J-GLOBAL ID:200904029336114737  Research Project code:0450021598 Update date:Jan. 19, 2004

Study on galactic halo

Study period:2002 - 2002
Organization (1):
Investigating Researcher (3):
Research overview:
It is well known that there exists high temperature halo in ellipsoid galaxy but study on the high temperature halo in spiral galaxy such as ours is still on the way. However, if supernova explosion solely supplies energy and materials to high temperature halo, elucidation of the physical state of high temperature halo is an important problem leading to the understanding of material and energy circulation and chemical progress in galaxy. We performed observation of near small size spiral galaxy NGC55 by 'Chandra'. We could determine physical quantities with high precision not obtained before by clarifying the X-ray radiation with low surface brightness around NGC55 by systematic analysis and subtraction of the background. At first, since the peak of X-ray radiation extended in the galaxy surface coincided with the domain of star formation showing shell structure, the possibility that the energy source of halo is supernova explosion is strongly suggested. The hot halo, which extended to 2kpc from galaxy surface, had the temperature of about two million degrees and is thought to blow out of galaxy surface. This gas is not restrained by the gravity of the galaxy and escapes to intergalactic space. Due to the escape of the gas, the amount of heavy elements in hot halo of the galaxy is about 1/10 of solar composition and the ratio of elements is near type 2 supernovas. In future observation, it will be required to elucidate quantitatively the difference in the recycling process of heavy elements in the formation process of galactic wind and star depending on the scale, kind and environment of galaxy.

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