Spontaneous scalarization of regular Hayward black holes in Einstein-nonlinear electromagnetic-scalar gravity

Abstract

In this paper, we discuss the spontaneous scalarization of Hayward black holes in Einstein-nonlinear electromagnetic-scalar gravity. Taking into account the tachyonic instability, we obtain scalarized charged black holes (SCBHs) with quadratic (1-$\alpha\varphi^2$) and exponential ($e^{-\alpha \varphi^2}$) couplings, respectively. Moreover, these SCBHs can be labelled by the number of $n = 0, 1, 2,...$, where $n = 0$ is called the fundamental black hole and $n = 1, 2,...$ denote the $n$-excited black holes. We recover that the $n = 0$ branch for both couplings is stable against radial perturbations. This stability shows that this branch can be used for further observational implications.