X-ray Observation of Mars with Suzaku at Solar Minimun

Mars was observed in X-rays during April 3-5 2008 for 82 ksec with the Japanese Suzaku observatory. Mars has been known to emit X-rays via the scattering of solar X-rays and via the charge exchange between neutral atoms in the exosphere and solar wind ions. Past theoretical studies suggest that the exospheric neutral density may vary by a factor of up to 10 over the solar cycle. To investigate a potential change of the exospheric charge exchange emission, Mars was observed with Suzaku at solar minimum. Significant signals were not detected at the position of Mars in the energy band of 0.2-5 keV. A 2 sigma upper limit of the O VII line flux in 0.5-0.65 keV was 4.3$\times10^{-5}$ ph cm$^{-2}$ s$^{-1}$. Comparing this upper limit to the past Chandra and XMM-Newton observations conducted near solar maximum, it was found that the exospheric density at solar minimum does not exceed that near solar maximum by more than 6-70 times.Comment: 17 pages, 7 figures, accepted for publication in PAS

Modeling of geocoronal solar wind charge exchange events detected with Suzaku

A model of geocoronal solar wind charge exchange (SWCX) emission was built and compared to five Suzaku detections of bright geocoronal SWCX events. An exospheric neutral hydrogen distribution model, charge exchange cross sections, solar wind ion data taken with the ACE and WIND satellites, and magnetic field models of the Earth's magnetosphere are all combined in order to predict time-variable geocoronal SWCX emission depending on line-of-sight directions of the Suzaku satellite. The modeled average intensities of O VII emission lines were consistent with the observed ones within a factor of three in four out of the five cases except for an event in which a line-of-sight direction was toward the night side of the high-latitude magnetosheath and a major geomagnetic storm was observed. Those of O VIII emission lines were underestimated by a factor of three or more in all the five cases. On the other hand, the modeled O VII and O VIII light curves reproduced the observed ones after being scaled by ratios between the observed and modeled average intensities. In particular, short-term variations due to line-of-sight directions traversing cusp regions during an orbital motion of the Suzaku satellite were reproduced. These results are discussed in the context of model uncertainties.Comment: 47 pages, 23 figures, accepted for publication in PAS

Oil-in-water emulsion lotion providing controlled release using 2-methacryloyloxyethyl phosphorylcholine n-butyl methacrylate copolymer as emulsifier

AbstractLotion is a useful vehicle for active ingredients used to treat skin disease because it can be applied to the scalp, can cover large areas of skin, and it is easy to spread due to low viscosity. An emulsion lotion (EL) containing 2-methacryloyloxyethyl phosphorylcholine n-butyl methacrylate copolymer (PMB) as an emulsifier that provides controlled-release was developed. Diphenhydramine (DPH) was used as a model drug. Formulation with 5% DPH, 5% soybean oil, and 4% PMB in water was emulsified using a high-pressure homogenizer. Polysorbate 80 (TO) was used instead of PMB for comparison. They were applied in vitro to Yucatan micropig intact or stripped skin at a practical dose (2μL/cm2). For stripped skin, penetration of DPH from 4% PMB EL was slower than that from 1% TO EL; results for intact skin were similar. The same phenomenon was observed with application to rabbit skin in vivo. When 4% PMB EL dried on the skin, it made a thin film matrix incorporating the oil phase, which controlled the release of DPH. The release rate could be controlled by the ratio of oil phase to PMB. The EL with PMB shows promise as a vehicle for long-acting treatment of skin diseases

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

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\unicode{x2013}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\unicode{x2013}5 keV and also point-like emission in 0.4\unicode{x2013}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\unicode{x2013}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.Comment: 17 pages, 4 figures, 1 tabl

The Quiescent Intracluster Medium in the Core of the Perseus Cluster

Clusters of galaxies are the most massive gravitationally-bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and a host of astrophysical processes. Knowledge of the dynamics of the pervasive hot gas, which dominates in mass over stars in a cluster, is a crucial missing ingredient. It can enable new insights into mechanical energy injection by the central supermassive black hole and the use of hydrostatic equilibrium for the determination of cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50 million K diffuse hot plasma filling its gravitational potential well. The Active Galactic Nucleus of the central galaxy NGC1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These likely induce motions in the intracluster medium and heat the inner gas preventing runaway radiative cooling; a process known as Active Galactic Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus cluster core, which reveal a remarkably quiescent atmosphere where the gas has a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s is found across the 60 kpc image of the cluster core. Turbulent pressure support in the gas is 4% or less of the thermodynamic pressure, with large scale shear at most doubling that estimate. We infer that total cluster masses determined from hydrostatic equilibrium in the central regions need little correction for turbulent pressure.Comment: 31 pages, 11 Figs, published in Nature July

Porous Plug Phase Separator and Superfluid Film Flow Suppression System for the Soft X-Ray Spectrometer Onboard Hitomi

When using superfluid helium in low gravity environments, porous plug phase separators are commonly used to vent boiloff gas while confining the bulk liquid to the tank. Invariably, there is a flow of superfluid film from the perimeter of the porous plug down the vent line. For the Soft X-ray Spectrometer onboard ASTRO-H (Hitomi), its approximately 30-liter helium supply has a lifetime requirement of more than 3 years. A nominal vent rate is estimated as ~ 30 ug/s, equivalent to ~ 0.7 mW heat load. It is therefore critical to suppress any film flow whose evaporation would not provide direct cooling of the remaining liquid helium. That is, the porous plug vent system must be designed to both minimize film flow and to ensure maximum extraction of latent heat from the film. The design goal for Hitomi is to reduce the film flow losses to <2 ug/s, corresponding to a loss of cooling capacity of <40 uW. The design adopts the same general design as implemented for Astro-E and E2, using a vent system composed of a porous plug, combined with an orifice, a heat exchanger, and knife-edge devices. In this paper, design, on-ground testing results and in-orbit performance are described

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