by setting <span><math><mrow><mi>α</mi><mo>=</mo><mi>λ</mi><mo>=</mo><mn>0</mn></mrow></math></span> in proposed cosmological model.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141291523","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 : 2024-05-28DOI: 10.1016/j.newast.2024.102260
M.Javed Idrisi , M.Shahbaz Ullah , Worku Tenna , M.Tauheed Khan , M.Faisal Khan , Mustafa Kamal
This manuscript thoroughly explores the dynamics of a test particle around out-of-plane equilibrium points within the circular restricted eight-body problem. This particular scenario features a central primary emitting radiation, and it is a specific case derived from Kalvouridis and Hadjifotinou's analysis of Maxwell's ring problem in 2011. Our investigation uncovers two symmetrical out-of-plane equilibrium points denoted as E1,2(0, 0, z0), where z0 is determined by the equation z0 = ±a tanυ; υ = arcsin[(‒q/6)1/3], with q falling within the range (‒6, 0). Here, a denotes the radius of the circular orbit of peripheral primaries around the radiating central primary, and q signifies the radiation factor due to the central primary. Significantly, for a critical radiation factor value, qc = ‒3/√2, the equilibrium points E1,2 precisely align along the z-axis on the sphere of radius a and centered at the central primary. Within the intervals of ‒6 < q < qc and qc < q < 0, equilibrium points E1 and E2 are situated outside and inside the mentioned sphere on the z-axis, respectively. Specifically, for q ≤ qc, | z0 | ≤ a, while for q > qc, | z0 | > a. The study further explores the linear stability of E1,2. By analyzing characteristic curves derived from the variational equations of motion for infinitesimal mass around these equilibrium points, particularly for q values of ‒3/4, ‒3/√2, and ‒9√3/4, we observe that these out-of-plane equilibria, E1,2, demonstrate linear instability. This insight provides a comprehensive understanding of the intricate dynamics in this specific multi-body problem. Finally, the research illustrates periodic orbits surrounding the out-of-plane equilibrium point for specific values of q.
{"title":"Out-of-plane dynamics: a study within the circular restricted eight-body framework","authors":"M.Javed Idrisi , M.Shahbaz Ullah , Worku Tenna , M.Tauheed Khan , M.Faisal Khan , Mustafa Kamal","doi":"10.1016/j.newast.2024.102260","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102260","url":null,"abstract":"<div><p>This manuscript thoroughly explores the dynamics of a test particle around out-of-plane equilibrium points within the circular restricted eight-body problem. This particular scenario features a central primary emitting radiation, and it is a specific case derived from Kalvouridis and Hadjifotinou's analysis of Maxwell's ring problem in 2011. Our investigation uncovers two symmetrical out-of-plane equilibrium points denoted as <em>E</em><sub>1,2</sub>(0, 0, <em>z</em><sub>0</sub>), where <em>z</em><sub>0</sub> is determined by the equation <em>z</em><sub>0</sub> = ±<em>a</em> tanυ; υ = arcsin[(‒<em>q</em>/6)<sup>1/3</sup>], with <em>q</em> falling within the range (‒6, 0). Here, <em>a</em> denotes the radius of the circular orbit of peripheral primaries around the radiating central primary, and <em>q</em> signifies the radiation factor due to the central primary. Significantly, for a critical radiation factor value, <em>q<sub>c</sub></em> = ‒3/√2, the equilibrium points <em>E</em><sub>1,2</sub> precisely align along the <em>z</em>-axis on the sphere of radius <em>a</em> and centered at the central primary. Within the intervals of ‒6 < <em>q</em> < <em>q<sub>c</sub></em> and <em>q<sub>c</sub></em> < <em>q</em> < 0, equilibrium points <em>E</em><sub>1</sub> and <em>E</em><sub>2</sub> are situated outside and inside the mentioned sphere on the <em>z</em>-axis, respectively. Specifically, for <em>q</em> ≤ <em>q<sub>c</sub></em>, | <em>z</em><sub>0</sub> | ≤ <em>a</em>, while for <em>q</em> > <em>q<sub>c</sub></em>, | <em>z</em><sub>0</sub> | > <em>a</em>. The study further explores the linear stability of <em>E</em><sub>1,2</sub>. By analyzing characteristic curves derived from the variational equations of motion for infinitesimal mass around these equilibrium points, particularly for <em>q</em> values of ‒3/4, ‒3/√2, and ‒9√3/4, we observe that these out-of-plane equilibria, <em>E</em><sub>1,2</sub>, demonstrate linear instability. This insight provides a comprehensive understanding of the intricate dynamics in this specific multi-body problem. Finally, the research illustrates periodic orbits surrounding the out-of-plane equilibrium point for specific values of <em>q</em>.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141240141","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 : 2024-05-25DOI: 10.1016/j.newast.2024.102255
Iffat Fayyaz , Tayyaba Naz , Adnan Malik
The purpose of this study is to elaborate on the Morris–Thorne wormhole notion by creating a detailed model of a charged wormhole shape function. The classical embedding theory, which has played a significant role in the general theory of relativity, accomplishes this objective. Here, we assume redshift function along with charge i.e. and . For this particular choice, the surface redshift function remains positive and finite everywhere even for the larger range of radial coordinate . In wormhole geometry, the violation of Null energy condition have a crucial role which leads to the exotic matter. We examined our solutions through energy bounds (Null, Weak and Strong energy bounds) to check their stable state and its viability. Interestingly, in present work we analyze that the presence of electric charge amplify the results and provides the traversable charged wormhole solutions without exotic matter near the throat in the context of general theory of relativity.
{"title":"Fate of charged wormhole structures utilizing Karmarkar approach","authors":"Iffat Fayyaz , Tayyaba Naz , Adnan Malik","doi":"10.1016/j.newast.2024.102255","DOIUrl":"https://doi.org/10.1016/j.newast.2024.102255","url":null,"abstract":"<div><p>The purpose of this study is to elaborate on the Morris–Thorne wormhole notion by creating a detailed model of a charged wormhole shape function. The classical embedding theory, which has played a significant role in the general theory of relativity, accomplishes this objective. Here, we assume redshift function along with charge i.e. <span><math><mrow><mi>ψ</mi><mrow><mo>(</mo><mi>r</mi><mo>,</mo><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></mrow><mo>=</mo><mi>L</mi><mi>o</mi><mi>g</mi><mrow><mo>[</mo><mn>1</mn><mo>+</mo><mfrac><mrow><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow><mrow><msup><mrow><mi>r</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac><mo>]</mo></mrow></mrow></math></span> and <span><math><mrow><mi>Q</mi><mrow><mo>(</mo><mi>r</mi><mo>)</mo></mrow><mo>=</mo><mi>ξ</mi><msqrt><mrow><mi>r</mi></mrow></msqrt></mrow></math></span>. For this particular choice, the surface redshift function remains positive and finite everywhere even for the larger range of radial coordinate <span><math><mi>r</mi></math></span>. In wormhole geometry, the violation of Null energy condition have a crucial role which leads to the exotic matter. We examined our solutions through energy bounds (Null, Weak and Strong energy bounds) to check their stable state and its viability. Interestingly, in present work we analyze that the presence of electric charge amplify the results and provides the traversable charged wormhole solutions without exotic matter near the throat in the context of general theory of relativity.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141239252","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 : 2024-05-24DOI: 10.1016/j.newast.2024.102257
Aksana Kurhuzava
We study the radiation of the ultrarelativistic shell in the diffusion approximation, which takes place at the initial stage of a gamma-ray burst. We get the effective temperature, instantaneous and time-integrated spectra for the parabolic distribution of the initial internal energy of the shell. Also we considered the types of the equitemporal surfaces with a different type of the movement of the shell.
{"title":"Spectra and equitemporal surfaces of the photosphere of the ultrarelativistic shell as applied to Gamma-ray bursts","authors":"Aksana Kurhuzava","doi":"10.1016/j.newast.2024.102257","DOIUrl":"10.1016/j.newast.2024.102257","url":null,"abstract":"<div><p>We study the radiation of the ultrarelativistic shell in the diffusion approximation, which takes place at the initial stage of a gamma-ray burst. We get the effective temperature, instantaneous and time-integrated spectra for the parabolic distribution of the initial internal energy of the shell. Also we considered the types of the equitemporal surfaces with a different type of the movement of the shell.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141138236","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}