Hiroyuki R. Takahashi

SCALING LAW OF RELATIVISTIC SWEET-PARKER-TYPE MAGNETIC RECONNECTION

Relativistic Sweet-Parker-type magnetic reconnection is investigated by relativistic resistive magnetohydrodynamic (RRMHD) simulations. As an initial setting, we assume anti-parallel magnetic fields and a spatially uniform resistivity. A perturbation imposed on the magnetic fields triggers magnetic reconnection around a current sheet, and the plasma inflows into the reconnection region. The inflows are then heated due to ohmic dissipation in the diffusion region and finally become relativistically hot outflows. The outflows are not accelerated to ultrarelativistic speeds (i.e., Lorentz factor {approx_equal} 1), even when the magnetic energy dominates the thermal and rest mass energies in the inflow region. Most of the magnetic energy in the inflow region is converted into the thermal energy of the outflow during the reconnection process. The energy conversion from magnetic to thermal energy in the diffusion region results in an increase in the plasma inertia. This prevents the outflows from being accelerated to ultrarelativistic speeds. We find that the reconnection rate R obeys the scaling relation R{approx_equal}S{sup -0.5}, where S is the Lundquist number. This feature is the same as that of non-relativistic reconnection. Our results are consistent with the theoretical predictions of Lyubarsky for Sweet-Parker-type magnetic reconnection.

FORMATION OF OVERHEATED REGIONS AND TRUNCATED DISKS AROUND BLACK HOLES: THREE-DIMENSIONAL GENERAL RELATIVISTIC RADIATION-MAGNETOHYDRODYNAMICS SIMULATIONS

Using three-dimensional general relativistic radiation magnetohydrodynamics simulations of accretion flows around stellar mass black holes, we report that the relatively cold disk (

EXPLICIT-IMPLICIT SCHEME FOR RELATIVISTIC RADIATION HYDRODYNAMICS

\gtrsim 10^{7}

A Numerical Treatment of Anisotropic Radiation Fields Coupled with Relativistic Resistive Magnetofluids

K) is truncated near the black hole. Hot and less-dense regions, of which the gas temperature is

Radiation drag effects in black hole outflows from super-critical accretion disks via special relativistic radiation magnetohydrodynamics simulations

\gtrsim 10^9

Radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows

K and more than ten times higher than the radiation temperature (overheated regions), appear within the truncation radius. The overheated regions also appear above as well as below the disk, and sandwich the cold disk, leading to the effective Compton upscattering. The truncation radius is

Relativistic expansion of magnetic loops at the self‐similar stage – II. Magnetized outflows interacting with the ambient plasma

\sim 30 r_{\rm g}

Relativistic expansion of magnetic loops at the self-similar stage

for

A NUMERICAL SCHEME FOR SPECIAL RELATIVISTIC RADIATION MAGNETOHYDRODYNAMICS BASED ON SOLVING THE TIME-DEPENDENT RADIATIVE TRANSFER EQUATION

\dot{M} \sim L_{\rm Edd}/c^2

Supercritical Accretion onto a Non-magnetized Neutron Star: Why is it Feasible?

, where