Global Energetics of Solar Flares, X. Petschek Reconnection Rate and Alfvén Mach Number of Magnetic Reconnection Outflows 

Markus J. Aschwanden Submitted: 20200507 13:48
We investigate physical scaling laws for magnetic energy dissipation
in solar flares, in the framework of the SweetParker model
and the Petschek model. We find that the total dissipated magnetic energy
E_{diss} in a flare depends on the mean magnetic field component
B_{f} associated with the free energy E_{f}, the length scale L of the
magnetic area, the hydrostatic density scale height lambda of
the solar corona, the Alfvén Mach number M_A=v_1/v_{A} (the ratio
of the inflow speed v_{1} to the Alfvénic outflow speed v_{A}), and the
flare duration au_f, i.e., E_{diss} = (1/4π) B_f^2 L lambda
v_{A} M_A au_f, where the Alfvén speed depends on the nonpotential
field strength B_{np} and the mean electron density n_{e} in the
reconnection outflow. Using MDI/SDO and AIA/SDO observations and
3D magnetic field solutions obtained with the verticalcurrent
approximation nonlinear forcefree field code (VCANLFFF) we measure
all physical parameters necessary to test scaling laws, which
represents a new method to measure Alfvén Mach numbers M_{A},
the reconnection rate, and the total free energy dissipated
in solar flares.
Authors: Markus J. Aschwanden
Projects: SDOHMI

Publication Status: ApJ (in press)
Last Modified: 20200511 15:28


