Celio Rodrigues Muniz

The thermodynamic interpretation of gravity suggests that modifications of horizon entropy can be encoded in effective geometries and matter distributions. Motivated by the entropy-geometry correspondence, we investigate Morris-Thorne wormholes constructed from density profiles associated with Barrow, Tsallis, Kaniadakis, logarithmic, and exponential black-hole entropies. The wormhole construction retains each entropy-induced density as input to the shape-function equation, while the radial and tangential pressures are reconstructed independently from the wormhole field equations, a barotropic radial equation of state, anisotropic conservation, and throat regularity. Barrow and Tsallis yield algebraic negative-density distributions; Kaniadakis and exponential corrections produce localized profiles; and the logarithmic sector admits both negative-density and positive-density phantom-like regimes. For every regular configuration considered, radial null energy condition violation at the throat follows from the flare-out condition. Its areal-volume integral is finite and negative for every nonzero deformation: it becomes unbounded when the regular Barrow, Tsallis, and Kaniadakis branches approach their undeformed values, but remains finite in the logarithmic and exponential limits. Removing the density deformation also fails to commute with taking the infinite-radius limit in the Barrow, Tsallis, and Kaniadakis sectors, whereas the two operations agree for the logarithmic and exponential sectors in their pole-free domains. The selected entropy-induced densities can therefore be embedded consistently in traversable-wormhole reconstructions, with the pressure sector fixed by the wormhole geometry and the global source behavior controlling both the asymptotic mass and the integrated radial exoticity.

We construct static, spherically symmetric, and asymptotically flat colored black holes in four-dimensional Einstein gravity coupled to logarithmic nonlinear Yang–Mills theory with gauge group SU(2). Unlike exact solutions based on the Wu–Yang ansatz, these configurations contain a dynamical radial gauge amplitude and arise from a fully coupled boundary-value problem. An integral identity establishes that nontrivial magnetically neutral solutions must be nodal. We obtain the fundamental one-node branch and verify its smooth convergence to the ordinary Einstein–Yang–Mills colored black hole in the weakly nonlinear regime. Increasing the logarithmic nonlinearity lowers the ADM mass, raises the Hawking temperature, and shifts the gauge-field node outward. No termination of the branch is detected within the parameter and radial ranges investigated; instead, the exterior geometry approaches Schwarzschild on fixed radial domains while the colored field develops an increasingly extended tail. A characteristic analysis shows that sufficiently strong logarithmic deformations lose hyperbolicity near the event horizon, restricting their dynamical interpretation. Although the non-Abelian hair carries no independent asymptotic charge, it leaves a subleading gravitational imprint. For representative solutions within the investigated parameter and radial ranges, the numerical interior evolution detects neither an inner Cauchy horizon nor oscillatory mass inflation. Their mass function approaches a finite limit, while the center remains a Schwarzschild-type spacelike curvature singularity. The recovery of the linear theory is nonuniform near the center, where every finite nonlinear deformation eventually enters the strongly logarithmic regime. Temperature turning points also mark changes of local thermodynamic stability, without implying a global phase transition.

The so-called generalized Ellis–Bronnikov (EB) wormhole is a modification of the standard EB solution, in which a parameter m > 2 is introduced-recovering the original EB geometry when m = 2 . In this work, we investigate the properties of this spacetime by analyzing its embedding diagrams and how they are affected by variations in the parameter m . Furthermore, we study the accretion of dust onto this geometry, showing that, unlike in black hole scenarios, the radial infall velocity of the dust decreases as it approaches the wormhole throat, with this deceleration becoming increasingly abrupt for larger values of m . Our results also demonstrate that the mass of the wormhole generally decreases due to the accretion process, a finding that aligns with recent works in the literature for EB-type geometries. This mass loss, coupled with the characteristic accumulation of matter near the throat, highlights the unique dynamical response of traversable wormholes to baryonic influx. As a main result, we demonstrate that this geometry arises as an exact solution of general relativity when considering the combined presence of a phantom scalar field and a magnetic or electric source.

In this work, we propose a modified Schwarzschild geometry inspired by the Asymptotic Safety approach to quantum gravity, in which the Newtonian coupling becomes a running quantity depending on the radial coordinate. We employ an infrared cutoff at the proper distance and obtain a new quantum-corrected black hole metric. We provide a thermodynamical analysis, first using standard methods and then proceeding to a geometrothermodynamical study of the phase space and to a topological analysis of phase transitions. We also calculate the grey-body factors of our solution, providing exact lower bounds in the quantum-corrected transmission coefficients. Finally, we present the shadow size and intensity profile of our solution, showing its consistency with current observational constraints.

In this paper, we study the polymer black hole solution surrounded by a quintessence field. The influence of quintessence on the polymer black hole is investigated through its thermodynamic properties, such as the Hawking temperature, entropy, and specific heat, which allow us to address the question of thermodynamic stability. We then calculate bounds on the electromagnetic greybody factors and photon emission rates of the black hole, highlighting the interplay between quintessence and quantum gravity effects in determining these phenomena. We also examine the effects of quintessence and quantum gravity on the geodesics and shadows of massless particles around the black hole. Our results are further compared with observational data of both the Sagittarius A* and M87* black holes from the Event Horizon Telescope (EHT) collaboration.

We propose a new strategy for constructing traversable wormholes using Padé approximants, addressing the limitations of the standard ‘geometry‐first’ approach. We demonstrate that directly expanding the shape function can introduce spurious poles and fails to guarantee fidelity to the target matter distribution. To resolve these issues, we introduce a ‘matter‐first’ method, where the density profile is approximated by rational functions and then integrated to derive the shape function. This approach ensures that the resulting spacetime exactly reproduces the intended matter content while providing analytical closed‐form solutions, as Padé approximants are inherently integrable. We apply this framework to the Dekel–Zhao dark matter halo, showing that the matter‐first construction yields globally regular geometries that satisfy asymptotic flatness and flare‐out conditions without the artificial singularities found in the geometry‐first scheme. Finally, we analyze the energy conditions, confirming that the method provides a controlled and consistent description of the wormhole throat and its supporting exotic matter.