Freddy Permana Zen

A bstract: We investigate the holographic timelike entanglement entropy (HTEE) and timelike subregion complexity of a thermal CFT _d deformed by a relevant scalar operator ϕ ₀ , dual to a hairy black hole in AdS _{d +1} . We employ the prescription of merging spacelike and timelike surfaces at the interior, constructing an extremal surface homologous to a boundary timelike subsystem with a time interval ∆ t . Consequently, this deformation breaks the invariance of the imaginary component of HTEE observed in pure AdS ₃ and BTZ geometry, introducing a nontrivial dependence on ∆ t . At small ∆ t , we derive analytical expressions that are in agreement with numerical results, and observe partial consistency with analytic continuation to temporal or spacelike entanglement entropy at the level of the near-boundary expansion. However, analytic continuation of CFT temporal entanglement entropy fails to reproduce the HTEE calculations under boundary deformation, even in d = 2. Furthermore, we extend the numerical calculations to higher dimensions ( d = 3). In addition, we study holographic timelike subregion complexity within the complexity=volume conjecture and find that it remains real-valued, providing a complementary geometric probe of the black hole interior. In particular, for the BTZ black hole, we analytically show that the UV-finite term of the subregion complexity receives its entire contribution from the interior region alone.

The mass–radius relation, moment of inertia and tidal love numbers (TLNs) of anisotropic neutron stars (NSs) have been investigated in [ ] gravity by imposing two equations of state (EoS). We use the simplest form [ ] model and adopt the anisotropy approach called Horvat model. To examine the viability of our calculations, we utilize the constraints from GW170817 and GW190814 observations. Moreover, we consider three values of [ ], i.e. [ ], [ ], [ ] and four anisotropy parameters [ ], i.e. [ ], [ ], [ ], [ ]. Our findings suggest that all physical quantities depend on both parameters [ ] and [ ]. Nevertheless, the impact of [ ] is much more significant than [ ]. The calculation of masses satisfies each used constraint for specific values of [ ] and [ ]. In the case of the moment of inertia, the results are compatible with the constraint obtained from radio observation of heavy pulsar. On the other hand, the tidal deformability of the NSs composed of one EoS satisfies the GW170817 constraint while the NSs composed of the other one EoS are too small. These small numbers can be interpreted as the property of secondary object observed in GW190814. As a result, our theoretical investigation of NSs constructed with two EoS can be NSs candidates for GW170817 and GW190814, respectively.

Observations indicate that the magnetic fields on neutron stars (NSs) lie in the range of [ ]–[ ] G. We investigate rotating NSs with chaotic magnetic fields in both general relativity (GR) and Rastall gravity (RG). The equation of state (EOS) of NS matter is formulated within the framework of quantum hadrodynamics (QHD). The Hartle–Thorne formalism, extended to RG, is employed as an approximation for describing rotating NSs, while the magnetic field is modeled through an ansatz in which it is coupled to the energy density. We find that at high masses, neither rotation nor the Rastall parameter significantly affects the total mass, whereas the magnetic field strength can increase the maximum allowed mass. At lower masses, both the magnetic field and an increasing Rastall parameter reduce the stellar radius in the static configuration. Although higher angular velocities enhance stellar deformation, both magnetic field and larger Rastall parameter tend to suppress it. Regarding the moment of inertia, the Rastall parameter has little impact, whereas the magnetic field strength can increase it within the mass range [ ]–[ ]. All parameters considered in this study are consistent with observational constraints on the moment of inertia obtained from radio observations of massive pulsars.

In this work, we investigate the tidal response of both static and rotating black holes in anti de-Sitter spacetime. We perform the neutral scalar field perturbation for Schwarzschild and Kerr black holes. On the other hand, charged scalar field are used for perturbing Reissner-Nordstrom and Kerr-Newman black holes. We find that the tidal Love number for all black holes are always nonvanishing due to the presence of cosmological constant. In contrast, tidal dissipation can vanish for certain conditions depending on the scalar field's frequency and the black hole's parameters.

We analyze how the axion parameter, the Einstein-Maxwell-Scalar coupling constant, and charge density from Maxwell field affect the chaotic feature of a charged hairy black hole, as characterized by the quantum Lyapunov exponent. Due to relevant deformation in the boundary theory coming from a scalar bulk field, the bulk solution flows into more general Kasner spacetime in the interior of the black hole, near the singularity. We inject charged shock waves from the asymptotic boundary and calculate the out-of-time-ordered correlators holographically, which can probe chaos. The ratio of the quantum Lyapunov exponent with respect to the surface gravity is reduced as the deformation parameter increased, while the Lyapunov exponent of the deformed geometry can be greater than the axion Reissner-Nordström case when the deformation parameter is large enough. We also study how this deformation, along with the added parameters, affect other chaotic properties such as the butterfly velocity and the scrambling time delay. Furthermore, we also analyze the region where Kasner spacetime undergoes Kasner inversion/transition deeper inside the black hole.