  Magnetic reconnection is a process whereby magnetic field lines in different
directions "reconnect" with each other, resulting in the rearrangement of
magnetic field topology together with the conversion of magnetic field energy
into the kinetic energy (K.E.) of energetic particles. This process occurs in
magnetized astronomical plasmas, such as those in the solar corona, Earth's
magnetosphere, and active galactic nuclei, and accounts for various phenomena,
such as solar flares, energetic particle acceleration, and powering of photon
emission. In the present study, we report the experimental demonstration of
magnetic reconnection under relativistic electron magnetization situation,
along with the observation of power-law distributed outflow in both electron
and proton energy spectra. Through irradiation of an intense laser on a
"micro-coil", relativistically magnetized plasma was produced and magnetic
reconnection was performed with maximum magnetic field 3 kT. In the downstream
outflow direction, the non-thermal component is observed in the high-energy
part of both electron and proton spectra, with a significantly harder power-law
slope of the electron spectrum (p = 1.535 +/- 0.015) that is similar to the
electron injection model proposed to explain a hard emission tail of Cygnus
X-1, a galactic X-ray source with the same order of magnetization. The obtained
result showed experimentally that the magnetization condition in the emitting
region of a galactic X-ray source is sufficient to build a hard electron
population through magnetic reconnection.
