21 research outputs found
Hitomi (ASTRO-H) X-ray Astronomy Satellite
The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month
Hitomi X-Ray Studies of Giant Radio Pulses from the Crab Pulsar
To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2300 keV band and the Kashima NICT radio telescope in the 1.41.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 fluctuations of the X-ray fluxes at the pulse peaks, and the 3 upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.510 keV and 70300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) 10(exp 11) erg cm(exp 2), respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a >0.02% brightening of the pulse-peak flux under such conditions
STIX X-ray microflare observations during the Solar Orbiter commissioning phase
The Spectrometer/Telescope for Imaging X-rays (STIX) is the HXR instrument
onboard Solar Orbiter designed to observe solar flares over a broad range of
flare sizes, between 4-150 keV. We report the first STIX observations of
microflares recorded during the instrument commissioning phase in order to
investigate the STIX performance at its detection limit. This first result
paper focuses on the temporal and spectral evolution of STIX microflares
occuring in the AR12765 in June 2020, and compares the STIX measurements with
GOES/XRS, SDO/AIA, and Hinode/XRT. For the observed microflares of the GOES A
and B class, the STIX peak time at lowest energies is located in the impulsive
phase of the flares, well before the GOES peak time. Such a behavior can either
be explained by the higher sensitivity of STIX to higher temperatures compared
to GOES, or due to the existence of a nonthermal component reaching down to low
energies. The interpretation is inconclusive due to limited counting statistics
for all but the largest flare in our sample. For this largest flare, the
low-energy peak time is clearly due to thermal emission, and the nonthermal
component seen at higher energies occurs even earlier. This suggests that the
classic thermal explanation might also be favored for the majority of the
smaller flares. In combination with EUV and SXR observations, STIX corroborates
earlier findings that an isothermal assumption is of limited validity. Future
diagnostic efforts should focus on multi-wavelength studies to derive
differential emission measure distributions over a wide range of temperatures
to accurately describe the energetics of solar flares. Commissioning
observations confirm that STIX is working as designed. As a rule of thumb, STIX
detects flares as small as the GOES A class. For flares above the GOES B class,
detailed spectral and imaging analyses can be performed.Comment: 19 pages, 11 figure
Distinctive Features of NREM Parasomnia Behaviors in Parkinson’s Disease and Multiple System Atrophy
Cryptococcus neoformans Infections Differ Among Human Immunodeficiency Virus (HIV)–Seropositive and HIV-Seronegative Individuals: Results From a Nationwide Surveillance Program in France
International audienceAmong 1107 cryptococcosis cases from the French surveillance network (2005–2020), the proportion of HIV-seronegative individuals has recently surpassed that of HIV-seropositive individuals. We observed marked differences in patient characteristics, disease presentations, cryptococcal antigen results, infecting species, and mortality according to HIV serostatus
The spectrometer telescope for imaging x-rays on board the Solar Orbiter mission
International audienc
The spectrometer telescope for imaging x-rays on board the Solar Orbiter mission
International audienc