TypeⅠcritical dynamical scalarization and descalarization in Einstein-Maxwell-scalar theory

We investigated the critical dynamical scalarization and descalarization of black holes within the framework of the EinsteinMaxwell-scalar theory featuring higher-order coupling functions.Both the critical scalarization and descalarization displayed first-order phase transitions.When examining the nonlinear dynamics near the threshold,we always observed critical solutions that are linearly unstable static scalarized black holes.The critical dynamical scalarization and descalarization share certain similarities with the typeⅠcritical gravitational collapse.However,their initial configurations,critical solutions,and final outcomes differ significantly.To provide further insights into the dynamical results,we conducted a comparative analysis involving static solutions and perturbative analysis.

Critical scalarization and descalarization of black holes in a generalized scalar-tensor theory

We study the critical dynamics in scalarization and descalarization in the fully nonlinear dynamical evolution in the class of theories with a scalar field coupling with both Gauss-Bonnet(GB) invariant and Ricci scalar. We explore the manner in which the GB term triggers black hole(BH) scalarization. A typical type Ⅰ critical phenomenon is observed, in which an unstable critical solution emerges at the threshold and acts as an attractor in the dynamical scalarization. For the descalarization, we reveal that a marginally stable attractor exists at the threshold of the first-order phase transition in shedding off BH hair. This is a new type Ⅰ critical phenomenon in the BH phase transition. Implications of these findings are discussed from the perspective of thermodynamic properties and perturbations for static solutions. We examine the effect of scalar-Ricci coupling on the hyperbolicity in the fully nonlinear evolution and observe that such coupling can suppress the elliptic region and enlarge parameter space in computations.

Onset of chaotic gravitational lensing in non-Kerr rotating black holes with quadrupole mass moment

In the electromagnetic channel,chaotic gravitational lensing is a peculiar phenomenon in strong gravita-tional lensing.In this study,we analyze the properties and emergence of chaotic gravitational lensing in the Manko-Novikov black hole spacetime.Aiming to better understand the underlying physics,we elaborate on the boundaries of the accessible region through analyses of the contours of the effective potentials.The latter is associated with the two roots of a quadratic equation.In particular,we explore its interplay with an ergoregion,which leads to specific features of the effective potentials,such as the emergence of a cuspy edge and the formation of a pocket,which serve as static constraints on the geodesics.Additionally,we investigate the properties of the radial and angular accelerations at the turning points in photon trajectories.The accelerations are further examined and may provide kinematic constraints on the geodesics,as argued herein.It is concluded that the onset of the chaotic lensing is significantly related to both con-straints;as a result,an arbitrary slight deviation in the incident photon is significantly amplified during evolution through an extensive period,demonstrating the complexity in the highly nonlinear deterministic gravitational system.

Entanglement wedge cross-section with Gauss-Bonnet corrections and thermal quench

The entanglement wedge cross section(EWCS) is numerically investigated statically and dynamically in a five-dimension Ad SVaidya spacetime with Gauss-Bonnet(GB) corrections, focusing on two identical rectangular strips on the boundary. In the static case, EWCS increases as the GB coupling constant α increases and disentangles at small separation between two strips for smaller α. For the dynamic case, such a monotonic relationship between EWCS and α holds but the two strips no longer disentangle monotonically as in the static case. In the early thermal quenching stage, the disentanglement occurs at smaller αwith larger separations. Two strips then disentangle at larger separation with larger α as time evolves. Our results indicate that the higher-order derivative corrections, like the entanglement measure in the dual boundary theory, also have nontrivial effects on the EWCS evolution.

Out-of-time-order correlators in the one-dimensional XY model

We study the behavior of information spreading in the XY model, using out-of-time-order correlators(OTOCs). The effects of anisotropic parameter γ and external magnetic field λon OTOCs are studied in detail within thermodynamical limits. The universal form which characterizes the wavefront of information spreading still holds in the XY model. The butterfly speed vBdepends on(γ, λ). At a fixed location, the early-time evolution behavior of OTOCs agrees with the results of the Hausdorff–Baker–Campbell expansion. For long-time evolution,OTOCs with local operators decay as for power law t^-1, but those with nonlocal operators show different and nontrivial power law behaviors. We also observe temperature dependence for OTOCs when(γ=0, λ=1). At low temperature, the OTOCs with nonlocal operators show divergence over time.

Dynamical spontaneous scalarization in Einstein-Maxwell-scalar theory

We study the linear instability and nonlinear dynamical evolution of the Reissner-Nordstrom(RN)black hole in the Einstein-Maxwell-scalar theory in asymptotic flat spacetime.We focus on the coupling function f(φ)=e^(-bφ^(2)),which facilitates both scalar-free RN and scalarized black hole solutions.We first present the evolution of system parameters during dynamic scalarization.For parameter regions in which spontaneous scalarization occurs,we observe that the evolution of the scalar field at the horizon is dominated by the fundamental unstable mode from linear analysis at early times.At late times,the nonlinear evolution can be considered to be the perturbation of scalarized black holes.