Quasinormal modes in the field of a dyon-like dilatonic black hole

Quasinormal modes of massless test scalar field in the background of gravitational field for a non-extremal dilatonic dyonic black hole are explored. The dyon-like black hole solution is considered in the gravitational 4d model involving two scalar fields and two 2-forms. It is governed by two 2-dimensional dilatonic coupling vectors $${\lambda }_i$$ λ i obeying $${\lambda }_i ({\lambda }_1 + {\lambda }_2) > 0$$ λ i ( λ 1 + λ 2 ) > 0 , $$i =1,2$$ i = 1 , 2 . The first law of black hole thermodynamics is given and the Smarr relation is verified. Quasinormal modes for a massless scalar (test) field in the eikonal approximation are obtained and analysed. These modes depend upon a dimensionless parameter a ($$0 < a \le 2$$ 0 < a ≤ 2 ) which is a function of $${\lambda }_i$$ λ i . For limiting strong ($$a = +0$$ a = + 0 ) and weak ($$a = 2$$ a = 2 ) coupling cases, they coincide with the well-known results for the Schwarzschild and Reissner–Nordström solutions. It is shown that the Hod conjecture, connecting the damping rate and the Hawking temperature, is satisfied for $$0 < a \le 1$$ 0 < a ≤ 1 and all allowed values of parameters.

Dilatonic dyon black hole solutions in the model with two Abelian gauge fields

Dilatonic black hole dyon-like solutions in the gravitational 4d model with a scalar field, two 2-forms, two dilatonic coupling constants λi ≠ 0, i = 1,2, obeying λ1 ≠ − λ2 and sign parameter ε = ±1 for scalar field kinetic term are considered. Here ε = −1 corresponds to ghost scalar field. These solutions are defined up to solutions of two master equations for two moduli functions, when λi2 ≠ 1/2 for ε = −1. A set of bounds on gravitational mass and scalar charge are presented by using a certain conjecture on parameters of solutions, when 1 + 2λi2ε > 0, i = 1, 2.

DIPOLE COUPLING EFFECT OF HOLOGRAPHIC FERMION IN CHARGED DILATONIC GRAVITY

In this note, we study the dipole coupling effect of holographic fermion in a charged dilatonic black hole proposed by Gubser and Rocha.1 It is found that the property of Fermi liquid is rigid under perturbation of dipole coupling, and the Fermi momentum is linearly shifted. A gap is dynamically generated as the coupling becomes large enough and the Fermi surface ceases to exist as the bulk dipole coupling further increases.