Suzaku observation of Jupiter's X-rays around solar maximum

Masaki Numazawa, Yuichiro Ezoe, Kumi Ishikawa, Takaya Ohashi, Yoshizumi Miyoshi, Tomoki Kimura, Yasunobu Uchiyama, Daikou Shiota, Graziella Branduardi-Raymont

研究成果: Article査読


We report on results of imaging and spectral studies of X-ray emission from Jupiter observed by Suzaku. In 2006, Suzaku 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 (∼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 the diffuse emission around Jupiter in 1-5 keV again, and also found 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 ∼5 with respect to the findings from 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 (Γ = 1.4 ± 0.1) as in the past observation, which supported the inverse-Compton scattering hypothesis. However, its spatial distribution changed from ∼12 × 4 Jovian radius (Rj) to ∼20 × 7 Rj. The luminosity of the diffuse emission increased by the smaller factor of ∼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.

ジャーナルPublications of the Astronomical Society of Japan
出版ステータスPublished - 2019 10 1

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学


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