The shadow and quasinormal modes of the asymptotically flat hairy black holes with a dilaton potential
In this article, the shadow and the quasinormal modes (QNMs) of an exact asymptotically flat hairy electrically charged black hole solution with a dilaton potential are investigated. Using the {constraint} equation among the integration constant $η$ of the gravitational field, the mass $M$, the electric charge $Q$ and the coupling constant $ν$ between the $U(1)$ field and the dilaton field, we find that the shadow radii, the Lyapunov exponent $λ$ and the coordinate angular velocity $Ω_{c}$ only significantly affected by $ν$ if the $Q$ is close to the extremal value, especially when $ν$ approaches to one. Furthermore, the QNMs are numerically computed by using the Hatsuda method and verify with the higher-order WKB approximations with the Padé summation. We find that the QNMs are close to that of the low energy limit of the string theory when $ν$ is large enough. In the eikonal limit, the real and imaginary parts are proved to be given by $Ω_{c}$ and $λ$, respectively.