Decay of massive scalar field in a black hole background immersed in magnetic field

We evaluate quasinormal modes of massive scalar field of the Ernst spacetime, an exact solution of the Einstein-Maxwell equations describing a black hole immersed in uniform magnetic field $B$. It is known that the quasinormal spectrum for massive scalar field in the vicinity of the magnetized black holes acquires an effective mass ${\mu }_{eff}=\sqrt{4B^2{m}^2+{\mu }^2}$, where $m$ is the azimuthal number and $\mu$ is the mass of scalar field. The numerical result shows that increasing of the field effective mass and the magnetic field $B$ gives rise to decreasing of the imaginary part of the quasinormal modes until reaching the vanishing damping rate.