Self-Similar Evolution of Fast Magnetic Reconnection in Free Space: a
New Model for Astrophysical Reconnection

S. Nitta (Soken-dai), S. Tanuma, K. Shibata, and K. Maezawa

We present a new model for time evolution of the fast magnetic
reconnection in free space, which is characterized by self-similarity.
The possibility of this type of evolution is verified by numerical
simulations. We also find an analytical solution which is consistent
with the numerical result. In many cases of astrophysical problems,
e.g., solar flares or geomagnetospheric substorms, the spatial scale of
the reconnection system significantly expands as time proceeds. The
resultant spatial scale of the reconnection system is much larger than
the initial scale (its dynamic range is typically 7 figures of
magnitude). In spite of this, most previous works focused on the
character of evolution strongly affected by artificial boundary
conditions. The focus of this work is on this expanding phase. Our new
model for magnetic reconnection aims to clarify a realistic evolution
and spontaneous structure formation in free space.