TOP > Report & Column > The Forefront of Space Science > 2015 > The X-ray universe that MAXI was watching for five years

| 1 | 2 | 3 | Monitor of All-sky X-ray Image (MAXI) Monitor of All-sky X-ray Image (MAXI) has been installed on outside of the Japanese Experiment Module "Kibo" of the International Space Station (ISS) and in the vacuum of space. MAXI, the Japanese device proposed by RIKEN, was attached by astronaut Koichi Wakata in 2009. Since then, it has watched the X-ray universe every 92 minutes. X-ray universe fluctuates intensely. X-ray nova (such as neutron star or black hole binary stars) suddenly appears and X-ray star irregularly brightens and dims, which is described in detail in February 2011 Issue. MAXI records the intensity variation, the result of the gas slit camera (GSC) is open to public on the website of MAXI (http://maxi.riken.jp/) every four hours. MAXI has been working as the only all-sky monitor in the X-ray band all over the world since X-ray all-sky monitor (ASM) of RXTE satellite, which had worked as the all-sky X-ray monitor, stopped operation in the end of 2011. When it’s in real-time connection, the data arrives at RIKEN in about 10 seconds over Tracking and Data Relay Satellite (TDRSS)-NASA- The Tsukuba Space Center. At the MAXI room of Tsukuba, nova finding program "Nova search" monitors the appearance of nova at all times and reports about it automatically if it is a sure event. The appearance of nova with a low accuracy is once emailed to a mobile phone of the scientist on duty, after checking, he posts it on international Astronomical Telegrams (ATel) or The Gamma-ray Coordinates Network (GCN) when it is a real. About 177 to ATel and 65 to GCN have been reported promptly for five years. During this period, MAXI found15 new celestial bodies including six black hole binary stars. Received the news that MAXI discovered novas, astronomers around the world have observed them with telescopes such as for visible light or for X-ray and have clarified their identity. X-ray all-sky image and X-ray catalog of 21 century Figure1 is the X-ray all-sky image that MAXI has obtained for 4.1 years. Low-energy images of Solid-state Slit Camera(SSC) are represented in red, and Cygnus Loop (Veil Nebula) and Vela supernova remnant (Vela SNR) are noticeable as spread red circles. North Polar Spur also extends from the center to the upper side with pale red. In the March issue of 2013, we announced that it can be considered that Cygnus Superbubble, large structure which is 11-degrees radius of Cygnus, is a trace of an explosion which a single hypernova has caused about 300 million years ago. We detected 500 X-ray celestial bodies, which is more significance than 7σ(its intensity is more than about 0.6mCrab) from the sky of high galactic latitude (|b|> 10 degrees) and announced them as the second edition of the MAXI catalog. This is the no-bias all-sky catalog in 2~10keV band since the 1980s�EHEAO-I satellite and the highest sensitivity ever. Although the total number of the detected active galactic nucleus (AGN) was almost the same, about half of individual AGN had swapped because of the intensity change. So to speak, it became "21st century’s catalog of X-ray celestial body". Figure 1. The X-ray all-sky image taken by MAXI (galactic coordinates) [Click for larger image] The data of 4.1year was used for this image. The brightness represents the intensity of X-rays, and the color represents the energy of X-rays. Red is an X-ray of low energy (0.7~4keV), green is an X-ray of intermediate (4~8keV), and blue is an X-ray of high-energy (8~16keV). We can understand that X-ray stars contain not only yellow and blue stars but also red stars which are greatly expands. Numbers J represent black holes MAXI has found. The numbers represent the right ascension and declination. "MAXI" precedes them as the astronomical name. | 1 | 2 | 3 |

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