Nils Frederik Hasselmann, Beata Kunicka, Dirk Papendorf, Harald Kögel, Ulrich Johann, Dennis Weise and Alexander Sell
{"title":"Siderostat pointing: validation of an advanced line-of-sight pointing concept beyond LISA","authors":"Nils Frederik Hasselmann, Beata Kunicka, Dirk Papendorf, Harald Kögel, Ulrich Johann, Dennis Weise and Alexander Sell","doi":"10.1088/1361-6382/ade046","DOIUrl":"https://doi.org/10.1088/1361-6382/ade046","url":null,"abstract":"We present a mechanism prototype for a previously proposed advanced pointing concept for a Laser Interferometer Space Antenna-like space-based gravitational wave observatory that enables an architecture with two bi-directional interferometric laser links per S/C referenced to a single active test mass. Compared to the baseline concept, this eliminates an optical backlink connecting two individual optical benches and a massive flexing harness, significantly reducing the drag-free control’s complexity and avoiding self-gravity effects due to large moving parts. An experimental validation of the pointing jitter and creep of the pointing mechanism is performed. The general design procedure can also find application in lithography or other scenarios requiring ultra-stable manipulation of one or more opto-mechanical degrees of freedom.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"26 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144311796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Adamu Issifu, Franciele M da Silva, Luis C N Santos, Débora P Menezes and Tobias Frederico
{"title":"Strongly interacting quark matter in massive quark stars","authors":"Adamu Issifu, Franciele M da Silva, Luis C N Santos, Débora P Menezes and Tobias Frederico","doi":"10.1088/1361-6382/ade192","DOIUrl":"https://doi.org/10.1088/1361-6382/ade192","url":null,"abstract":"This paper investigates the properties of strongly coupled matter at high baryon densities (ρB) in quark stars (QSs). The QS model is based on the density-dependent quark mass (DDQM) framework, modified DDQM (MDDQM) by enhancing the single-gluon interaction to generate higher repulsive pressure. The model parameters are constrained using Bayesian inference, incorporating observational data from the pulsars HESS J1731 347, PSR J0030 0451, PSR J0740 6620, and PSR J0952 0607. Our results show that the MDDQM model produces QSs with higher mass and compactness compared to the DDQM model. Among the four MDDQM parameterizations studied, two yield maximum star masses of 1.86 and 2.10 and exhibit near-conformal behavior in the underlying quark matter (QM). The other two parameterizations, yielding QS masses of 2.30 and 2.37 , correspond to a stronger interaction in the underlying QM. These findings provide important insights into the equation of state of deconfined QM and its implications for the structure and stability of QSs.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144304585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Chaitra Chooda Chalavadi, G N Lathakumari and V Venkatesha
{"title":"A study of dark matter interactions with wormhole metrics in the context of f(Q) gravity","authors":"Chaitra Chooda Chalavadi, G N Lathakumari and V Venkatesha","doi":"10.1088/1361-6382/ade194","DOIUrl":"https://doi.org/10.1088/1361-6382/ade194","url":null,"abstract":"This study explores the impact of dark matter within the f(Q) gravity framework, emphasizing its role in supporting traversable wormhole solutions. By considering anisotropic matter sources modeled through Bose–Einstein condensate and Einasto density profiles, we derive a novel class of wormhole solutions. The shape function of the wormholes is constructed using the density profile equation and modified field equations, providing a robust foundation for these solutions. The analysis includes the incorporation of a traceless fluid equation of state, which reveals the intricate influence of dark matter on the existence and stability of wormhole structures. To ensure physical plausibility, specific parameter choices are made, confirming that the proposed solutions meet all essential conditions for traversable wormholes. Furthermore, energy conditions are systematically evaluated under four distinct scenarios, and embedding techniques are applied to gain deeper insights into the wormhole geometries. Next, we extend our study to analyze the volume integral quantifier and the anisotropic effect. This work provides a comprehensive perspective on the interplay between dark matter and f(Q) gravity, shedding light on the feasibility of exotic spacetime configurations. Finally, the stability of the derived wormhole solutions is verified using the Tolman–Oppenheimer–Volkoff equation, demonstrating a balance of forces and the physical stability of the models.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"36 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144296017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Electrodynamics in curved spacetime: gravitationally-induced constitutive equations and the spacetime index of refraction","authors":"F Masghatian, M Esfandiar and M Nouri-Zonoz","doi":"10.1088/1361-6382/addcb1","DOIUrl":"https://doi.org/10.1088/1361-6382/addcb1","url":null,"abstract":"Previous studies on spacetime index of refraction are mostly restricted to the static spacetimes. In this study we fill this gap by introducing the refractive index for stationary spacetimes, employing three different approaches. These include applying Fermat’s principle, employing the classical definition of refractive index, and using gravitationally-induced constitutive equations. These calculations are carried out in both threading and slicing spacetime decomposition formalisms, and their equivalence is established. We discuss possible applications of the spacetime index of refraction, especially in the study of light trajectories and their characteristics in stationary spacetimes. More specifically we show that there is a gravitational analog of a toroidal moment, and discuss a possible gravitational analog of nonreciprocal refraction in materials with a toroidal domain wall.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"41 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144268847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Killing and homothetic initial data for general hypersurfaces","authors":"Marc Mars and Gabriel Sánchez-Pérez","doi":"10.1088/1361-6382/addea3","DOIUrl":"https://doi.org/10.1088/1361-6382/addea3","url":null,"abstract":"In this paper we present a collection of general identities relating the deformation tensor of an arbitrary vector field η with the tensor on an abstract hypersurface of any causal character. As an application we establish necessary conditions on for the existence of a homothetic Killing vector on the spacetime where is embedded. The sufficiency of these conditions is then analysed in three specific settings. For spacelike hypersurfaces, we recover the well-known homothetic KID equations in the language of hypersurface data. For two intersecting null hypersurfaces, we generalize a previous result by Chruściel and Paetz, valid for Killings, to the homothetic case and, moreover, demonstrate that the equations can be formulated solely in terms of the initial data for the characteristic Cauchy problem, i.e. without involving a priori spacetime quantities. This puts the characteristic KID problem on equal footing with the spacelike KID problem. Furthermore, we highlight the versatility of the formalism by addressing the homothetic KID problem for smooth spacelike-characteristic initial data. Other initial value problems, such as the spacelike-characteristic with corners, can be approached similarly.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"36 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144260536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Ultra-massive spacetimes in 2 + 1 ...","authors":"Ingemar Bengtsson and José M M Senovilla","doi":"10.1088/1361-6382/addc2e","DOIUrl":"https://doi.org/10.1088/1361-6382/addc2e","url":null,"abstract":"We show that ultra-massive spacetimes exist also in dimensions with a positive cosmological constant . They can be created through the collapse of a spherical null dust shell. The exterior of the shell is then a Mess spacetime, that is to say a locally de Sitter spacetime that cannot be obtained as a quotient of de Sitter space.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"30 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144229073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Achieving non-orbital particle trapping in binary black holes through dynamic stability","authors":"A Kurmus, M Zajaček, G Kestin and L Deslauriers","doi":"10.1088/1361-6382/addc2f","DOIUrl":"https://doi.org/10.1088/1361-6382/addc2f","url":null,"abstract":"We present an interdisciplinary comparison between binary black hole systems and radio frequency Paul Traps, modeling the gravitational binary system as a rotating saddle near its center. This analogy connects these seemingly unrelated systems through the concept of dynamic stability. The rotating saddle potential is analytically tractable, allowing us to prove the existence of bounded charged particle trajectories under certain conditions. By focusing on stellar-mass black holes with a weak electric charge-a feature consistent with specific astrophysical conditions that leaves the spacetime metric largely unaffected but can influence nearby particle interactions-we can neglect complicating factors such as magnetic fields from large accretion disks of heavier black holes or stellar winds. Our simulation results demonstrate that charged particles can exhibit stable, non-orbital trajectories near the center of a binary system with charged stellar-mass black holes, providing unique three-dimensional trapping primarily through gravity. This system is distinctive in the literature for its non-orbital trapping mechanism. While theoretically intriguing, this trapping relies on specific conditions, including nearly identical black hole masses. These types of non-orbital trapping mechanisms could potentially allow for longer-lived plasma configurations, enhancing our ability to detect electromagnetic signatures from these systems. The significance of this work lies in the novel comparison between a laboratory-scale quantum system and a larger astrophysical one, opening new avenues for exploring parallels between microscopic and cosmic phenomena across fourteen orders of magnitude in distance.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"11 1","pages":"115017"},"PeriodicalIF":3.5,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Keefe Mitman, Leo C Stein, Michael Boyle, Nils Deppe, Lawrence E Kidder, Harald P Pfeiffer and Mark A Scheel
{"title":"Length dependence of waveform mismatch: a caveat on waveform accuracy","authors":"Keefe Mitman, Leo C Stein, Michael Boyle, Nils Deppe, Lawrence E Kidder, Harald P Pfeiffer and Mark A Scheel","doi":"10.1088/1361-6382/add8d9","DOIUrl":"https://doi.org/10.1088/1361-6382/add8d9","url":null,"abstract":"The Simulating eXtreme Spacetimes Collaboration’s code SpEC can now routinely simulate binary black hole mergers undergoing orbits, with the longest simulations undergoing nearly orbits. While this sounds impressive, the mismatch between the highest resolutions for this long simulation is . Meanwhile, the mismatch between resolutions for the more typical simulations tends to be , despite the resolutions being similar to the long simulations’. In this note, we explain why mismatch alone gives an incomplete picture of code—and waveform—quality, especially in the context of providing waveform templates for LISA and 3G detectors, which require templates with orbits. We argue that to ready the GW community for the sensitivity of future detectors, numerical relativity groups must be aware of this caveat, and also run future simulations with at least three resolutions to properly assess waveform accuracy.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"8 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144211316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Raissa Costa Barroso, Yves Lemière, François Mauger and Quentin Baghi
{"title":"Coronagraphic time-delay interferometry: characterization and updated geometric properties","authors":"Raissa Costa Barroso, Yves Lemière, François Mauger and Quentin Baghi","doi":"10.1088/1361-6382/addbbd","DOIUrl":"https://doi.org/10.1088/1361-6382/addbbd","url":null,"abstract":"The Laser Interferometer Space Antenna (LISA) will be a space-borne gravitational wave (GW) detector to be launched in the next decade. Central to LISA data analysis is time-delay interferometry (TDI), a numerical procedure which drastically reduces otherwise overwhelming laser frequency noise. LISA data analysis is usually performed on sets of TDI variables, e.g. Michelson variables or quasiorthogonal variables . We investigate a less standard TDI variable denoted κ which depends on time, or frequency, and two parameters . This so-called coronagraphic TDI variable has the singular property of canceling GW signal when tend to the sky position of the GW source. Note that, as a consequence of LISA’s planar symmetry, GW signal is also canceled when tend to . Nonetheless, thanks to this property, coronagraphic TDI has the potential to be an efficient model-agnostic method for sky localization of GW sources with LISA. These characteristics make it relevant for low-latency searches and a possible glitch veto. Although briefly discussed in the literature, coronagraphic TDI has only been tested on theoretical grounds. In this paper we validate the applicability of κ to sky localization of typical LISA sources, namely Galactic binaries and massive black hole binaries, when considering a simplified LISA instrument. The goal of this paper is to pave the way for applications of coronagraphic TDI to practical LISA data analysis problems.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"247 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144211347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Lars Fischer, Bianca Giaccone, Ivan Gonin, Anna Grassellino, Wolfgang Hillert, Timergali Khabiboulline, Tom Krokotsch, Gudrid Moortgat-Pick, Andrea Muhs, Yuriy Orlov, Michel Paulsen, Krisztian Peters, Sam Posen, Oleg Pronitchev and Marc Wenskat
{"title":"First characterisation of the MAGO cavity, a superconducting RF detector for kHz–MHz gravitational waves","authors":"Lars Fischer, Bianca Giaccone, Ivan Gonin, Anna Grassellino, Wolfgang Hillert, Timergali Khabiboulline, Tom Krokotsch, Gudrid Moortgat-Pick, Andrea Muhs, Yuriy Orlov, Michel Paulsen, Krisztian Peters, Sam Posen, Oleg Pronitchev and Marc Wenskat","doi":"10.1088/1361-6382/add8da","DOIUrl":"https://doi.org/10.1088/1361-6382/add8da","url":null,"abstract":"Heterodyne detection using microwave cavities is a promising method for detecting high-frequency gravitational waves (GWs) or ultralight axion dark matter. In this work, we report on studies conducted on a spherical 2-cell cavity developed by the MAGO collaboration for high-frequency GWs detection. Although fabricated around 20 years ago, the cavity had not been used since. Due to deviations from the nominal geometry, we conducted a mechanical survey and performed room-temperature plastic tuning. Measurements and simulations of the mechanical resonances and electromagnetic properties were carried out, as these are critical for estimating the cavity’s GW coupling potential. Based on these results, we plan further studies in a cryogenic environment. The cavity characterisation does not only provide valuable experience for a planned physics run but also informs the future development of improved cavity designs.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"146 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}