It is thought that a huge black hole at the center of a galaxy releases energy to heat the surrounding gas. Continuous X-ray emissions need a heat source, and one of the possibilities is the heavy mass of a black hole. But at the center of a galaxy cluster, X-ray emissions continue. Normally, when energy is released, a gas should cool down and stop emitting X-rays. Meanwhile, because the gas density in a galaxy cluster is extremely high, X-ray radiation releases very strong energy. A black hole has such strong gravity that it sucks in anything around it, but at the same time, it provides very high energy to areas around it. We captured very high-energy gas shooting out from this black hole. At the center of this galaxy cluster, there is a big galaxy known as M87, and in its center is an enormous black hole about 100 million times the mass of the Sun. As for my major achievement to date, my research on the Virgo galaxy cluster using the European X-ray astronomy satellite XMM-Newton stands out. In conjunction with that, I research black holes located at the center of galaxies. My major research topic is the formation of galaxies and galaxy clusters. What is your research specialty? Tell us about your major research achievement? It still remains a mystery how such an enormous black hole can be generated. At this point, a black hole has a mass about 10 times greater than the Sun.Īnother kind is an enormous black hole with a mass that is millions, or even several hundred million times greater than that of the Sun. When a massive star with more than 30 times the mass of the Sun finishes its life, a supernova explosion occurs, and the center of the star becomes unable to withstand its own gravity, shrinking to the utmost limit to become a black hole. One type is generated after a supernova explosion. To date, two kinds of black holes have been observed. Most galaxies have a black hole at their center. This proves the existence of a black hole.
But when gases are sucked into a black hole, they reach ultra-high temperatures and release a lot of energy, flashing brightly in the X-ray spectrum. Thus, we cannot observe black holes directly. Even light cannot escape its gravitational field, so a black hole itself doesn’t release light. Belsole, Service d'Astrophysique, CEA Saclay, France)Ī black hole is a celestial object that has very high density and a strong gravitational field. Two lines of radio-wave jets stretching left and below overlap with X-ray jets. (Bottom) X-ray jets, indicated in white, superimposed over a radio map of the galaxy. (Top Right) Image of a black hole with X-ray jets extracted from the top left photo. (Top Left) Virgo galaxy cluster observed by XMM-Newton. Brighter black holes can be observed in other wavelengths, such as optical light and infrared rays, so I think it is important to combine these in observations. In particular, darker black holes can only be found using X-rays. The areas around black holes have very high energy, so they can be observed very well with X-rays. Are X-rays suited to the observation of black holes? We need to see various aspects of the universe in various wavelengths, but I am personally interested in high-energy phenomena, so X-rays are perfect for me. A star emitting optical light is very beautiful, and it’s an important component of the universe as well, but to understand everything about the universe, we have to look at things apart from stars. X-rays provide us with a lot of information, and what is particularly interesting to me is that this includes information about most of the universe. This light can let us see various astronomical phenomena that can’t be seen with optical light – that’s the attraction for me. X-rays are light that is invisible to the human eye. (courtesy: NASA/CXC/MIT/F.K.Baganoff et al.) Red indicates low energy and blue indicates high energy. The gas spreading toward the top right and left from the center looks red. The center of the Milky Way galaxy viewed with X-rays.
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