Lina Zhang, Qiyuan Pan, Yun Soo Myung, De-Cheng Zou
We study the spontaneous scalarization of Bardeen black holes, whose tachyonic instability triggers the formation of scalarized charged black holes (SCBHs). In this case, we find infinite ($n=0,1,2,cdots$) branches of SCBHs with magnetic charge $g$. The $n = 0$ branch of SCBHs can be found for the coupling parameter $alpha geq alpha_{n=0}(g)$ with both quadratic (1-$alpha varphi^2$) and exponential ($e^{-alpha varphi^2}$) couplings, where $alpha_{n=0}(g)$ represents the threshold of tachyonic instability for the Bardeen black holes. Furthermore, it is shown that the $n = 0$ branch for both couplings is stable against radial perturbations. This stability shows that this branch can be used for further observational implications.
{"title":"Spontaneous scalarization of Bardeen black holes","authors":"Lina Zhang, Qiyuan Pan, Yun Soo Myung, De-Cheng Zou","doi":"arxiv-2409.11669","DOIUrl":"https://doi.org/arxiv-2409.11669","url":null,"abstract":"We study the spontaneous scalarization of Bardeen black holes, whose\u0000tachyonic instability triggers the formation of scalarized charged black holes\u0000(SCBHs). In this case, we find infinite ($n=0,1,2,cdots$) branches of SCBHs\u0000with magnetic charge $g$. The $n = 0$ branch of SCBHs can be found for the\u0000coupling parameter $alpha geq alpha_{n=0}(g)$ with both quadratic (1-$alpha\u0000varphi^2$) and exponential ($e^{-alpha varphi^2}$) couplings, where\u0000$alpha_{n=0}(g)$ represents the threshold of tachyonic instability for the\u0000Bardeen black holes. Furthermore, it is shown that the $n = 0$ branch for both\u0000couplings is stable against radial perturbations. This stability shows that\u0000this branch can be used for further observational implications.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"263 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By utilizing the AdS/CFT correspondence and wave optics techniques, we conducted an extensive study of the imaging properties of holographic Einstein rings in the context of Anti-de Sitter (AdS) black holes (BHs) in Horndeski theory. Our results indicate that the optical characteristics of these holographic Einstein rings are significantly influenced by the observer's position, the physical parameters of the BH, the nature of the wave source, and the configuration of the optical system. Specifically, when the observer is positioned at the north pole of the AdS boundary, the holographic image prominently displays a ring structure aligning with the BH's photon sphere. We thoroughly analyzed how various physical parameters -- including the observation position, event horizon radius, temperature, and the parameter $gamma$ in Horndeski theory -- affect the holographic Einstein rings. These parameters play a crucial role in determining the rings' radius and brightness, with variations potentially causing the ring structures to deform or even transform into bright spots. Furthermore, our comparative analysis between wave optics and geometric optics reveals a strong agreement in predicting the positions and brightnesses of both the photon ring and the Einstein ring. This research offers new insights into the spacetime geometry of BHs in Horndeski theory and proposes a promising framework for exploring the gravitational duals of strongly coupled systems.
{"title":"Holographic Einstein Rings of AdS Black Holes in Horndeski Theory","authors":"Zhi Luo, Ke-Jian He, Jin Li","doi":"arxiv-2409.11885","DOIUrl":"https://doi.org/arxiv-2409.11885","url":null,"abstract":"By utilizing the AdS/CFT correspondence and wave optics techniques, we\u0000conducted an extensive study of the imaging properties of holographic Einstein\u0000rings in the context of Anti-de Sitter (AdS) black holes (BHs) in Horndeski\u0000theory. Our results indicate that the optical characteristics of these\u0000holographic Einstein rings are significantly influenced by the observer's\u0000position, the physical parameters of the BH, the nature of the wave source, and\u0000the configuration of the optical system. Specifically, when the observer is\u0000positioned at the north pole of the AdS boundary, the holographic image\u0000prominently displays a ring structure aligning with the BH's photon sphere. We\u0000thoroughly analyzed how various physical parameters -- including the\u0000observation position, event horizon radius, temperature, and the parameter\u0000$gamma$ in Horndeski theory -- affect the holographic Einstein rings. These\u0000parameters play a crucial role in determining the rings' radius and brightness,\u0000with variations potentially causing the ring structures to deform or even\u0000transform into bright spots. Furthermore, our comparative analysis between wave\u0000optics and geometric optics reveals a strong agreement in predicting the\u0000positions and brightnesses of both the photon ring and the Einstein ring. This\u0000research offers new insights into the spacetime geometry of BHs in Horndeski\u0000theory and proposes a promising framework for exploring the gravitational duals\u0000of strongly coupled systems.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. S. Agrawal, Sankarsan Tarai, B. Mishra, S. K. Tripathy
In this study, we investigate traversable wormhole solutions within the setup of $f(R,mathcal{L}_{m})$ gravity, a modified theory of gravity where the gravitational action relies upon the matter Lagrangian $mathcal{L}_{m}$ and the Ricci scalar $R$. In General Relativity (GR), stability issues in traversable wormholes necessitate the existence of exotic matter that violates the null energy condition (NEC). In contrast, we explore wormhole solutions that align with the criteria for Casimir wormholes, which do not necessarily require NEC violation. Our analysis demonstrates that in the context of $f(R,mathcal{L}_{m})$ gravity, exotic matter can sustain these wormholes. We further examine the traversability conditions of the wormhole, considering both scenarios with and without the Generalized Uncertainty Principle (GUP) correction. Additionally, the stability of the wormhole is assessed based on equilibrium conditions. Our findings suggest that $f(R,mathcal{L}_{m})$ gravity offers a viable framework for the existence of stable, traversable wormholes sustained by exotic matter, potentially expanding the landscape of viable wormhole solutions beyond the confines of GR.
{"title":"Matter Geometry Coupling and Casimir Wormhole Geometry","authors":"A. S. Agrawal, Sankarsan Tarai, B. Mishra, S. K. Tripathy","doi":"arxiv-2409.12160","DOIUrl":"https://doi.org/arxiv-2409.12160","url":null,"abstract":"In this study, we investigate traversable wormhole solutions within the setup\u0000of $f(R,mathcal{L}_{m})$ gravity, a modified theory of gravity where the\u0000gravitational action relies upon the matter Lagrangian $mathcal{L}_{m}$ and\u0000the Ricci scalar $R$. In General Relativity (GR), stability issues in\u0000traversable wormholes necessitate the existence of exotic matter that violates\u0000the null energy condition (NEC). In contrast, we explore wormhole solutions\u0000that align with the criteria for Casimir wormholes, which do not necessarily\u0000require NEC violation. Our analysis demonstrates that in the context of\u0000$f(R,mathcal{L}_{m})$ gravity, exotic matter can sustain these wormholes. We\u0000further examine the traversability conditions of the wormhole, considering both\u0000scenarios with and without the Generalized Uncertainty Principle (GUP)\u0000correction. Additionally, the stability of the wormhole is assessed based on\u0000equilibrium conditions. Our findings suggest that $f(R,mathcal{L}_{m})$\u0000gravity offers a viable framework for the existence of stable, traversable\u0000wormholes sustained by exotic matter, potentially expanding the landscape of\u0000viable wormhole solutions beyond the confines of GR.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, magnetic reconnection has attracted considerable attention as a novel energy extraction mechanism, relying on the rapid reconnection of magnetic field lines within the ergosphere. We have investigated the properties of the energy extraction via magnetic reconnection in a Konoplya-Zhidenko rotating non-Kerr black hole spacetime with an extra deformation parameter. Our results show that the positive deformation parameter expands the possible region of energy extraction and improves the maximum power, maximum efficiency, and the maximum ratio of energy extraction between magnetic reconnection and the Blandford-Znajek process. This means that in the Konoplya-Zhidenko rotating non-Kerr black hole spacetime one can extract more energy via magnetic reconnection than in the Kerr black hole case. These effects of the deformation parameter may provide valuable clues for future astronomical observations of black holes and verification of gravity theories.
{"title":"Magnetic Reconnection and Energy Extraction from a Konoplya-Zhidenko rotating non-Kerr black hole","authors":"Fen Long, Shangyun Wang, Songbai Chen, Jiliang Jing","doi":"arxiv-2409.11942","DOIUrl":"https://doi.org/arxiv-2409.11942","url":null,"abstract":"Recently, magnetic reconnection has attracted considerable attention as a\u0000novel energy extraction mechanism, relying on the rapid reconnection of\u0000magnetic field lines within the ergosphere. We have investigated the properties\u0000of the energy extraction via magnetic reconnection in a Konoplya-Zhidenko\u0000rotating non-Kerr black hole spacetime with an extra deformation parameter. Our\u0000results show that the positive deformation parameter expands the possible\u0000region of energy extraction and improves the maximum power, maximum efficiency,\u0000and the maximum ratio of energy extraction between magnetic reconnection and\u0000the Blandford-Znajek process. This means that in the Konoplya-Zhidenko rotating\u0000non-Kerr black hole spacetime one can extract more energy via magnetic\u0000reconnection than in the Kerr black hole case. These effects of the deformation\u0000parameter may provide valuable clues for future astronomical observations of\u0000black holes and verification of gravity theories.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Diego Tessainer, Antonio L. Maroto, Prado Martín-Moruno
We consider theories which break the invariance under diffeomorphisms (Diff) down to transverse diffeomorphisms (TDiff) in the matter sector, consisting of multiple scalar fields. In particular, we regard shift-symmetric models with two free TDiff scalar fields in a flat Robertson-Walker spacetime and use the perfect fluid approach to study their dynamics. As a consequence of the symmetry breaking, an effective interaction between the fields is induced from the conservation of the total energy-momentum tensor, without the necessity to introduce any explicit interacting term in the Lagrangian. We study the different single-field domination regimes and analyze the energy exchange between the fields. Thereupon, we introduce an application of these models for the description of interactions in the dark sector, and compare the theoretical predictions of our model to observational data from Type Ia supernovae.
我们考虑的理论打破了差分变形（Diff）下的不变性，在物质扇区中变成了横向差分变形（TDiff），由多个标量场组成。特别是，我们考虑了在平坦的罗伯逊-沃克时空中具有两个自由 TDiff 标量场的位移对称模型，并使用完全流体方法来研究它们的动力学。由于对称性破缺，场之间的有效相互作用是由总能量张量守恒引起的，而无需在拉格朗日中引入任何显式相互作用项。我们研究了不同的单场支配状态，并分析了场之间的能量交换。然后，我们介绍了这些模型在描述暗部门相互作用中的应用，并将我们模型的理论预测与 Ia 型超新星的观测数据进行了比较。
{"title":"Multi-field TDiff theories for cosmology","authors":"Diego Tessainer, Antonio L. Maroto, Prado Martín-Moruno","doi":"arxiv-2409.11991","DOIUrl":"https://doi.org/arxiv-2409.11991","url":null,"abstract":"We consider theories which break the invariance under diffeomorphisms (Diff)\u0000down to transverse diffeomorphisms (TDiff) in the matter sector, consisting of\u0000multiple scalar fields. In particular, we regard shift-symmetric models with\u0000two free TDiff scalar fields in a flat Robertson-Walker spacetime and use the\u0000perfect fluid approach to study their dynamics. As a consequence of the\u0000symmetry breaking, an effective interaction between the fields is induced from\u0000the conservation of the total energy-momentum tensor, without the necessity to\u0000introduce any explicit interacting term in the Lagrangian. We study the\u0000different single-field domination regimes and analyze the energy exchange\u0000between the fields. Thereupon, we introduce an application of these models for\u0000the description of interactions in the dark sector, and compare the theoretical\u0000predictions of our model to observational data from Type Ia supernovae.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"191 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Alencar, M. Nilton, Manuel E. Rodrigues, Marcos V. de S. Silva
In the framework of Simpson-Visser, the search for field sources that produce black bounces in alternative gravity theories has remained unresolved. In this paper, the first in a series exploring sources for alternative theories of gravity, we identify such a source for the $2+1$ dimensional K-gravity black bounce. The K-gravity black hole is notable for allowing asymptotically locally flat solutions in lower-dimensional spacetime, yet it possesses curvature singularities concealed within the event horizon. Using the Simpson-Visser regularization technique, we eliminate this singularity, constructing asymptotically locally flat black-bounce solutions in $2+1$ dimensions. We explore the causal structure of these solutions, identifying the conditions under which they describe regular black holes or wormholes. By calculating curvature invariants, we confirm the absence of singularities within the event horizon. Additionally, we demonstrate that, beyond non-linear electrodynamics, a non-linear scalar field is required to source the solution. Finally, we investigate the geodesic structure of this spacetime, analyzing the trajectories of both massive and massless particles. We also confirm the existence of circular orbits and assess their stability.
在辛普森-维瑟的框架内，寻找在另类引力理论中产生黑弹的场源的问题一直悬而未决。本文是探索另类引力理论场源系列的第一篇论文，我们为 2+1$ 维 K 引力黑反弹确定了这样一个场源。K引力黑洞的显著特点是允许在低维时空中出现近似局部平坦的解，但它在事件视界内隐藏着曲率奇异性。我们利用辛普森-维塞尔正则化技术消除了这种奇异性，从而在 2+1 美元维度中构建了渐近局部平坦的黑洞反弹解。我们探索了这些解的因果结构，确定了它们描述规则黑洞或虫洞的条件。通过计算曲率不变量，我们证实在偶数边界内不存在奇点。此外，我们还证明，除了非线性电动力学之外，还需要一个非线性标量场作为解的来源。最后，我们研究了这个时空的大地结构，分析了大质量和无质量粒子的轨迹。我们还证实了圆形轨道的存在，并评估了其稳定性。
{"title":"Field Sources for $f(R,R_{μν})$ Black-Bounce Solutions: The Case of K-Gravity","authors":"G. Alencar, M. Nilton, Manuel E. Rodrigues, Marcos V. de S. Silva","doi":"arxiv-2409.12101","DOIUrl":"https://doi.org/arxiv-2409.12101","url":null,"abstract":"In the framework of Simpson-Visser, the search for field sources that produce\u0000black bounces in alternative gravity theories has remained unresolved. In this\u0000paper, the first in a series exploring sources for alternative theories of\u0000gravity, we identify such a source for the $2+1$ dimensional K-gravity black\u0000bounce. The K-gravity black hole is notable for allowing asymptotically locally\u0000flat solutions in lower-dimensional spacetime, yet it possesses curvature\u0000singularities concealed within the event horizon. Using the Simpson-Visser\u0000regularization technique, we eliminate this singularity, constructing\u0000asymptotically locally flat black-bounce solutions in $2+1$ dimensions. We\u0000explore the causal structure of these solutions, identifying the conditions\u0000under which they describe regular black holes or wormholes. By calculating\u0000curvature invariants, we confirm the absence of singularities within the event\u0000horizon. Additionally, we demonstrate that, beyond non-linear electrodynamics,\u0000a non-linear scalar field is required to source the solution. Finally, we\u0000investigate the geodesic structure of this spacetime, analyzing the\u0000trajectories of both massive and massless particles. We also confirm the\u0000existence of circular orbits and assess their stability.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ultra-light primordial black holes (PBHs) with masses $M_{rm PBH}<5times 10^8mathrm{g}$ can dominate transiently the energy budget of the Universe and reheat the Universe through their evaporation taking place before Big Bang Nucleosynthesis. The isocurvature energy density fluctuations associated to the inhomogeneous distribution of a population of such PBHs can induce an abundant production of GWs due to second-order gravitational effects. In this work, we discuss the effect of primordial non-Gaussianity on the clustering properties of PBHs and study the effect of a clustered PBH population on the spectral shape of the aforementioned induced GW signal. In particular, focusing on local-type non-Gaussianity we find a double-peaked GW signal with the amplitude of the low-frequency peak being proportional to the square of the non-Gaussian parameter $tau_mathrm{NL}$. Remarkably, depending on the PBH mass $M_{rm PBH}$ and the initial abundance of PBHs at formation time, i.e. $Omega_mathrm{PBH,f}$, this double-peaked GW signal can lie well within the frequency bands of forthcoming GW detectors, namely LISA, ET, SKA and BBO, hence rendering this signal falsifiable by GW experiments and promoting it as a novel portal probing the primordial non-Gaussianity.
{"title":"Gravitational waves from primordial black hole isocurvature: the effect of non-Gaussianities","authors":"Xin-Chen He, Yi-Fu Cai, Xiao-Han Ma, Theodoros Papanikolaou, Emmanuel N. Saridakis, Misao Sasaki","doi":"arxiv-2409.11333","DOIUrl":"https://doi.org/arxiv-2409.11333","url":null,"abstract":"Ultra-light primordial black holes (PBHs) with masses $M_{rm PBH}<5times\u000010^8mathrm{g}$ can dominate transiently the energy budget of the Universe and\u0000reheat the Universe through their evaporation taking place before Big Bang\u0000Nucleosynthesis. The isocurvature energy density fluctuations associated to the\u0000inhomogeneous distribution of a population of such PBHs can induce an abundant\u0000production of GWs due to second-order gravitational effects. In this work, we\u0000discuss the effect of primordial non-Gaussianity on the clustering properties\u0000of PBHs and study the effect of a clustered PBH population on the spectral\u0000shape of the aforementioned induced GW signal. In particular, focusing on\u0000local-type non-Gaussianity we find a double-peaked GW signal with the amplitude\u0000of the low-frequency peak being proportional to the square of the non-Gaussian\u0000parameter $tau_mathrm{NL}$. Remarkably, depending on the PBH mass $M_{rm\u0000PBH}$ and the initial abundance of PBHs at formation time, i.e.\u0000$Omega_mathrm{PBH,f}$, this double-peaked GW signal can lie well within the\u0000frequency bands of forthcoming GW detectors, namely LISA, ET, SKA and BBO,\u0000hence rendering this signal falsifiable by GW experiments and promoting it as a\u0000novel portal probing the primordial non-Gaussianity.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"211 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Determining the Hubble constant (H0), a fundamental parameter describing cosmic expansion, remains a challenge due to conflicting measurements from the early and late universe. Gravitational wave (GW) observations from binary neutron star (BNS) mergers, with identified host galaxies through electromagnetic (EM) follow-up, offer an independent method to measure H0. However, this requires detection of numerous events, which could take decades with current GW detectors. LIGO-India can dramatically accelerate this effort. With sensitivity comparable to the existing LIGO detectors, its addition to the LIGO-Virgo network could increase detected events by 70%. This improvement nearly doubles when accounting for the detector's 70% duty cycle, increasing the probability of simultaneous operation of three detectors by a factor of ~2. We perform end-to-end simulations to estimate triple-coincidence detection rates and sky localization, considering realistic BNS populations, lightcurves, and EM observatory specifications. Our findings suggest LIGO-India could increase BNS events with observed kilonovae by ~2-7 times. The factor of few improvements in source localization precision with LIGO-India can allow much deeper EM follow-up campaigns (not considered in the simulations), potentially increasing the overall rate of detection of EM counterparts by a factor of ~20, which can have an enormous impact in addressing critical questions in different areas of astronomy. We evaluate the impact of LIGO-India in the context of H0 measurement and argue that it can cut down the required observation time of several decades by a factor of few and possibly to just few years with regular sensitivity upgrades.
{"title":"Assessing the potential of LIGO-India in resolving the Hubble Tension","authors":"Kanchan Soni, Aditya Vijaykumar, Sanjit Mitra","doi":"arxiv-2409.11361","DOIUrl":"https://doi.org/arxiv-2409.11361","url":null,"abstract":"Determining the Hubble constant (H0), a fundamental parameter describing\u0000cosmic expansion, remains a challenge due to conflicting measurements from the\u0000early and late universe. Gravitational wave (GW) observations from binary\u0000neutron star (BNS) mergers, with identified host galaxies through\u0000electromagnetic (EM) follow-up, offer an independent method to measure H0.\u0000However, this requires detection of numerous events, which could take decades\u0000with current GW detectors. LIGO-India can dramatically accelerate this effort.\u0000With sensitivity comparable to the existing LIGO detectors, its addition to the\u0000LIGO-Virgo network could increase detected events by 70%. This improvement\u0000nearly doubles when accounting for the detector's 70% duty cycle, increasing\u0000the probability of simultaneous operation of three detectors by a factor of ~2.\u0000We perform end-to-end simulations to estimate triple-coincidence detection\u0000rates and sky localization, considering realistic BNS populations, lightcurves,\u0000and EM observatory specifications. Our findings suggest LIGO-India could\u0000increase BNS events with observed kilonovae by ~2-7 times. The factor of few\u0000improvements in source localization precision with LIGO-India can allow much\u0000deeper EM follow-up campaigns (not considered in the simulations), potentially\u0000increasing the overall rate of detection of EM counterparts by a factor of ~20,\u0000which can have an enormous impact in addressing critical questions in different\u0000areas of astronomy. We evaluate the impact of LIGO-India in the context of H0\u0000measurement and argue that it can cut down the required observation time of\u0000several decades by a factor of few and possibly to just few years with regular\u0000sensitivity upgrades.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhi-Yuan Li, Zheng-Cheng Liang, En-Kun Li, Jian-dong Zhang, Yi-Ming Hu
In the milli-Hertz frequency band, stochastic gravitational-wave background can be composed of both astronomical and cosmological sources, both can be anisotropic. Numerically depicting these anisotropies can be critical in revealing the underlying properties of their origins. For the first time, we perform a theoretical analysis of the constraining ability of TianQin on multiple moments of the stochastic background. First, we find that with a one-year operation, for a background with a signal-to-noise ratio of 16, TianQin can recover the multiple moments up to $l=4$. We also identified a unique feature of the stochastic background sky map, which is the mirror symmetry along the fixed orbital plane of TianQin. Thirdly, we explain the difference in anisotropy recovering ability between TianQin and LISA, by employing the criteria of the singularity of the covariance matrix (which is the condition number). Finally, we find that since the different data channel combinations correspond to different singularities, certain combinations might have an advantage in stochastic background map-making. We believe that the findings of this work can provide an important reference to future stochastic background analysis pipelines. It can also serve as a guideline for designing better gravitational-wave detectors aiming to decipher anisotropies in the stochastic background.
在毫赫兹频段，随机引力波背景可以由天文源和宇宙源组成，两者都可以是各向异性的。数值描述这些各向异性对于揭示其起源的基本特性至关重要。我们首次对天琴对随机背景多矩的约束能力进行了理论分析。首先，我们发现在信噪比为16的背景下，天琴可以恢复高达$l=4$的多个矩。我们还发现了随机背景天图的一个独特特征，即沿天琴固定轨道平面的镜面对称性。第三，我们利用协方差矩阵的奇异性标准（即条件数）解释了天琴和 LISA 在各向异性恢复能力上的差异。最后，我们发现由于不同的数据通道组合对应不同的奇异性，因此某些组合在随机背景图制作中可能具有优势。我们相信，这项工作的发现可以为未来的随机背景分析管道提供重要参考。它还可以为设计更好的引力波探测器提供指导，以破译随机背景中的各向异性。
{"title":"Mapping Anisotropies in the Stochastic Gravitational-Wave Background with TianQin","authors":"Zhi-Yuan Li, Zheng-Cheng Liang, En-Kun Li, Jian-dong Zhang, Yi-Ming Hu","doi":"arxiv-2409.11245","DOIUrl":"https://doi.org/arxiv-2409.11245","url":null,"abstract":"In the milli-Hertz frequency band, stochastic gravitational-wave background\u0000can be composed of both astronomical and cosmological sources, both can be\u0000anisotropic. Numerically depicting these anisotropies can be critical in\u0000revealing the underlying properties of their origins. For the first time, we\u0000perform a theoretical analysis of the constraining ability of TianQin on\u0000multiple moments of the stochastic background. First, we find that with a\u0000one-year operation, for a background with a signal-to-noise ratio of 16,\u0000TianQin can recover the multiple moments up to $l=4$. We also identified a\u0000unique feature of the stochastic background sky map, which is the mirror\u0000symmetry along the fixed orbital plane of TianQin. Thirdly, we explain the\u0000difference in anisotropy recovering ability between TianQin and LISA, by\u0000employing the criteria of the singularity of the covariance matrix (which is\u0000the condition number). Finally, we find that since the different data channel\u0000combinations correspond to different singularities, certain combinations might\u0000have an advantage in stochastic background map-making. We believe that the\u0000findings of this work can provide an important reference to future stochastic\u0000background analysis pipelines. It can also serve as a guideline for designing\u0000better gravitational-wave detectors aiming to decipher anisotropies in the\u0000stochastic background.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this article, we extend the standard $Lambda$CDM model by incorporating causal viscous dark matter (vDM) modelled using Maxwell-Cattaneo theory and obtain a novel Hubble parameter solution for the model, which can even be extended to incorporate both radiation and baryonic matter components. A detailed and comprehensive analysis of the model is carried out by deriving theoretical constraints on model parameters, comparing the model with the latest observational data sets and validating the behaviour of the model under different thermodynamic laws. Such an in-depth analysis of the model yielded several intriguing results, like the presence of sign-switching bulk viscous pressure which aids both, the decelerated expansion in the early universe and the accelerated expansion in the late universe, possibility of having negative specific entropy rate in the early Universe while still satisfying the covariant second law of thermodynamics, and a correlation between relaxation time parameter and sign-switching redshift. Finally, we propose a unified dark matter (UDM) interpretation for the dark sector in this model and hence showed that, under the said UDM interpretation, this model can satisfy the much-required near equilibrium condition associated with the background dissipative theory both in the early and late phase of the Universe. Based on the NEC trend showcased by the model, we conjuncture that the late-accelerating behaviour of Universe can be viewed as a means for the UDM fluid to attain a global equilibrium state.
{"title":"$Λ$CDM Model Extension with Dissipative Dynamics and Sign-Switching Bulk Viscous Pressure","authors":"Vishnu A Pai, Sarath N, Titus K Mathew","doi":"arxiv-2409.10919","DOIUrl":"https://doi.org/arxiv-2409.10919","url":null,"abstract":"In this article, we extend the standard $Lambda$CDM model by incorporating\u0000causal viscous dark matter (vDM) modelled using Maxwell-Cattaneo theory and\u0000obtain a novel Hubble parameter solution for the model, which can even be\u0000extended to incorporate both radiation and baryonic matter components. A\u0000detailed and comprehensive analysis of the model is carried out by deriving\u0000theoretical constraints on model parameters, comparing the model with the\u0000latest observational data sets and validating the behaviour of the model under\u0000different thermodynamic laws. Such an in-depth analysis of the model yielded\u0000several intriguing results, like the presence of sign-switching bulk viscous\u0000pressure which aids both, the decelerated expansion in the early universe and\u0000the accelerated expansion in the late universe, possibility of having negative\u0000specific entropy rate in the early Universe while still satisfying the\u0000covariant second law of thermodynamics, and a correlation between relaxation\u0000time parameter and sign-switching redshift. Finally, we propose a unified dark\u0000matter (UDM) interpretation for the dark sector in this model and hence showed\u0000that, under the said UDM interpretation, this model can satisfy the\u0000much-required near equilibrium condition associated with the background\u0000dissipative theory both in the early and late phase of the Universe. Based on\u0000the NEC trend showcased by the model, we conjuncture that the late-accelerating\u0000behaviour of Universe can be viewed as a means for the UDM fluid to attain a\u0000global equilibrium state.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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