English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We investigate the density-shear instability in Hall-MHD via numericalsimulation of the full non-linear problem, in the context of magnetar activity.We confirm the development of the instability of a plane-parallel magneticfield with an appropriate intensity and electron density profile, in accordancewith analytic theory. We find that the instability also appears for amonotonically decreasing electron number density and magnetic field, aplane-parallel analogue of an azimuthal or meridional magnetic field in thecrust of a magnetar. The growth rate of the instability depends on the Hallproperties of the field (magnetic field intensity, electron number density andthe corresponding scale-heights), while being insensitive to weak resistivity.Since the Hall effect is the driving process for the evolution of the crustalmagnetic field of magnetars, we argue that this instability is critical forsystems containing strong meridional or azimuthal fields. We find that thisprocess mediates the formation of localised structures with much strongermagnetic field than the average, which can lead to magnetar activity andaccelerate the dissipation of the field and consequently the production ofOhmic heating. Assuming a $5\times10^{14}$G magnetic field at the base ofcrust, we anticipate that magnetic field as strong as $10^{15}$G will easilydevelop in regions of typical size of a few $10^{2}$ meters, containingmagnetic energy of $10^{43}$erg, sufficient to power magnetar bursts. Theseactive regions are more likely to appear in the magnetic equator where thetangential magnetic field is stronger.

Magnetar Activity via the Density-Shear Instability in Hall-MHD