Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic ...

@article{77162,
   author = {Čemeljić, Miljenko and Kluźniak, Wlodzimierz and Parthasarathy, V.},
   article_location = {LES ULIS CEDEX A},
   article_number = {Oct 2023},
   doi = {http://dx.doi.org/10.1051/0004-6361/202140637},
   keywords = {accretion;accretion disks;magnetohydrodynamics (MHD);methods: analytical;methods: numerical;stars: neutron;X-rays: binaries},
   language = {eng},
   issn = {0004-6361},
   journal = {ASTRONOMY & ASTROPHYSICS},
   title = {Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic expansion},
   url = {https://www.aanda.org/articles/aa/full_html/2023/10/aa40637-21/aa40637-21.html},
   volume = {678},
   year = {2023}
}

TY  - JOUR
ID  - 77162
AU  - Čemeljić, Miljenko - Kluźniak, Wlodzimierz - Parthasarathy, V.
PY  - 2023
TI  - Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic expansion
JF  - ASTRONOMY & ASTROPHYSICS
VL  - 678
IS  - Oct 2023
SP  - "A57-1"-"A57-16"
EP  - "A57-1"-"A57-16"
PB  - EDP SCIENCES S A
SN  - 00046361
KW  - accretion;accretion disks;magnetohydrodynamics (MHD);methods: analytical;methods: numerical;stars: neutron;X-rays: binaries
UR  - https://www.aanda.org/articles/aa/full_html/2023/10/aa40637-21/aa40637-21.html
N2  - 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.
ER  - 

ČEMELJI$\backslash$'C, Miljenko, Wlodzimierz KLU$\backslash$'ZNIAK and V. PARTHASARATHY. Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic expansion. \textit{ASTRONOMY \&{}amp; ASTROPHYSICS}. LES ULIS CEDEX A: EDP SCIENCES S A, 2023, vol.~678, Oct 2023, p.~''A57-1''-''A57-16'', 16 pp. ISSN~0004-6361. Available from: https://dx.doi.org/10.1051/0004-6361/202140637.