Oblique Tearing Mode Instability: Guide Field and Hall Effect

The tearing mode instability is one important mechanism that may explain the triggering of fast magnetic reconnection in astrophysical plasmas, such as the solar corona and the Earth's magnetosphere. In this paper, the linear stability analysis of the tearing mode is carried out for a current sheet in the presence of a guide field, including the Hall effect. We show that the presence of a strong guide field does not modify the most unstable mode in the 2D wavevector space orthogonal to the current gradient direction, which remains the fastest-growing parallel mode. With the Hall effect, the inclusion of a guide field turns the nondispersive propagation along the guide field direction to a dispersive one. The oblique modes have a wavelike structure along the normal direction of the current sheet and a strong guide field suppresses this structure while making the eigenfunctions asymmetric.