376 papers
This paper demonstrates that time-dependent string compactifications can satisfy the higher-dimensional Null Energy Condition required by worldsheet symmetry while allowing the lower-dimensional effective description to violate it, thereby enabling bouncing cosmologies and scale-separated solutions.
This paper investigates the observational properties of a Schwarzschild black hole surrounded by a dark matter halo, analyzing its spacetime structure, particle dynamics, and weak gravitational lensing effects in plasma to constrain black hole parameters using Event Horizon Telescope data.
This paper investigates the impact of Barrow's fractal entropy parameter on the Joule-Thomson expansion and inversion temperature of quantum-corrected AdS-Reissner-Nordström black holes in Kiselev spacetime, utilizing numerical solutions to analyze temperature-pressure relationships and isenthalpic curves.
This paper resolves the Einstein-scalar field conformal constraint equations under spherically symmetric and harmonic assumptions, revealing that while solutions on compact manifolds like the sphere exhibit nonexistence and instability in near-CMC regimes, the equations are always solvable on Euclidean and hyperbolic manifolds, thereby supporting the conformal method's utility for asymptotically flat and hyperbolic initial data.
This paper establishes a correspondence between the gravitational phase space at null infinity and near a black hole horizon, identifying celestial symmetries in the latter's subleading phase space to reveal an infinite tower of conserved charges and new gravitational observables.
This paper extends a geometric approach to light rings from spherically symmetric to general axially symmetric spacetimes by utilizing Randers-Finsler optical geometry to determine circular photon orbits via vanishing geodesic curvature and classify their stability through intrinsic flag curvature, while rigorously demonstrating its equivalence to the conventional effective potential method.
This paper establishes a definition of quasi-local energy for initial data sets with an umbilic second fundamental form in an expanding de Sitter background and proves its positivity for certain bounded values of the cosmological constant by adapting the Liu-Yau energy framework.
This paper numerically demonstrates that the path-sum-based causal set scalar propagator construction accurately reproduces the continuum result in (1+1)-dimensional Anti-de Sitter spacetime without requiring modifications to the flat-spacetime jump amplitudes, thereby validating the formalism's applicability to curved Lorentzian manifolds.
This paper presents a proof of the reverse isoperimetric inequality for black holes in Einstein gravity with using a geometric-analytic approach, demonstrating that the reversal of the usual inequality stems from the curved background structure dictated by Einstein's equations.
This paper generalizes a recent geometric approach for studying massive particle surfaces to stationary spacetimes by utilizing a projected 2-dimensional Riemannian metric to characterize null and timelike trajectories via intrinsic curvatures, thereby enabling the analysis of black hole shadows in non-asymptotically flat solutions like Kerr and Kerr-(A)dS.
This paper demonstrates that gravitational waveforms from binary stars orbiting a supermassive black hole (B-EMRIs) exhibit distinct high-frequency oscillations and are credibly distinguishable from standard extreme mass ratio inspirals by space-based detectors, particularly when gravito-electromagnetic forces are included in the analysis.
The paper argues that the "problem of time" in quantum cosmology causes the disappearance of the time variable necessary to define the universe's age, thereby stripping classical models of their ability to make the physically meaningful prediction that the universe is 13.8 billion years old and suggesting a fundamental flaw in this approach.
This paper derives a closed-form analytic expression showing that the interaction between a static point mass supported by a string and Hawking radiation gravitons yields a finite response rate in the Unruh state due to the black hole's size acting as an infrared cutoff, while the response in the Hartle-Hawking state vanishes, resulting in identical total rates for both states unlike the case for massless scalar fields.
This paper investigates one-loop mass corrections for interacting string states in the NS-NS sector of Type-II theories, specifically deriving closed-form expressions for states in the first Regge trajectory up to level by constructing vertex operators, utilizing elliptic functions, and applying the -prescription to regularize infrared divergences.
This paper develops a covariant formulation of the strong deflection limit for massive particles in static, spherically symmetric spacetimes, demonstrating that the logarithmic divergence of the deflection angle is governed by the radial instability exponent of the critical orbit, which can be expressed geometrically through local curvature data and matter properties.
This paper proposes a globally stable, ghost-free hyperbolic square-root deformation of the Starobinsky model that eliminates strong-coupling singularities while preserving successful inflationary predictions consistent with current observational constraints.
This paper presents a fully covariant derivation of the classical log soft graviton theorem using Einstein equations and matching conditions across timelike, spatial, and null infinity, demonstrating that the asymmetry between future and past hard components arises from a discontinuity in the gravitational field at spatial infinity.
This paper presents a global dynamical systems analysis of quadratic cosmology with a perfect fluid in spatially flat models, comparing the Jordan and Einstein frames to characterize orbit structures, desingularize fixed points, and identify which solutions are globally conformally mapped between the two frames.
This paper investigates the perturbation dynamics of massless scalar and electromagnetic fields on magnetically charged de Sitter black holes in Einstein-Euler-Heisenberg gravity by calculating quasinormal frequencies and greybody factors to analyze the effects of magnetic charge, cosmological constant, coupling parameter, and multipole number using the asymptotic iteration, WKB, and Bernstein spectral methods.
This paper investigates how quintessence fields and observer motion influence black hole shadows by deriving analytical expressions for key spacetime features and demonstrating that the apparent angular size of the shadow depends sensitively on whether the observer is static or freely falling, a distinction crucial for accurately interpreting Event Horizon Telescope observations of M87*.