Magneto-rotational instability in magnetically polarized discs

The magneto-rotational instability (MRI) is the most likely mechanism for transportation of angular momentum and dissipation energy within hot, ionized accretion discs. This produced through interactions a differentially rotating plasma with an embedded magnetic field. Like all substances in nature, disc has potential to become magnetically polarized when it interacts In this paper, we study effect susceptibility, parameterized by $\chi_m$, on MRI, specifically context black hole accretion. We find from linear analysis Newtonian limit that minimum wavelength first unstable mode fastest growing are shorter paramagnetic ($\chi_m>0$) than diamagnetic ($\chi_m<0$) discs, other parameters being equal. Furthermore, magnetization parameter (ratio gas pressure) saturated state should be smaller susceptibility positive negative. confirm latter prediction set numerical simulations additionally vertically integrated stress mass rate somewhat larger diamagnetic. If astrophysical discs able any significant degree, then our results would relevant properly interpreting observations.