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Erdinç Ulaş Saka

Publications and source records attributed to Erdinç Ulaş Saka.

8 recordsLinked to original sources
arXiv2026

Extended Generalized Uncertainty Principle Corrections to Five Dimensional Einstein Gauss Bonnet Black Hole Thermodynamics

We study the thermodynamics of asymptotically flat five dimensional Einstein Gauss Bonnet black holes within the framework of the extended generalized uncertainty principle (EGUP). The geometry dependent localization scale is fixed by requiring the undeformed relation to reproduce the surface gravity temperature. The resulting expression consistently recovers the GUP, EUP, and semiclassical limits, while imposing a joint constraint on the minimum length and minimum momentum parameters. Due to the nonmonotonic behavior of the effective localization scale, the reality condition does not generically yield a unique minimum horizon radius. Depending on the parameter values, the admissible domain may remain connected, develop a degenerate critical radius, or split into two disconnected branches. We derive the entropy, heat capacity, and Helmholtz free energy, and analyze their behavior numerically. The Gauss Bonnet coupling shifts and suppresses the near horizon temperature maximum, whereas the EUP sector induces a temperature minimum followed by linear growth at large radius. In the two branch regime, the outer endpoint exhibits finite temperature and vanishing heat capacity but is approached from the locally unstable side, and should therefore be interpreted as a limiting thermodynamic configuration rather than a dynamically established remnant. Finally, we show that the perturbative entropy deviates from the exact result at large radius, and that the leading GUP entropy correction persists in the Einstein gravity limit.

gr-qc↗
arXiv2026

Orbital, Shadow, and Thin-Disk Signatures of a Regular Black Hole with Gravitational Self-Energy

We investigate geodesic motion, shadow observables and thin-disk accretion for the regular black hole generated by a non-local gravitational self-energy contribution. The geometry is controlled by a zero-point length and can be followed smoothly from the Schwarzschild limit to a cold extremal remnant. We compute the photon ring, critical impact parameter, apparent shadow radius, null Lyapunov exponent, innermost stable circular orbit, orbital frequencies and Novikov-Thorne flux profile. As the self-energy scale grows, both the photon ring and the ISCO move outward, while the photon-ring frequency and instability exponent decrease. The horizon-normalized shadow area increases by about a factor of 2.7 for the near-extremal benchmark, although the same shadow radius decreases when normalized by the ADM mass. The ISCO binding efficiency grows modestly, whereas the zero-torque thin-disk flux peak moves outward and falls to about 61% of the Schwarzschild peak as the solution approaches the remnant regime. These trends identify a coherent set of optical, orbital and accretion signatures of the gravitational-self-energy regularization.

gr-qc↗
arXiv2026

Hernquist distribution of matter as a source of black-hole geometry

It was recently demonstrated that imposing the condition $P_{r} = -ρ$ on the radial pressure of a galactic halo can lead to regular black-hole solutions for certain density profiles, such as the Dehnen and Einasto models. In the present work, we show that some of the most commonly used halo profiles, including the Hernquist model, do not yield regular geometries under the same condition, but instead support black-hole solutions that retain a central singularity

gr-qc↗
arXiv2025

Gravitational quasinormal modes of Dymnikova black holes

We investigate gravitational quasinormal modes of the Dymnikova black hole, a regular spacetime in which the central singularity is replaced by a de Sitter core. This geometry, originally proposed as a phenomenological model, also arises naturally in the framework of Asymptotically Safe gravity, where quantum corrections lead to a scale-dependent modification of the Schwarzschild solution. Focusing on axial gravitational perturbations, we compute the dominant quasinormal frequencies using the WKB method with Padé approximants and verify the results with time-domain integration. We find that the introduction of the quantum parameter $l_{\rm cr}$ leads to systematic deviations from the Schwarzschild spectrum: the real oscillation frequency decreases as $l_{\rm cr}$ increases, while the damping rate also becomes smaller, implying longer-lived modes. In the limit of large $l_{\rm cr}$, the quasinormal spectrum smoothly approaches the Schwarzschild case. These results suggest that even though the corrections are localized near the horizon, they leave imprints in the gravitational-wave ringdown which may become accessible to observation with future high-precision detectors.

gr-qc↗
arXiv2025

Regular black hole sourced by the Dehnen-type distribution of matter: The sound of the event horizon

We compute the fundamental and overtone quasinormal modes of a regular, asymptotically flat black hole supported by a Dehnen-type matter halo. Gravitational perturbations in this background split into two distinct axial sectors, and our analysis confirms that the presence of the halo parameter $a$ breaks the isospectrality that holds in vacuum. The dependence of the quasinormal spectrum on $a$ is moderate for the fundamental modes and even weaker for the overtones, which approach one another in the complex-frequency plane as the halo parameter increases. No enhancement or rapid growth of overtone amplitudes is observed, indicating that the halo does not induce the type of strong near-horizon effects characteristic of quantum-corrected or exotic compact objects. Overall, our results show that the dark-matter halo introduces controlled and comparatively mild modifications to the ringdown spectrum while preserving its qualitative structure.

gr-qc↗
arXiv2025

Proper-Time Approach in Asymptotic Safety via Black Hole Quasinormal Modes and Grey-body Factors

We study the quasinormal mode spectrum and grey-body factors of black holes in an effectively quantum-corrected spacetime, focusing on the influence of near-horizon modifications on observable quantities. Employing scalar, electromagnetic, and Dirac test fields, we analyze the perturbation equations and extract the fundamental quasinormal frequencies using both the 6th-order WKB method with Padé resummation and time-domain integration. Our results show that quantum corrections near the horizon significantly affect the real and imaginary parts of the quasinormal modes, particularly for low multipole numbers and in the near-extremal regime. We also verify the robustness of the correspondence between quasinormal modes and grey-body factors by comparing WKB results with those reconstructed from the dominant quasinormal modes. Across all field types and parameter ranges considered, the WKB method proves accurate within a few percent, confirming its reliability in probing the impact of near-horizon physics. These findings support the use of quasinormal ringing and Hawking radiation spectra as sensitive tools for testing quantum modifications of black hole spacetimes.

gr-qc↗
arXiv2023

Analysis of Direct and Indirect Detection of Fermionic Dark Matter of 6-Dimensional Effective Field Theory

We present an analysis of fermionic dark matter (DM) in the context of 6 dimensional Effective Field Theory (EFT). We also compared the result generated via the 6-dimensional EFT analysis with the current experimental results for dark matter searches. These experiments are methodically categorised as direct and indirect search and present some constraints on dark matter model parameters of 6-dimensional EFT. We constructed a new set of tools ensuring DM researches in various platforms. The model parameters are presented to guide DM production in colliders by taking account of the upper limits at direct and indirect searches. In this paper we apply our approach for fermionic case to test the verification of the method. There are various type of search methods for DM, each depends on type of interaction of dark matter with SM particles. Finally we analysed fermionic DM candidate of 6-dimensional Effective Field Theory (EFT) at the platforms of DM searches. A new set of numerical tools is specified for 6-dimensional fermionic DM model, and these tools are also tested.

hep-ph↗