We report the unambiguous detection of non-thermal X-ray emission up to 30 Â keV from the Cannonball , a few-arcsecond long diffuse X-ray feature near the Galactic Center , using the NuSTAR Â X-ray observatory .
The Cannonball is a high-velocity ( v _ { proj } \sim 500  km s ^ { -1 } ) pulsar candidate with a cometary pulsar wind nebula ( PWN ) located \sim 2 ^ { \prime } north-east from Sgr A* , just outside the radio shell of the supernova remnant Sagittarius A ( Sgr A ) East .
Its non-thermal X-ray spectrum , measured up to 30  keV , is well characterized by a \Gamma \sim 1.6 power-law , typical of a PWN , and has an X-ray luminosity of L ( 3 - 30 { keV } ) = 1.3 \times 10 ^ { 34 }  erg s ^ { -1 } .
The spectral and spatial results derived from X-ray and radio data strongly suggest a runaway neutron star born in the Sgr A East supernova event .
We do not find any pulsed signal from the Cannonball .
The NuSTAR Â observations allow us to deduce the PWN magnetic field and show that it is consistent with the lower limit obtained from radio observations .