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X-ray Astronomy at JAXA Japan's Leading-Edge X-ray Astronomy: Unveiling the Mysteries of a Dynamic Universe
Japan's World-Leading X-ray Astronomy
ASCA Leads the World in X-ray Astronomy

ASCA, which was launched by Japan in 1993, was the first satellite to record X-ray images and disperse X-rays at the same time. This was a great achievement in X-ray spectroscopy, a previously undeveloped area. It was the result of close collaboration with U.S. scientists and support from NASA, as well as outstanding instruments developed in Japan.

The international collaboration went beyond building instruments, though. Observation time was distributed to foreign researchers, with 10 per cent assigned to Europe and the rest shared between Japan and the United States. Furthermore, all the accumulated data is now made available to scientists around the world. This has dramatically increased our overseas collaborations, and Japan has become the international center for X-ray astronomy research.

It is not an exaggeration to say that Japan's ASCA satellite made significant contributions to the advancement of X-ray astronomy in the 1990s, alongside the German satellite ROSAT. Back then, all researchers in the world relied on ASCA and ROSAT because neither NASA nor ESA had a substantial X-ray observatory.

It is not easy to summarize ASCA's achievements, since its observations have produced close to 3,000 published papers. However, even though they are rather technical, let me list some of its major discoveries:

1) Broad iron lines proving that the active nucleus of a galaxy is a super-massive black hole
2) Analysis of the elemental composition, heterogeneity and particle acceleration of supernova remnants by dispersing X-rays
3) X-ray emissions from a newly-formed protostar
4) A two-temperature structure of hot plasma in a galaxy cluster

In addition, many of the major objectives of two large X-ray astronomy satellites that are currently functioning, NASA's Chandra and ESA's XMM-Newton, stem from themes developed by ASCA.

Plans for SUZAKU (ASTRO-EII)
 

ASTRO-EII IllustrationThe launch of ASTRO-E failed in 2000, or it would have been one of the three major X-ray astronomy satellites, along with Chandra and XMM-Newton. Nonetheless, I do not have the sense that the accident has overshadowed Japan's international reputation. Academically and technologically, it is still recognized that Japan is on a par with the United States and Europe in X-ray astronomy.

Though SUZAKU (ASTRO-EII) is smaller than Chandra, which has high resolution, and XMM-Newton, which has a large aperture, it has a unique feature in which it excels over the other two. SUZAKU has high-resolution X-ray spectroscopy, which was derived from the ASCA program, in part through collaboration with the U.S.

Researchers around the world are eagerly awaiting SUZAKU's high-quality X-ray spectroscopic data, because that data is essential in order to analyze results from Chandra and XMM-Newton. In addition, SUZAKU is carrying the most advanced high-energy X-ray detector.
The successful launch of SUZAKU, only five years after the failure of ASTRO-E, reminds me of CORSA-b (HAKUCHO), the replacement for CORSA, in 1979.
I believe that SUZAKU will turn a new page in the world of X-ray astronomy.

In More Depth
? JAXA Interview; Riccardo Giacconi---Nobel-Winning Scientist Has High Hop Scientific Satellites
? ASCA; ISAS/JAXA Department of High Energy Astrophysics
? Astro-E2 Project Home Page

Japan's X-ray Astronomy Research Strategy 1 | 2 | 3
1. What Is X-ray Astronomy? 2. Japan's Leading-Edge X-ray Astronomy 3. ASTRO-EII Launched into Space - Summer 2005
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