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Analysis

This paper investigates the production of primordial black holes (PBHs) as a dark matter candidate within the framework of Horndeski gravity. It focuses on a specific scenario where the inflationary dynamics is controlled by a cubic Horndeski interaction, leading to an ultra-slow-roll phase. The key finding is that this mechanism can amplify the curvature power spectrum on small scales, potentially generating asteroid-mass PBHs that could account for a significant fraction of dark matter, while also predicting observable gravitational wave signatures. The work is significant because it provides a concrete mechanism for PBH formation within a well-motivated theoretical framework, addressing the dark matter problem and offering testable predictions.
Reference

The mechanism amplifies the curvature power spectrum on small scales without introducing any feature in the potential, leading to the formation of asteroid-mass PBHs.

Analysis

This paper explores the strong gravitational lensing and shadow properties of a black hole within the framework of bumblebee gravity, which incorporates a global monopole charge and Lorentz symmetry breaking. The study aims to identify observational signatures that could potentially validate or refute bumblebee gravity in the strong-field regime by analyzing how these parameters affect lensing observables and shadow morphology. This is significant because it provides a way to test alternative theories of gravity using astrophysical observations.
Reference

The results indicate that both the global monopole charge and Lorentz-violating parameters significantly influence the photon sphere, lensing observables, and shadow morphology, potentially providing observational signatures for testing bumblebee gravity in the strong-field regime.

Analysis

This paper addresses the ambiguity in the vacuum sector of effective quantum gravity models, which hinders phenomenological investigations. It proposes a constructive framework to formulate 4D covariant actions based on the system's degrees of freedom (dust and gravity) and two guiding principles. This framework leads to a unique and static vacuum solution, resolving the 'curvature polymerisation ambiguity' in loop quantum cosmology and unifying the description of black holes and cosmology.
Reference

The constructive framework produces a fully 4D-covariant action that belongs to the class of generalised extended mimetic gravity models.

Analysis

This paper explores the interior structure of black holes, specifically focusing on the oscillatory behavior of the Kasner exponent near the critical point of hairy black holes. The key contribution is the introduction of a nonlinear term (λ) that allows for precise control over the periodicity of these oscillations, providing a new way to understand and potentially manipulate the complex dynamics within black holes. This is relevant to understanding the holographic superfluid duality.
Reference

The nonlinear coefficient λ provides accurate control of this periodicity: a positive λ stretches the region, while a negative λ compresses it.

Analysis

This paper explores a novel construction in the context of AdS/CFT, specifically investigating the holographic duals of a specific type of entanglement in multiple copies of a gauge theory. The authors propose a connection between sums over gauge group representations in matrix models and 'bubbling wormhole' geometries, which are multi-covers of AdS5 x S5. The work contributes to our understanding of the relationship between entanglement, geometry, and gauge theory, potentially offering new insights into black hole physics and quantum gravity.
Reference

The holographic duals are ''bubbling wormhole'' geometries: multi-covers of AdS$_5$ $ imes S^5$ whose conformal boundary consists of multiple four-spheres intersecting on a common circle.

Analysis

This paper explores the connection between the holographic central charge, black hole thermodynamics, and quantum information using the AdS/CFT correspondence. It investigates how the size of the central charge (large vs. small) impacts black hole stability, entropy, and the information loss paradox. The study provides insights into the nature of gravity and the behavior of black holes in different quantum gravity regimes.
Reference

The paper finds that the entanglement entropy of Hawking radiation before the Page time increases with time, with the slope determined by the central charge. After the Page time, the unitarity of black hole evaporation is restored, and the entanglement entropy includes a logarithmic correction related to the central charge.

Analysis

The paper investigates the combined effects of non-linear electrodynamics (NED) and dark matter (DM) on a magnetically charged black hole (BH) within a Hernquist DM halo. The study focuses on how magnetic charge and halo parameters influence BH observables, particularly event horizon position, critical impact parameter, and strong gravitational lensing (GL) phenomena. A key finding is the potential for charge and halo parameters to nullify each other's effects, making the BH indistinguishable from a Schwarzschild BH in terms of certain observables. The paper also uses observational data from super-massive BHs (SMBHs) to constrain the model parameters.
Reference

The paper finds combinations of charge and halo parameters that leave the deflection angle unchanged from the Schwarzschild case, thereby leading to a situation where an MHDM BH and a Schwarzschild BH become indistinguishable.

Model-Independent Search for Gravitational Wave Echoes

Published:Dec 31, 2025 08:49
1 min read
ArXiv

Analysis

This paper presents a novel approach to search for gravitational wave echoes, which could reveal information about the near-horizon structure of black holes. The model-independent nature of the search is crucial because theoretical predictions for these echoes are uncertain. The authors develop a method that leverages a generalized phase-marginalized likelihood and optimized noise suppression techniques. They apply this method to data from the LIGO-Virgo-KAGRA (LVK) collaboration, specifically focusing on events with high signal-to-noise ratios. The lack of detection allows them to set upper limits on the strength of potential echoes, providing valuable constraints on theoretical models.
Reference

No statistically significant evidence for postmerger echoes is found.

Analysis

This paper explores the behavior of Proca stars (hypothetical compact objects) within a theoretical framework that includes an infinite series of corrections to Einstein's theory of gravity. The key finding is the emergence of 'frozen stars' – horizonless objects that avoid singularities and mimic extremal black holes – under specific conditions related to the coupling constant and the order of the curvature corrections. This is significant because it offers a potential alternative to black holes, addressing the singularity problem and providing a new perspective on compact objects.
Reference

Frozen stars contain neither curvature singularities nor event horizons. These frozen stars develop a critical horizon at a finite radius r_c, where -g_{tt} and 1/g_{rr} approach zero. The frozen star is indistinguishable from that of an extremal black hole outside r_c, and its compactness can reach the extremal black hole value.

Analysis

This paper develops a worldline action for a Kerr black hole, a complex object in general relativity, by matching to a tree-level Compton amplitude. The work focuses on infinite spin orders, which is a significant advancement. The authors acknowledge the need for loop corrections, highlighting the effective theory nature of their approach. The paper's contribution lies in providing a closed-form worldline action and analyzing the role of quadratic-in-Riemann operators, particularly in the same- and opposite-helicity sectors. This work is relevant to understanding black hole dynamics and quantum gravity.
Reference

The paper argues that in the same-helicity sector the $R^2$ operators have no intrinsic meaning, as they merely remove unwanted terms produced by the linear-in-Riemann operators.

Analysis

This paper investigates the dynamics of a charged scalar field near the horizon of an extremal charged BTZ black hole. It demonstrates that the electric field in the near-horizon AdS2 region can trigger an instability, which is resolved by the formation of a scalar cloud. This cloud screens the electric flux, leading to a self-consistent stationary configuration. The paper provides an analytical solution for the scalar profile and discusses its implications, offering insights into electric screening in black holes and the role of near-horizon dynamics.
Reference

The paper shows that the instability is resolved by the formation of a static scalar cloud supported by Schwinger pair production.

CNN for Velocity-Resolved Reverberation Mapping

Published:Dec 30, 2025 19:37
1 min read
ArXiv

Analysis

This paper introduces a novel application of Convolutional Neural Networks (CNNs) to deconvolve noisy and gapped reverberation mapping data, specifically for constructing velocity-delay maps in active galactic nuclei. This is significant because it offers a new computational approach to improve the analysis of astronomical data, potentially leading to a better understanding of the environment around supermassive black holes. The use of CNNs for this type of deconvolution problem is a promising development.
Reference

The paper showcases that such methods have great promise for the deconvolution of reverberation mapping data products.

Analysis

This paper addresses a fundamental question in quantum physics: can we detect entanglement when one part of an entangled system is hidden behind a black hole's event horizon? The surprising answer is yes, due to limitations on the localizability of quantum states. This challenges the intuitive notion that information loss behind the horizon makes the entangled and separable states indistinguishable. The paper's significance lies in its exploration of quantum information in extreme gravitational environments and its potential implications for understanding black hole information paradoxes.
Reference

The paper shows that fundamental limitations on the localizability of quantum states render the two scenarios, in principle, distinguishable.

Event Horizon Formation Time Bound in Black Hole Collapse

Published:Dec 30, 2025 19:00
1 min read
ArXiv

Analysis

This paper establishes a temporal bound on event horizon formation in black hole collapse, extending existing inequalities like the Penrose inequality. It demonstrates that the Schwarzschild exterior maximizes the formation time under specific conditions, providing a new constraint on black hole dynamics. This is significant because it provides a deeper understanding of black hole formation and evolution, potentially impacting our understanding of gravitational physics.
Reference

The Schwarzschild exterior maximizes the event horizon formation time $ΔT_{\text{eh}}=\frac{19}{6}m$ among all asymptotically flat, static, spherically-symmetric black holes with the same ADM mass $m$ that satisfy the weak energy condition.

Analysis

This paper derives effective equations for gravitational perturbations inside a black hole using hybrid loop quantum cosmology. It's significant because it provides a framework to study quantum corrections to the classical description of black hole interiors, potentially impacting our understanding of gravitational wave propagation in these extreme environments.
Reference

The resulting equations take the form of Regge-Wheeler equations modified by expectation values of the quantum black hole geometry, providing a clear characterization of quantum corrections to the classical description of the black hole interior.

Analysis

This paper addresses a practical problem in financial markets: how an agent can maximize utility while adhering to constraints based on pessimistic valuations (model-independent bounds). The use of pathwise constraints and the application of max-plus decomposition are novel approaches. The explicit solutions for complete markets and the Black-Scholes-Merton model provide valuable insights for practical portfolio optimization, especially when dealing with mispriced options.
Reference

The paper provides an expression of the optimal terminal wealth for complete markets using max-plus decomposition and derives explicit forms for the Black-Scholes-Merton model.

Analysis

This paper provides a comprehensive introduction to Gaussian bosonic systems, a crucial tool in quantum optics and continuous-variable quantum information, and applies it to the study of semi-classical black holes and analogue gravity. The emphasis on a unified, platform-independent framework makes it accessible and relevant to a broad audience. The application to black holes and analogue gravity highlights the practical implications of the theoretical concepts.
Reference

The paper emphasizes the simplicity and platform independence of the Gaussian (phase-space) framework.

Black Hole Images as Thermodynamic Probes

Published:Dec 30, 2025 12:15
1 min read
ArXiv

Analysis

This paper explores how black hole images can be used to understand the thermodynamic properties and evolution of black holes, specifically focusing on the Reissner-Nordström-AdS black hole. It demonstrates that these images encode information about phase transitions and the ensemble (isobaric vs. isothermal) under which the black hole evolves. The key contribution is the identification of nonmonotonic behavior in image size along isotherms, which allows for distinguishing between different thermodynamic ensembles and provides a new way to probe black hole thermodynamics.
Reference

Image size varies monotonically with the horizon radius along isobars, whereas it exhibits nonmonotonic behavior along isotherms.

Research#physics🔬 ResearchAnalyzed: Jan 4, 2026 08:29

Perturbation theory for gravitational shadows in Kerr-like spacetimes

Published:Dec 30, 2025 10:18
1 min read
ArXiv

Analysis

This article likely presents a theoretical analysis using perturbation theory to study the behavior of gravitational shadows in spacetimes similar to the Kerr spacetime (which describes rotating black holes). The use of perturbation theory suggests an attempt to approximate solutions to complex equations by starting with a simpler, known solution and adding small corrections. The focus on gravitational shadows indicates an interest in understanding how light bends and interacts with the strong gravitational fields near black holes.

Key Takeaways

    Reference

    The article is based on research published on ArXiv, a repository for scientific preprints.

    Analysis

    This paper introduces two new high-order numerical schemes (CWENO and ADER-DG) for solving the Einstein-Euler equations, crucial for simulating astrophysical phenomena involving strong gravity. The development of these schemes, especially the ADER-DG method on unstructured meshes, is a significant step towards more complex 3D simulations. The paper's validation through various tests, including black hole and neutron star simulations, demonstrates the schemes' accuracy and stability, laying the groundwork for future research in numerical relativity.
    Reference

    The paper validates the numerical approaches by successfully reproducing standard vacuum test cases and achieving long-term stable evolutions of stationary black holes, including Kerr black holes with extreme spin.

    Analysis

    This article likely discusses theoretical physics, specifically the intersection of quantum mechanics and general relativity, focusing on how gravitational waves could reveal information about black holes that are modified by quantum effects. The use of 'periodic orbits' suggests the analysis of specific orbital patterns to detect these signatures. The source, ArXiv, indicates this is a pre-print research paper.
    Reference

    Analysis

    This paper investigates the behavior of charged Dirac fields around Reissner-Nordström black holes within a cavity. It focuses on the quasinormal modes, which describe the characteristic oscillations of the system. The authors derive and analyze the Dirac equations under specific boundary conditions (Robin boundary conditions) and explore the impact of charge on the decay patterns of these modes. The study's significance lies in its contribution to understanding the dynamics of quantum fields in curved spacetime, particularly in the context of black holes, and the robustness of the vanishing energy flux principle.
    Reference

    The paper identifies an anomalous decay pattern where excited modes decay slower than the fundamental mode when the charge coupling is large.

    Analysis

    This paper addresses a crucial problem in gravitational wave (GW) lensing: accurately modeling GW scattering in strong gravitational fields, particularly near the optical axis where conventional methods fail. The authors develop a rigorous, divergence-free calculation using black hole perturbation theory, providing a more reliable framework for understanding GW lensing and its effects on observed waveforms. This is important for improving the accuracy of GW observations and understanding the behavior of spacetime around black holes.
    Reference

    The paper reveals the formation of the Poisson spot and pronounced wavefront distortions, and finds significant discrepancies with conventional methods at high frequencies.

    Analysis

    This paper addresses the challenge of explaining the early appearance of supermassive black holes (SMBHs) observed by JWST. It proposes a novel mechanism where dark matter (DM) interacts with Population III stars, causing them to collapse into black hole seeds. This offers a potential solution to the SMBH formation problem and suggests testable predictions for future experiments and observations.
    Reference

    The paper proposes a mechanism in which non-annihilating dark matter (DM) with non-gravitational interactions with the Standard Model (SM) particles accumulates inside Population III (Pop III) stars, inducing their premature collapse into BH seeds having the same mass as the parent star.

    Analysis

    This paper investigates quantum correlations in relativistic spacetimes, focusing on the implications of relativistic causality for information processing. It establishes a unified framework using operational no-signalling constraints to study both nonlocal and temporal correlations. The paper's significance lies in its examination of potential paradoxes and violations of fundamental principles like Poincaré symmetry, and its exploration of jamming nonlocal correlations, particularly in the context of black holes. It challenges and refutes claims made in prior research.
    Reference

    The paper shows that violating operational no-signalling constraints in Minkowski spacetime implies either a logical paradox or an operational infringement of Poincaré symmetry.

    Analysis

    This article likely presents a theoretical physics research paper. The title suggests an investigation into the properties of black holes within a specific theoretical framework (K-essence-Gauss-Bonnet gravity). The focus seems to be on scalar charges and kinetic screening mechanisms, which are relevant concepts in understanding the behavior of gravity and matter in extreme environments. The source being ArXiv indicates it's a pre-print server, suggesting the work is preliminary and awaiting peer review.
    Reference

    Critique of Black Hole Thermodynamics and Light Deflection Study

    Published:Dec 29, 2025 16:22
    1 min read
    ArXiv

    Analysis

    This paper critiques a recent study on a magnetically charged black hole, identifying inconsistencies in the reported results concerning extremal charge values, Schwarzschild limit characterization, weak-deflection expansion, and tunneling probability. The critique aims to clarify these points and ensure the model's robustness.
    Reference

    The study identifies several inconsistencies that compromise the validity of the reported results.

    Analysis

    This paper explores the implications of non-polynomial gravity on neutron star properties. The key finding is the potential existence of 'frozen' neutron stars, which, due to the modified gravity, become nearly indistinguishable from black holes. This has implications for understanding the ultimate fate of neutron stars and provides constraints on the parameters of the modified gravity theory based on observations.
    Reference

    The paper finds that as the modification parameter increases, neutron stars grow in both radius and mass, and a 'frozen state' emerges, forming a critical horizon.

    Ge Hole Spin Control Using Acoustic Waves

    Published:Dec 29, 2025 14:56
    1 min read
    ArXiv

    Analysis

    This article reports on research related to controlling the spin of holes in Germanium (Ge) using acoustic waves. The source is ArXiv, indicating a pre-print or research paper. The topic is within the realm of condensed matter physics and potentially spintronics.
    Reference

    Analysis

    This paper establishes a connection between quasinormal modes (QNMs) and grey-body factors for Kerr black holes, a significant result in black hole physics. The correspondence is derived using WKB methods and validated against numerical results. The study's importance lies in providing a theoretical framework to understand how black holes interact with their environment by relating the characteristic oscillations (QNMs) to the absorption and scattering of radiation (grey-body factors). The paper's focus on the eikonal limit and inclusion of higher-order WKB corrections enhances the accuracy and applicability of the correspondence.
    Reference

    The paper derives WKB connection formulas that relate Kerr quasinormal frequencies to grey-body transmission coefficients.

    Analysis

    This paper investigates the properties of a 'black hole state' within a quantum spin chain model (Heisenberg model) using holographic principles. It's significant because it attempts to connect concepts from quantum gravity (black holes) with condensed matter physics (spin chains). The study of entanglement entropy, emptiness formation probability, and Krylov complexity provides insights into the thermal and complexity aspects of this state, potentially offering a new perspective on thermalization and information scrambling in quantum systems.
    Reference

    The entanglement entropy grows logarithmically with effective central charge c=5.2. We find evidence for thermalization at infinite temperature.

    Love Numbers of Acoustic Black Holes

    Published:Dec 29, 2025 08:48
    1 min read
    ArXiv

    Analysis

    This paper investigates the tidal response of acoustic black holes (ABHs) by calculating their Love numbers for scalar and Dirac perturbations. The study focuses on static ABHs in both (3+1) and (2+1) dimensions, revealing distinct behaviors for bosonic and fermionic fields. The results are significant for understanding tidal responses in analogue gravity systems and highlight differences between integer and half-integer spin fields.
    Reference

    The paper finds that in (3+1) dimensions the scalar Love number is generically nonzero, while the Fermionic Love numbers follow a universal power-law. In (2+1) dimensions, the scalar field exhibits a logarithmic structure, and the Fermionic Love number retains a simple power-law form.

    Analysis

    This paper introduces and analyzes the Lense-Thirring Acoustic Black Hole (LTABH), an analogue model for black holes. It investigates the spacetime geometry, shadow characteristics, and frame-dragging effects. The research is relevant for understanding black hole physics through analogue models in various physical systems.
    Reference

    The rotation parameter 'a' is more relevantly affecting the optical shadow radius (through a right shift), while the acoustic shadow retains its circular shape.

    Analysis

    This paper explores the implications of black hole event horizons on theories of consciousness that emphasize integrated information. It argues that the causal structure around a black hole prevents a single unified conscious field from existing across the horizon, leading to a bifurcation of consciousness. This challenges the idea of a unified conscious experience in extreme spacetime conditions and highlights the role of spacetime geometry in shaping consciousness.
    Reference

    Any theory that ties unity to strong connectivity must therefore accept that a single conscious field cannot remain numerically identical and unified across such a configuration.

    Research#Astrophysics🔬 ResearchAnalyzed: Jan 4, 2026 06:49

    Vacuum Decay around Black Holes formed from Collapse

    Published:Dec 28, 2025 19:19
    1 min read
    ArXiv

    Analysis

    This article likely discusses the theoretical physics of vacuum decay in the extreme gravitational environment near black holes formed through stellar collapse. It would involve complex calculations and simulations based on general relativity and quantum field theory. The research likely explores the stability of the vacuum state and potential particle creation in these regions.
    Reference

    Analysis

    This paper provides a concise review of primordial black hole (PBH) formation mechanisms originating from first-order phase transitions in the early universe. It's valuable for researchers interested in PBHs and early universe cosmology, offering a consolidated overview of various model-dependent and independent mechanisms. The inclusion of model-specific examples aids in understanding the practical implications of these mechanisms.
    Reference

    The paper reviews the creation mechanism of primordial black holes from first order phase transitions.

    Analysis

    This paper establishes a fundamental geometric constraint on the ability to transmit quantum information through traversable wormholes. It uses established physics principles like Raychaudhuri's equation and the null energy condition to derive an area theorem. This theorem, combined with the bit-thread picture, provides a rigorous upper bound on information transfer, offering insights into the limits of communication through these exotic spacetime structures. The use of a toy model (glued HaPPY codes) further aids in understanding the implications.
    Reference

    The minimal throat area of a traversable wormhole sets the upper bound on information transfer.

    Analysis

    This paper explores the formation of primordial black holes (PBHs) within a specific theoretical framework (Higgs hybrid metric-Palatini model). It investigates how large density perturbations, originating from inflation, could have led to PBH formation. The study focuses on the curvature power spectrum, mass variance, and mass fraction of PBHs, comparing the results with observational constraints and assessing the potential of PBHs as dark matter candidates. The significance lies in exploring a specific model's predictions for PBH formation and its implications for dark matter.
    Reference

    The paper finds that PBHs can account for all or a fraction of dark matter, depending on the coupling constant and e-folds number.

    Analysis

    This paper explores the microstructure of Kerr-Newman black holes within the framework of modified f(R) gravity, utilizing a novel topological complex analytic approach. The core contribution lies in classifying black hole configurations based on a discrete topological index, linking horizon structure and thermodynamic stability. This offers a new perspective on black hole thermodynamics and potentially reveals phase protection mechanisms.
    Reference

    The microstructure is characterized by a discrete topological index, which encodes both horizon structure and thermodynamic stability.

    Analysis

    This paper addresses inconsistencies in the study of chaotic motion near black holes, specifically concerning violations of the Maldacena-Shenker-Stanford (MSS) chaos-bound. It highlights the importance of correctly accounting for the angular momentum of test particles, which is often treated incorrectly. The authors develop a constrained framework to address this, finding that previously reported violations disappear under a consistent treatment. They then identify genuine violations in geometries with higher-order curvature terms, providing a method to distinguish between apparent and physical chaos-bound violations.
    Reference

    The paper finds that previously reported chaos-bound violations disappear under a consistent treatment of angular momentum.

    Analysis

    This paper investigates the impact of higher curvature gravity on black hole ringdown signals. It focuses on how deviations from General Relativity (GR) become more noticeable in overtone modes of the quasinormal modes (QNMs). The study suggests that these deviations, caused by modifications to the near-horizon potential, can be identified in ringdown waveforms, even when the fundamental mode and early overtones are only mildly affected. This is significant because it offers a potential way to test higher curvature gravity theories using gravitational wave observations.
    Reference

    The deviations of the quasinormal mode (QNM) frequencies from their general relativity (GR) values become more pronounced for overtone modes.

    Analysis

    This paper explores new black hole solutions in anti-de Sitter (AdS) spacetime using modified nonlinear electrodynamics (ModMax and ModAMax). It investigates the thermodynamic properties, stability, and Joule-Thomson expansion of these black holes, considering the impact of ModMax/ModAMax parameters and topology. The study's significance lies in its contribution to understanding black hole thermodynamics and its potential applications in heat engine analysis.
    Reference

    The paper examines how the parameters of the ModMax and ModAMax fields, as well as the topological constant, affect the black hole solutions, thermodynamic quantities, and local and global thermal stabilities.

    Evidence for Stratified Accretion Disk Wind in AGN

    Published:Dec 27, 2025 14:49
    1 min read
    ArXiv

    Analysis

    This paper provides observational evidence supporting the existence of a stratified accretion disk wind in Active Galactic Nuclei (AGN). The analysis of multi-wavelength spectroscopic data reveals distinct emission line profiles and kinematic signatures, suggesting a structured outflow. This is significant because it provides constraints on the geometry and physical conditions of AGN winds, which is crucial for understanding the processes around supermassive black holes.
    Reference

    High-ionization lines (e.g., Civ λ1549) exhibit strong blueshifts and asymmetric profiles indicative of fast, inner winds, while low-ionization lines (e.g., Hβ, Mgii λ 2800) show more symmetric profiles consistent with predominant emission from slower, denser regions farther out.

    Analysis

    This paper explores the relationship between higher-form symmetries, scalar charges, and black hole thermodynamics in the context of 5-dimensional supergravity and its dimensional reduction to 4-dimensional supergravity. It investigates the role of symmetries, including higher-form symmetries, in determining the behavior of black holes and their thermodynamic properties. The study focuses on the connection between 5D and 4D quantities and the constraints required for consistency. The results are generalized to Einstein-Maxwell-like theories.
    Reference

    The paper finds that a 2-dimensional subgroup of SL(2,R) acts as a higher-form symmetry group and computes Smarr formulas for black holes, showing their equivalence under specific field constraints.

    Scalar-Hairy AdS Black Hole Phase Transition

    Published:Dec 27, 2025 01:57
    1 min read
    ArXiv

    Analysis

    This paper investigates the phase transitions of scalar-hairy black holes in asymptotically anti-de Sitter spacetime within the Einstein-Maxwell-scalar model. It explores the emergence of different hairy black hole solutions (scalar-hairy and tachyonic-hairy) and their phase diagram, highlighting a first-order phase transition with a critical point. The study's significance lies in understanding the behavior of black holes in modified gravity theories and the potential for new phases and transitions.
    Reference

    The phase diagram reveals a first-order phase transition line between the tachyonic-hairy and scalar-hairy phases, originating at a critical point in the extreme temperature and chemical potential regime.

    Traversable Ghost Wormholes Explored

    Published:Dec 26, 2025 19:40
    1 min read
    ArXiv

    Analysis

    This paper explores the theoretical possibility of 'ghost stars' within the framework of traversable wormholes. It investigates how these objects, characterized by arbitrarily small mass and negative energy density, might exist within wormhole geometries. The research highlights potential topological obstructions to their straightforward realization and provides a concrete example using a Casimir-like wormhole. The analysis of the Penrose-Carter diagram further illustrates the properties of the resulting geometry.
    Reference

    The paper demonstrates that a Casimir-like traversable wormhole can be naturally constructed within this framework.

    Analysis

    This paper investigates how smoothing the density field (coarse-graining) impacts the predicted mass distribution of primordial black holes (PBHs). Understanding this is crucial because the PBH mass function is sensitive to the details of the initial density fluctuations in the early universe. The study uses a Gaussian window function to smooth the density field, which introduces correlations across different scales. The authors highlight that these correlations significantly influence the predicted PBH abundance, particularly near the maximum of the mass function. This is important for refining PBH formation models and comparing them with observational constraints.
    Reference

    The authors find that correlated noises result in a mass function of PBHs, whose maximum and its neighbourhood are predominantly determined by the probability that the density contrast exceeds a given threshold at each mass scale.

    Research#Black Holes🔬 ResearchAnalyzed: Jan 10, 2026 07:13

    Analyzing Black Hole Births: A Contact Geometry Perspective

    Published:Dec 26, 2025 14:55
    1 min read
    ArXiv

    Analysis

    This article, sourced from ArXiv, discusses the classification and stability of black hole event horizon births using contact geometry. The work is likely highly theoretical, focusing on mathematical modeling rather than immediately practical applications.
    Reference

    The article's topic is the classification and stability of black hole event horizon births.

    Analysis

    This paper introduces a novel method to estimate the orbital eccentricity of binary black holes (BBHs) by leveraging the measurable spin-orbit misalignment. It establishes a connection between spin-tilt and eccentricity, allowing for the reconstruction of formation eccentricity even without direct measurements. The method is applied to existing gravitational wave events, demonstrating its potential. The paper highlights the importance of this approach for understanding BBH formation and the impact of future detectors.
    Reference

    By measuring this spin-tilt using gravitational waves, we can not only constrain the natal kick, but we can also reconstruct the binary's formation eccentricity.