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We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and in microwaves. We analyzed 12 flares observed by the Hard X-ray Telescope aboard {it Yohkoh}, Nobeyama Radio Polarimeters (NoRP), and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of hard X-rays and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap $Deltadelta$ between the electron spectral indices derived from hard X-rays $delta_{X}$ and those from microwaves $delta_{mu}$ ($Deltadelta = delta_{X} - delta_{mu}$) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index $delta_{X}$ evolve synchronously with those of the microwave spectral index $delta_{mu}$, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index $delta_{mu}$ tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.
We investigate the type III radio bursts and X-ray signatures of accelerated electrons in a well observed solar flare in order to find the spatial properties of the acceleration region. Combining simultaneous RHESSI hard X-ray flare data and radio da
We report the detection of hard X-ray emission from the field of the star-forming region NGC 6334 with the the International Gamma-Ray Astrophysics Laboratory INTEGRAL. The JEM-X monitor and ISGRI imager aboard INTEGRAL and Chandra ACIS imager were u
The recent discovery of impulsive solar burst emission in the 30 THz band is raising new interpretation challenges. One event associated with a GOES M2 class flare has been observed simultaneously in microwaves, H-alpha, EUV, and soft X-ray bands. Al
We perform multi-dimensional, time-dependent radiation transfer simulations for hard X-ray and gamma-ray emissions, following radioactive decays of 56Ni and 56Co, for two-dimensional delayed detonation models of Type Ia supernovae (SNe Ia). The synth
The nearest accreting T Tauri star, TW Hya was observed with spectroscopic and photometric measurements simultaneous with a long se gmented exposure using the CHANDRA satellite. Contemporaneous optical photometry from WASP-S indicates a 4.74 day peri