Pub Date : 2025-12-30DOI: 10.1016/j.dark.2025.102208
Wasif Husain
In this study, the impact of neutron decay into dark matter and various dark matter self-interaction strengths on neutron star properties have been explored. Using the quark-meson coupling (QMC) model for nucleon-only equations of state (EoSs), the effects of different matter compositions have been compared, including strange matter and self-interacting dark matter. The results demonstrate that increasing DM-DM self-repulsion stiffens the EoS, influencing the mass-radius relationship and stability of neutron stars. Furthermore, fundamental mode (f-mode) oscillations have been analyzed, which serve as a diagnostic tool for probing neutron star interiors. The f-mode frequencies follow universal relations, reinforcing their applicability for constraining dense matter properties. It has been shown that neutron stars composed of nucleons-only and self-interacting dark matter exhibit a universal behavior in damping time and angular frequency, whereas strange matter and non-self-interacting dark matter deviate from this trend. Importantly, it has been shown that for a GW energy release of E ∼ 1052 erg and a source distance of 25 Mpc, the characteristic strain and signal-to-noise ratio exceed the ET-D sensitivity threshold below ∼ 2.1 kHz for all models except the non-interacting DM case, demonstrating that neutron-to-dark matter decay scenarios, including the role of DM self-interactions, can be tested through next-generation gravitational-wave asteroseismology, offering a new probe of DM physics and the neutron lifetime anomaly.
{"title":"F-mode oscillations of neutron stars with dark matter from neutron decay: Implications for gravitational-wave detectability","authors":"Wasif Husain","doi":"10.1016/j.dark.2025.102208","DOIUrl":"10.1016/j.dark.2025.102208","url":null,"abstract":"<div><div>In this study, the impact of neutron decay into dark matter and various dark matter self-interaction strengths on neutron star properties have been explored. Using the quark-meson coupling (QMC) model for nucleon-only equations of state (EoSs), the effects of different matter compositions have been compared, including strange matter and self-interacting dark matter. The results demonstrate that increasing DM-DM self-repulsion stiffens the EoS, influencing the mass-radius relationship and stability of neutron stars. Furthermore, fundamental mode (f-mode) oscillations have been analyzed, which serve as a diagnostic tool for probing neutron star interiors. The f-mode frequencies follow universal relations, reinforcing their applicability for constraining dense matter properties. It has been shown that neutron stars composed of nucleons-only and self-interacting dark matter exhibit a universal behavior in damping time and angular frequency, whereas strange matter and non-self-interacting dark matter deviate from this trend. Importantly, it has been shown that for a GW energy release of <em>E</em> ∼ 10<sup>52</sup> erg and a source distance of 25 Mpc, the characteristic strain and signal-to-noise ratio exceed the ET-D sensitivity threshold below ∼ 2.1 kHz for all models except the non-interacting DM case, demonstrating that neutron-to-dark matter decay scenarios, including the role of DM self-interactions, can be tested through next-generation gravitational-wave asteroseismology, offering a new probe of DM physics and the neutron lifetime anomaly.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102208"},"PeriodicalIF":6.4,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-30DOI: 10.1016/j.dark.2025.102210
Shan-Ping Wu , Yu-Xiao Liu , Shao-Wen Wei
The generalized free energy landscape plays a pivotal role in understanding black hole thermodynamics and phase transitions. In general relativity, one can directly derive the generalized free energy from the contributions of black holes exhibiting conical singularities. In this work, we extend this idea to general covariant theories. By employing Noether’s second theorem, we present an alternative formulation of the Lagrangian, which can elucidate the role of conical singularities. We demonstrate that, in general, the contribution from conical singularities depends on the specific implementation of the regularization scheme and is not uniquely determined; this feature is explicitly exhibited and confirmed in three-dimensional new massive gravity. Nevertheless, these ambiguities can be absorbed into the second-order (and higher) corrections induced by conical singularities when the gravitational theory is described by the Lagrangian L(gab, Rabcd). Moreover, for certain theories such as general relativity and Bumblebee gravity, this contribution simplifies to a well-defined result. However, the interpretation of the generalized free energy in Bumblebee gravity is somewhat different, with its extrema corresponding to the geometry of conical singularities. Our results uncover the particular properties of the generalized free energy beyond general relativity.
{"title":"Generalized free energy landscapes from Iyer-Wald formalism","authors":"Shan-Ping Wu , Yu-Xiao Liu , Shao-Wen Wei","doi":"10.1016/j.dark.2025.102210","DOIUrl":"10.1016/j.dark.2025.102210","url":null,"abstract":"<div><div>The generalized free energy landscape plays a pivotal role in understanding black hole thermodynamics and phase transitions. In general relativity, one can directly derive the generalized free energy from the contributions of black holes exhibiting conical singularities. In this work, we extend this idea to general covariant theories. By employing Noether’s second theorem, we present an alternative formulation of the Lagrangian, which can elucidate the role of conical singularities. We demonstrate that, in general, the contribution from conical singularities depends on the specific implementation of the regularization scheme and is not uniquely determined; this feature is explicitly exhibited and confirmed in three-dimensional new massive gravity. Nevertheless, these ambiguities can be absorbed into the second-order (and higher) corrections induced by conical singularities when the gravitational theory is described by the Lagrangian <em>L</em>(<em>g<sub>ab</sub>, R<sub>abcd</sub></em>). Moreover, for certain theories such as general relativity and Bumblebee gravity, this contribution simplifies to a well-defined result. However, the interpretation of the generalized free energy in Bumblebee gravity is somewhat different, with its extrema corresponding to the geometry of conical singularities. Our results uncover the particular properties of the generalized free energy beyond general relativity.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102210"},"PeriodicalIF":6.4,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-29DOI: 10.1016/j.dark.2025.102206
Ahmad Al-Badawi , Faizuddin Ahmed , Orhan Dönmez , Fatih Doğan , Behnam Pourhassan , i̇zzet Sakallı , Yassine Sekhmani
This investigation examines quasi-periodic oscillations (QPOs) in two quantum-corrected black hole (BH) spacetimes that preserve general covariance while incorporating quantum gravitational effects through a dimensionless parameter ζ. We combine analytical derivations of epicyclic frequencies with comprehensive numerical simulations of Bondi-Hoyle-Lyttleton (BHL) accretion to explore how quantum corrections manifest in observable astrophysical phenomena. Using a fiducial BH mass of representative of stellar-mass X-ray binaries, we demonstrate that the two models exhibit fundamentally different behaviors: Model-I modifies both temporal and radial metric components, leading to innermost stable circular orbit migration proportional to ζ4 and dramatic stagnation point evolution from 27M to 5M as quantum corrections strengthen. Model-II preserves the classical temporal component while altering only spatial geometry, maintaining constant stagnation points and stable cavity structures throughout the parameter range. Our numerical simulations reveal distinct QPO generation mechanisms, with Model-I showing systematic frequency evolution and cavity shrinkage that suppresses oscillations for ζ ≥ 3M, while Model-II maintains stable low-frequency modes up to ζ ≥ 5M. Power spectral density analyzes demonstrate characteristic frequency ratios (3: 2, 2: 1, 5: 3) consistent with observations from X-ray binaries, providing specific targets for discriminating between quantum correction scenarios. The hydrodynamically derived constraints (ζ ≲ 4M) show remarkable agreement with independent Event Horizon Telescope limits for M87* and Sgr A*, validating our theoretical framework through multiple observational channels. These results establish QPO frequency analysis as a probe for detecting quantum gravitational effects in astrophysical BHs and demonstrate the complementary nature of timing and imaging observations in constraining fundamental physics.
{"title":"Analytic and numerical constraints on QPOs in EHT and XRB sources using quantum-corrected black holes","authors":"Ahmad Al-Badawi , Faizuddin Ahmed , Orhan Dönmez , Fatih Doğan , Behnam Pourhassan , i̇zzet Sakallı , Yassine Sekhmani","doi":"10.1016/j.dark.2025.102206","DOIUrl":"10.1016/j.dark.2025.102206","url":null,"abstract":"<div><div>This investigation examines quasi-periodic oscillations (QPOs) in two quantum-corrected black hole (BH) spacetimes that preserve general covariance while incorporating quantum gravitational effects through a dimensionless parameter <em>ζ</em>. We combine analytical derivations of epicyclic frequencies with comprehensive numerical simulations of Bondi-Hoyle-Lyttleton (BHL) accretion to explore how quantum corrections manifest in observable astrophysical phenomena. Using a fiducial BH mass of <span><math><mrow><mi>M</mi><mo>=</mo><mn>10</mn><msub><mi>M</mi><mo>⊙</mo></msub></mrow></math></span> representative of stellar-mass X-ray binaries, we demonstrate that the two models exhibit fundamentally different behaviors: Model-I modifies both temporal and radial metric components, leading to innermost stable circular orbit migration proportional to <em>ζ</em><sup>4</sup> and dramatic stagnation point evolution from 27<em>M</em> to 5<em>M</em> as quantum corrections strengthen. Model-II preserves the classical temporal component while altering only spatial geometry, maintaining constant stagnation points and stable cavity structures throughout the parameter range. Our numerical simulations reveal distinct QPO generation mechanisms, with Model-I showing systematic frequency evolution and cavity shrinkage that suppresses oscillations for <em>ζ</em> ≥ 3<em>M</em>, while Model-II maintains stable low-frequency modes up to <em>ζ</em> ≥ 5<em>M</em>. Power spectral density analyzes demonstrate characteristic frequency ratios (3: 2, 2: 1, 5: 3) consistent with observations from X-ray binaries, providing specific targets for discriminating between quantum correction scenarios. The hydrodynamically derived constraints (<em>ζ</em> ≲ 4<em>M</em>) show remarkable agreement with independent Event Horizon Telescope limits for M87* and Sgr A*, validating our theoretical framework through multiple observational channels. These results establish QPO frequency analysis as a probe for detecting quantum gravitational effects in astrophysical BHs and demonstrate the complementary nature of timing and imaging observations in constraining fundamental physics.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102206"},"PeriodicalIF":6.4,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-25DOI: 10.1016/j.dark.2025.102201
Cemsinan Deliduman , Furkan Şakir Dilsiz , Selinay Sude Binici
To better distinguish the nature of H0 and S8 tensions, it is necessary to separate the effects of expansion and the growth of structure. The growth index γ was identified as the most important parameter that characterizes the growth of density fluctuations independently of the effects of cosmic expansion. In the ΛCDM model, analyses performed with various cosmological datasets indicate that the growth index has to be larger than its theoretically predicted value. Cosmological models based on f(R) gravity theories have scale-dependent growth indices, whose values are even more at odds with the growth rate data. In this work, we evaluate the growth index in the γδCDM model both theoretically and numerically. Although based on f(R) gravity theory, we show through several analyses with different combinations of datasets that the growth index in the γδCDM model is very close in value to the ΛCDM and the ωCDM models. The growth of structure is suppressed in the γδCDM model, which is formulated with the extended gravitational growth framework. Upon analyzing cosmological data, we ascertain that the γδCDM model is equally competitive as the ΛCDM and the ωCDM models.
{"title":"Growth index in the γδCDM model","authors":"Cemsinan Deliduman , Furkan Şakir Dilsiz , Selinay Sude Binici","doi":"10.1016/j.dark.2025.102201","DOIUrl":"10.1016/j.dark.2025.102201","url":null,"abstract":"<div><div>To better distinguish the nature of <em>H</em><sub>0</sub> and <em>S</em><sub>8</sub> tensions, it is necessary to separate the effects of expansion and the growth of structure. The growth index <em>γ</em> was identified as the most important parameter that characterizes the growth of density fluctuations independently of the effects of cosmic expansion. In the ΛCDM model, analyses performed with various cosmological datasets indicate that the growth index has to be larger than its theoretically predicted value. Cosmological models based on <em>f</em>(<em>R</em>) gravity theories have scale-dependent growth indices, whose values are even more at odds with the growth rate data. In this work, we evaluate the growth index in the <em>γδ</em>CDM model both theoretically and numerically. Although based on <em>f</em>(<em>R</em>) gravity theory, we show through several analyses with different combinations of datasets that the growth index in the <em>γδ</em>CDM model is very close in value to the ΛCDM and the <em>ω</em>CDM models. The growth of structure is suppressed in the <em>γδ</em>CDM model, which is formulated with the extended gravitational growth framework. Upon analyzing cosmological data, we ascertain that the <em>γδ</em>CDM model is equally competitive as the ΛCDM and the <em>ω</em>CDM models.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102201"},"PeriodicalIF":6.4,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
The modeling of astrophysical compact objects has recently attracted significant interest of the research community to understand their stable internal structures. In particular, the addition of dark energy as another source of matter configuration in the interiors of such stars has elevated the focus on their theoretical development. In this study, we present a ne model of static, spherically symmetric, and anisotropic compact stars within the framework of f(R) modified theories. The stellar structure is described by a two-fluid system consisting of ordinary matter and dark energy. We develop the analytical solutions to the governing modified field equations using the well-known Finch-Skea ansatz for the metric potentials, coupled with a linear equation of state for the dark energy component. The model parameters, including the metric ansatz, are determined via smooth matching conditions at the boundary between the interior and exterior spacetime regions. To demonstrate the physical viability of the model, we apply our formulation to the compact star 4U 1538-52, utilizing the stable and widely studied gravity model. We analyze an extensive investigation of the physical features, including the behavior of metric equations, matter variables, energy conditions, and stability criteria. In addition, we evaluate the evolution of the mass function, surface redshift, and compactness factor of the considered compact star candidates. The results confirm the stability, feasibility, and physical impact of the constructed solutions along with presenting additional insight into the interplay between dark energy structures and modified gravity within astrophysical circumstances. Graphical representations of key parameters enhance the clarity of our findings. The results demonstrate that our model is physically acceptable and stable in f(R) gravity.
{"title":"Interior structure and physical features of dark energy relativistic stars in power law gravity model","authors":"M.R. Shahzad , Wajiha Habib , Asifa Ashraf , Muneerah Alomar , Awatef Abidi , Maryam Al Huwayz","doi":"10.1016/j.dark.2025.102198","DOIUrl":"10.1016/j.dark.2025.102198","url":null,"abstract":"<div><div>The modeling of astrophysical compact objects has recently attracted significant interest of the research community to understand their stable internal structures. In particular, the addition of dark energy as another source of matter configuration in the interiors of such stars has elevated the focus on their theoretical development. In this study, we present a ne model of static, spherically symmetric, and anisotropic compact stars within the framework of <em>f</em>(<em>R</em>) modified theories. The stellar structure is described by a two-fluid system consisting of ordinary matter and dark energy. We develop the analytical solutions to the governing modified field equations using the well-known Finch-Skea ansatz for the metric potentials, coupled with a linear equation of state for the dark energy component. The model parameters, including the metric ansatz, are determined via smooth matching conditions at the boundary between the interior and exterior spacetime regions. To demonstrate the physical viability of the model, we apply our formulation to the compact star 4U 1538-52, utilizing the stable and widely studied <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow><mo>=</mo><mi>R</mi><mo>+</mo><mn>2</mn><mi>χ</mi><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span> gravity model. We analyze an extensive investigation of the physical features, including the behavior of metric equations, matter variables, energy conditions, and stability criteria. In addition, we evaluate the evolution of the mass function, surface redshift, and compactness factor of the considered compact star candidates. The results confirm the stability, feasibility, and physical impact of the constructed solutions along with presenting additional insight into the interplay between dark energy structures and modified gravity within astrophysical circumstances. Graphical representations of key parameters enhance the clarity of our findings. The results demonstrate that our model is physically acceptable and stable in <em>f</em>(<em>R</em>) gravity.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102198"},"PeriodicalIF":6.4,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-24DOI: 10.1016/j.dark.2025.102202
Erdem Sucu, İzzet Sakallı
We investigate quantum corrections to the thermodynamics of charged, rotating BTZ black holes in AdS spacetime using both Generalized Uncertainty Principle (GUP) and exponential entropy corrections. The Hamilton–Jacobi tunneling method yields the Hawking temperature and its GUP-modified form, revealing how Planck-scale effects suppress thermal radiation. Exponential corrections to the Bekenstein-Hawking entropy lead to modified expressions for internal energy, Helmholtz and Gibbs free energies, pressure, enthalpy, and heat capacity. The AdS radius ℓ emerges as a critical parameter: smaller values enhance gravitational confinement and thermodynamic stability, while larger values weaken these effects. The heat capacity remains positive across parameter space, ruling out second-order phase transitions. However, the JT coefficient exhibits remarkable oscillatory behavior near rh ≈ 1.05, alternating between heating and cooling phases during isenthalpic expansion. These oscillations intensify with increasing ℓ, indicating reduced stability in weakly curved AdS backgrounds. Gravitational redshift calculations in the weak-field limit show that the logarithmic charge coupling produces unbounded growth at large distances, with strong ℓ-dependence providing observational signatures. Our results demonstrate that (2+1)-dimensional black holes possess richer thermodynamic structure than their higher-dimensional counterparts, with quantum corrections introducing novel critical phenomena while preserving overall stability. These findings connect microscopic quantum gravity effects to macroscopic thermodynamic behavior, offering new perspectives on black hole physics in lower dimensions.
{"title":"Quantum corrections and exotic criticality in charged rotating BTZ black holes","authors":"Erdem Sucu, İzzet Sakallı","doi":"10.1016/j.dark.2025.102202","DOIUrl":"10.1016/j.dark.2025.102202","url":null,"abstract":"<div><div>We investigate quantum corrections to the thermodynamics of charged, rotating BTZ black holes in AdS spacetime using both Generalized Uncertainty Principle (GUP) and exponential entropy corrections. The Hamilton–Jacobi tunneling method yields the Hawking temperature and its GUP-modified form, revealing how Planck-scale effects suppress thermal radiation. Exponential corrections to the Bekenstein-Hawking entropy lead to modified expressions for internal energy, Helmholtz and Gibbs free energies, pressure, enthalpy, and heat capacity. The AdS radius ℓ emerges as a critical parameter: smaller values enhance gravitational confinement and thermodynamic stability, while larger values weaken these effects. The heat capacity remains positive across parameter space, ruling out second-order phase transitions. However, the JT coefficient exhibits remarkable oscillatory behavior near <em>r<sub>h</sub></em> ≈ 1.05, alternating between heating and cooling phases during isenthalpic expansion. These oscillations intensify with increasing ℓ, indicating reduced stability in weakly curved AdS backgrounds. Gravitational redshift calculations in the weak-field limit show that the logarithmic charge coupling produces unbounded growth at large distances, with strong ℓ-dependence providing observational signatures. Our results demonstrate that (2+1)-dimensional black holes possess richer thermodynamic structure than their higher-dimensional counterparts, with quantum corrections introducing novel critical phenomena while preserving overall stability. These findings connect microscopic quantum gravity effects to macroscopic thermodynamic behavior, offering new perspectives on black hole physics in lower dimensions.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102202"},"PeriodicalIF":6.4,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we investigate the motion of test particles around a black hole (BH) characterized by spontaneous Lorentz symmetry breaking, parameterized by α. We begin by outlining the theoretical framework underlying such BH geometries and subsequently analyze the corresponding dynamics of massive test particles. By applying the effective potential, we determine the exact conditions for circular trajectories and analyze the properties of the innermost stable circular orbits (ISCOs) parameters. In addition, the effective force acting on particles is studied, which gives further insight into orbital stability. Also, we are testing the BH shadow with M87* and Sgr A* under the influence of BH parameters.. Furthermore, we explore oscillatory phenomena associated with small perturbations around circular orbits, calculating the frequencies as measured by both local and distant observers, as well as the periastron precession. In this context, these results shed light on possible observational signatures of Lorentz-symmetry breaking in strong gravitational regimes and contribute to the understanding of modified BH physics.
{"title":"Stability analysis and oscillatory behavior of orbits around Lorentz-violating black holes","authors":"Rana Muhammad Zulqarnain , Abdelmalek Bouzenada , Farruh Atamurotov , Ikhtiyor Saidov , A.S. Alqahtani , Phongpichit Channuie","doi":"10.1016/j.dark.2025.102200","DOIUrl":"10.1016/j.dark.2025.102200","url":null,"abstract":"<div><div>In this paper, we investigate the motion of test particles around a black hole (BH) characterized by spontaneous Lorentz symmetry breaking, parameterized by <em>α</em>. We begin by outlining the theoretical framework underlying such BH geometries and subsequently analyze the corresponding dynamics of massive test particles. By applying the effective potential, we determine the exact conditions for circular trajectories and analyze the properties of the innermost stable circular orbits (ISCOs) parameters. In addition, the effective force acting on particles is studied, which gives further insight into orbital stability. Also, we are testing the BH shadow with M87* and Sgr A* under the influence of BH parameters.. Furthermore, we explore oscillatory phenomena associated with small perturbations around circular orbits, calculating the frequencies as measured by both local and distant observers, as well as the periastron precession. In this context, these results shed light on possible observational signatures of Lorentz-symmetry breaking in strong gravitational regimes and contribute to the understanding of modified BH physics.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102200"},"PeriodicalIF":6.4,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-21DOI: 10.1016/j.dark.2025.102195
Oem Trivedi , Abraham Loeb
Primordial Black Holes (PBHs) represent one of the more interesting ways to address dark matter, at the interface of both cosmology and quantum gravity. It is no surprise then that testing PBHs is a venue of active interest, with several cosmological and astrophysical probes constraining different mass ranges. In this work, we propose novel Solar System scale searches for PBHs, motivated by the unique precision and coverage of local observables. We show that asteroid to dwarf planet mass PBHs can induce measurable dipolar timing signatures in pulsar timing arrays, while planetary mass PBHs can generate detectable ADAF accretion flares through interactions with Kuiper Belt bodies. Together, these complementary approaches open a new observational frontier for probing PBHs across mass ranges that remain unconstrained by conventional cosmological methods.
{"title":"Novel solar system probes for primordial black holes","authors":"Oem Trivedi , Abraham Loeb","doi":"10.1016/j.dark.2025.102195","DOIUrl":"10.1016/j.dark.2025.102195","url":null,"abstract":"<div><div>Primordial Black Holes (PBHs) represent one of the more interesting ways to address dark matter, at the interface of both cosmology and quantum gravity. It is no surprise then that testing PBHs is a venue of active interest, with several cosmological and astrophysical probes constraining different mass ranges. In this work, we propose novel Solar System scale searches for PBHs, motivated by the unique precision and coverage of local observables. We show that asteroid to dwarf planet mass PBHs can induce measurable dipolar timing signatures in pulsar timing arrays, while planetary mass PBHs can generate detectable ADAF accretion flares through interactions with Kuiper Belt bodies. Together, these complementary approaches open a new observational frontier for probing PBHs across mass ranges that remain unconstrained by conventional cosmological methods.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102195"},"PeriodicalIF":6.4,"publicationDate":"2025-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-20DOI: 10.1016/j.dark.2025.102192
Hyerim Noh , Jai-chan Hwang
We study a massive-photon electrodynamics and magnetohydrodynamics (MHD) in the curved spacetime of Einstein’s gravity. We consider a Proca-type photon mass and present equations in terms of electric and magnetic (EM) fields and the vector potential. We present the electrodynamics and MHD in the covariant and ADM formulations valid in general spacetime and in linearly perturbed cosmological spacetime. We present wave equations assuming the metric variations are negligible compared with the field variations. Equations are derived without fixing the temporal gauge condition and the gauge transformation properties of the EM fields and the vector potential are presented. Using the post-Newtonian approximation we show the dark Proca field behaves as dust in the non-relativistic limit under the Klein transformation.
{"title":"Massive-photon electrodynamics and MHD in curved spacetime and cosmology","authors":"Hyerim Noh , Jai-chan Hwang","doi":"10.1016/j.dark.2025.102192","DOIUrl":"10.1016/j.dark.2025.102192","url":null,"abstract":"<div><div>We study a massive-photon electrodynamics and magnetohydrodynamics (MHD) in the curved spacetime of Einstein’s gravity. We consider a Proca-type photon mass and present equations in terms of electric and magnetic (EM) fields and the vector potential. We present the electrodynamics and MHD in the covariant and ADM formulations valid in general spacetime and in linearly perturbed cosmological spacetime. We present wave equations assuming the metric variations are negligible compared with the field variations. Equations are derived without fixing the temporal gauge condition and the gauge transformation properties of the EM fields and the vector potential are presented. Using the post-Newtonian approximation we show the dark Proca field behaves as dust in the non-relativistic limit under the Klein transformation.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102192"},"PeriodicalIF":6.4,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
We investigate the thermodynamic extremality, topological charge structure, and thermodynamic curvature of non-Abelian dilaton black holes. The dilaton coupling significantly alters thermodynamic properties, enabling the verification of extremality conditions. By analyzing normalized thermodynamic vector fields, we classify topological charges through the identification of critical zero points, with their stability confirmed via winding number analysis. These topological sectors vary distinctly with the dilaton parameter. The free energy landscape is interpreted as a scalar field over parameter space, with its extrema corresponding to topological phases. This allows consistent charge assignments aligned with known solutions, such as the AdS Reissner-Nordström black hole. We further explore the topology of photon spheres and demonstrate their crucial role in black hole stability, establishing a strong link between thermodynamic topology and spacetime geometry. Finally, thermodynamic curvature is used to probe microscopic interactions, revealing predominantly attractive behavior with possible repulsive transitions near criticality. Our results indicate a rich phase structure and a non-trivial microstructure shaped by the interplay of dilaton and non-Abelian gauge fields.
{"title":"Thermodynamic signatures of non-Abelian dilaton black holes","authors":"Ankit Anand , Aditya Singh , Saeed Noori Gashti , Behnam Pourhassan","doi":"10.1016/j.dark.2025.102197","DOIUrl":"10.1016/j.dark.2025.102197","url":null,"abstract":"<div><div>We investigate the thermodynamic extremality, topological charge structure, and thermodynamic curvature of non-Abelian dilaton black holes. The dilaton coupling significantly alters thermodynamic properties, enabling the verification of extremality conditions. By analyzing normalized thermodynamic vector fields, we classify topological charges through the identification of critical zero points, with their stability confirmed via winding number analysis. These topological sectors vary distinctly with the dilaton parameter. The free energy landscape is interpreted as a scalar field over parameter space, with its extrema corresponding to topological phases. This allows consistent charge assignments aligned with known solutions, such as the AdS Reissner-Nordström black hole. We further explore the topology of photon spheres and demonstrate their crucial role in black hole stability, establishing a strong link between thermodynamic topology and spacetime geometry. Finally, thermodynamic curvature is used to probe microscopic interactions, revealing predominantly attractive behavior with possible repulsive transitions near criticality. Our results indicate a rich phase structure and a non-trivial microstructure shaped by the interplay of dilaton and non-Abelian gauge fields.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102197"},"PeriodicalIF":6.4,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}