J 2023

Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic expansion

ČEMELJIĆ, Miljenko, Wlodzimierz KLUŹNIAK a V. PARTHASARATHY

Základní údaje

Originální název

Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic expansion

Autoři

ČEMELJIĆ, Miljenko (191 Chorvatsko, domácí), Wlodzimierz KLUŹNIAK (616 Polsko, domácí) a V. PARTHASARATHY

Vydání

ASTRONOMY & ASTROPHYSICS, LES ULIS CEDEX A, EDP SCIENCES S A, 2023, 0004-6361

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10308 Astronomy

Stát vydavatele

Francie

Utajení

není předmětem státního či obchodního tajemství

Odkazy

Kód RIV

RIV/47813059:19630/23:A0000263

Organizační jednotka

Fyzikální ústav v Opavě

UT WoS

001142864300001

Klíčová slova anglicky

accretion;accretion disks;magnetohydrodynamics (MHD);methods: analytical;methods: numerical;stars: neutron;X-rays: binaries

Štítky

Příznaky

Mezinárodní význam, Recenzováno

Návaznosti

GX21-06825X, projekt VaV.
Změněno: 14. 2. 2024 11:49, Mgr. Pavlína Jalůvková

Anotace

V originále

Aims. A realistic model of magnetic linkage between a central object and its accretion disk is a prerequisite for understanding the spin history of stars and stellar remnants. To this end, we aim to provide an analytic model in agreement with magnetohydrodynamic (MHD) simulations.Methods. For the first time, we wrote a full set of stationary asymptotic expansion equations of a thin magnetic accretion disk, including the induction and energy equations. We also performed a resistive MHD simulation of an accretion disk around a star endowed with a magnetic dipole, using the publicly available code PLUTO. We compared the analytical results with the numerical solutions, and discussed the results in the context of previous solutions of the induction equation describing the star-disk magnetospheric interaction.Results. We found that the magnetic field threading the disk is suppressed by orders of magnitude inside thin disks, so the presence of the stellar magnetic field does not strongly affect the velocity field, nor the density profile inside the disk. Density and velocity fields found in the MHD simulations match the radial and vertical profiles of the analytic solution. Qualitatively, the MHD simulations result in an internal magnetic field similar to the solutions previously obtained by solving the induction equation in the disk alone. However, the magnetic field configuration is quantitatively affected by magnetic field inflation outside the disk; this is reflected in the net torque. The torque on the star is an order of magnitude larger in the magnetic than in the non-magnetic case. Spin-up of the star occurs on a timescale comparable to the accretion timescale in the MHD case, and is an order of magnitude slower in the absence of a stellar magnetic field.