A global model of the magnetorotational instability in proto-neutron stars

Alexis Reboul-Salze (1, 2) , Jérôme Guilet (1, 2) , Raphaël Raynaud (1, 2) , Matteo Bugli (1, 2)

1 DAP - Département d'Astrophysique (ex SAP)
2 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation

The magnetorotational instability (MRI) is a promising mechanism to amplify the magnetic field in fast-rotating proto-neutron stars. Many local studies have shown that the magnetic field could be amplified on small scales. However, the efficiency of the MRI at generating a large-scale field similar to the dipolar magnetic field of magnetars (10 14 − 10 15 G) is still unknown. We used a three dimensional pseudo-spectral code to develop an idealized global model of the MRI in a proto-neutron star. We show that a dipole field strength consistent with the values of magnetar field intensity can be generated by the MRI, even though it is lower than the small-scale magnetic field. Overall, our results support the ability of the MRI to form magnetar-like dipolar magnetic fields.

Mots clés: magnetars; supernovae; magnetohydrodynamics (MHD); instabilities; methods: numerical

Domaines: Astrophysique [astro-ph]; Phénomènes cosmiques de haute energie [astro-ph.HE]; Astrophysique stellaire et solaire [astro-ph.SR]

Alexis Reboul-Salze, Jérôme Guilet, Raphaël Raynaud, Matteo Bugli. A global model of the magnetorotational instability in proto-neutron stars. Journées de la SF2A, Société Francaise d’Astronomie et d’Astrophysique, May 2019, Nice, France. ⟨hal-02428439⟩