Masanobu Ozaki

Framework for a Geant4-based simulator of the radiation background and detector responses of the space X-ray observatory Suzaku (Astro-E2)

We have constructed a Monte Carlo simulation base for the radiation environment of the Suzaku X-ray observatory satellite. The system consists of an object-oriented analysis framework used for real-data analysis, the Geant4 toolkit, an interface that allows the users a transparent usage of Geant4 components through the framework and classes that are used to build the simulation by a collaboration among different geometry maintainer and detector developer groups. As a demonstration, the geometry of the Hard X-ray Detector, which is one of the Suzaku detectors, is constructed using the framework and a comparison between the simulation output with the actual data is shown.

An X-Ray Counterpart of HESS J1427-608 Discovered with Suzaku

We report the discovery of an X-ray counterpart of the unidentified very high energy gamma-ray source HESS J1427-608. In the sky field coincident with HESS J1427-608, an extended source was found in the 2-8 keV band, and was designated as Suzaku J1427-6051. Its X-ray radial profile has an extension of sigma=0.9 +/- 0.1 if approximated by a Gaussian. The spectrum was well fitted by an absorbed power-law with N_H=(1.1 +/- 0.3) times 10^23 cm^-2, Gamma=3.1 +0.6/-0.5, and the unabsorbed flux F_X=(9 +4/-2) times 10^-13 erg s^-1 cm^-2 in the 2-10 keV band. Using XMM-Newton archive data, we found seven point sources in the Suzaku source region. However, because their total flux and absorbing column densities are more than an order of magnitude lower than those of Suzaku J1427-6051, we consider that they are unrelated to the Suzaku source. Thus, Suzaku J1427-6051 is considered to be a truly diffuse source and an X-ray counterpart of HESS J1427-608. The possible nature of HESS J1427-608 is discussed based on the observational properties.

Radiation physics simulator for space X-ray observatory Astro-E2

We constructed a Monte-Carlo simulator framework for the radiation environment of Astro-E2, the Japanese 5th X-ray astronomy satellite. We used Geant4 as the simulator engine, and embedded it into the analysis framework derived from what has been used for other Astro-E2 software development. The entire architecture is designed to make the learning cost of the framework programming as low as possible for not only end users but developers, and we implemented some software mechanisms to register Geant4 components such as physics processes and geometry builder into the framework without using the Geant4s run manager explicitly.

High-speed on-board data processing for x-ray CCD camera

We have developed a novel architecture to process 2-dimensional digital image data with very high speed. The architecture is realized with an FPGA to extract only the X-ray signals from the raw frame data of an X-ray CCD for an astronomical use. The circuit scale is small enough to be implemented in an FPGA currently available for a space use, while the data processing speed of 107 pixels/sec is achieved. The architecture can be adapted in principle to a wide range of applications.