Suzaku Observations of M82 X-1 : Detection of a Curved Hard X-ray Spectrum

A report is presented on Suzaku observations of the ultra-luminous X-ray source X-1 in the starburst galaxy M82, made three time in 2005 October for an exposure of ~ 30 ks each. The XIS signals from a region of radius 3 around the nucleus defined a 2-10 keV flux of 2.1 x 10^-11 erg s-1 cm-2 attributable to point sources. The 3.2-10 keV spectrum was slightly more convex than a power-law with a photon index of 1.7. In all observations, the HXD also detected signals from M82 up to ~ 20 keV, at a 12-20 keV flux of 4.4 x 10^-12 erg s-1 cm-2 . The HXD spectrum was steeper than that of the XIS. The XIS and HXD spectra can be jointly reproduced by a cutoff power-law model, or similar curved models. Of the detected wide-band signals, 1/3 to 2/3 are attributable to X-1, while the remainder to other discrete sources in M82. Regardless of the modeling of these contaminants, the spectrum attributable to X-1 is more curved than a power-law, with a bolometric luminosity of (1.5 -3) x 10 ^40 erg s-1. These results are interpreted as Comptonized emission from a black hole of 100-200 solar masses, radiating roughly at the Eddington luminosity.Comment: 19 pages, 9 figures, accepted in Publications of the Astronomical Society of Japa

Regional Inequality Simulations Based on Asset Exchange Models with Exchange Range and Local Support Bias

To gain insights into the problem of regional inequality, we proposed new regional asset exchange models based on existing kinetic income-exchange models in economic physics. We did this by setting the spatial exchange range and adding bias to asset fraction probability in equivalent exchanges. Simulations of asset distribution and Gini coefficients showed that suppressing regional inequality requires, firstly an increase in the intra-regional economic circulation rate, and secondly the narrowing down of the exchange range (inter-regional economic zone). However, avoiding over-concentration of assets due to repeat exchanges requires adding a third measure; the local support bias (distribution norm). A comprehensive solution incorporating these three measures enabled shifting the asset distribution from over-concentration to exponential distribution and eventually approaching the normal distribution, reducing the Gini coefficient further. Going forward, we will expand these models by setting production capacity based on assets, path dependency on two-dimensional space, bias according to disparity, and verify measures to reduce regional inequality in actual communities.Comment: 14 pages, 8 figures. Published online at http://redfame.com/journal/index.php/aef/article/view/494

Development of Rotary Compressor for High-efficiency CO2 Heat-pump Hot-Water Supply System

In Japan, there has been an increase in the use of domestic heat-pump hot-water supply systems in which the refrigerant is CO2, which does not cause ozone layer depletion and has a low global-warming potential. In addition, in recent years, there has been an increase in the number of examples in which CO2 is employed as a refrigerant for showcase refrigerators, freezers etc. Therefore, in the future, it is expected that there will be an increasing demand for CO2 compressors with greater efficiency and lower noise. In the case of domestic heat-pump hot-water supply systems, in order to increase the annual performance factor (APF) of a product, it is effective to enhance the coefficient of performance (COP) in an intermediate capacity range. Here, we report the development of a high-APF rotary compressor achieved by optimizing the design specifications of a motor and a discharge pathway from a discharge chamber, for operation in the intermediate capacity range. In the optimization process, in order to cope with the high operating pressure of the CO2 water-heating cycle, we performed analysis using the finite element method (FEM) for evaluating the stiffness around the discharge port. In addition, we used an FEM model of the entire compressor in a modal analysis, and, in analyzing the radiation surfaces of the rotary compressor, we used an acoustic particle velocity probe that is capable of measuring the intensity at an intermediate portion between the accumulator and the compressor main unit, where it has been difficult to take measurements in the past. We also discuss an example in which noise reduction was confirmed when the specifications of the accumulator were changed based on the results of these analyses