We report on results of imaging and spectral studies of X-ray emission from Jupiter observed by Suzaku .
In 2006 Suzaku had found diffuse X-ray emission in 1–5 keV associated with Jovian inner radiation belts .
It has been suggested that the emission is caused by the inverse-Compton scattering by ultra-relativistic electrons ( \sim 50 MeV ) in Jupiter ’ s magnetosphere .
To confirm the existence of this emission and to understand its relation to the solar activity , we conducted an additional Suzaku observation in 2014 around the maximum of the 24th solar cycle .
As a result , we successfully found again the diffuse emission around Jupiter in 1–5 keV and also point-like emission in 0.4–1 keV .
The luminosity of the point-like emission which was probably composed of solar X-ray scattering , charge exchange , or auroral bremsstrahlung emission increased by a factor of \sim 5 with respect to 2006 , most likely due to an increase of the solar activity .
The diffuse emission spectrum in the 1–5 keV band was well-fitted with a flat power-law function ( \Gamma = 1.4 \pm 0.1 ) as in the past observation , which supported the inverse-Compton scattering hypothesis .
However , its spatial distribution changed from \sim 12 \times 4 Jovian radius ( Rj ) to \sim 20 \times 7 Rj .
The luminosity of the diffuse emission increased by a smaller factor of \sim 3 .
This indicates that the diffuse emission is not simply responding to the solar activity , which is also known to cause little effect on the distribution of high-energy electrons around Jupiter .
Further sensitive study of the spatial and spectral distributions of the diffuse hard X-ray emission is important to understand how high-energy particles are accelerated in Jupiter ’ s magnetosphere .