JAXA Japan Aerospace Exploration Agency

Q. Are there any joint observations with other astronomical satellites or ground observatories?

MAXI’s flash report system

Yes, we collaborate quite often with other astronomical satellites and ground observatories. It is very important to make simultaneous observations not only with X-ray wavelengths, but also with different wavelengths such as gamma- rays, radio waves and visible light. Thus we have developed a system to get that kind of cooperation: as soon as we discover something, such as a new astronomical object or a transient phenomenon such as a jet ejection or burst, we send a flash report to the world’s astronomical community. This way, we make simultaneous observations with multi-wavelengths. Currently, we try to send out the flash report between two and 24 hours after the discovery, but we are trying to improve the system so that the reports can be sent automatically within 30 seconds of a discovery for the best case.
To date, we have performed collaborative research with the U.S. Swift Gamma-Ray Burst Explorer, the Japanese X-ray Astronomy Satellite Suzaku, the Italian high-energy astrophysics satellite AGILE, a radio astronomy group in the United Kingdom, and the optical telescope in Hawaii as well as various satellites, ground observatories and research groups in Japan and abroad. Q. What’s kind of reputation has MAXI internationally? When we report our results at international astronomy conferences, we receive high praise from many persons. The number of flash reports to astronomers in the world, which I mentioned previously, totals more than 35 so far, and these are helping promote multiple-wavelength observations. We are getting more inquiries about collaborative research.
We also publish the observation data from MAXI on the web site of the RIKEN institute. Currently we are updating data on more than 200 X-ray-emitting objects every day. This web site is accessed about 500 times a day, and half of these visitors are from abroad. That demonstrates the high level of interest in MAXI’s data among international scientists. We welcome collaboration with researchers from all over the world, and would like to continue to expand our international activities.

Related Link: Web site for MAXI’s public data

Q. What kind of influence do you think the observation results from MAXI will have on future space research?

Two black holes at the center of galaxy NGC6240, about to crash into each other. A composite image using observation data from the Hubble Space Telescope and the Chandra X-ray Observatory. (Courtesy: X-ray (NASA/CXC/MIT/C. Canizares, M. Nowak); Optical (NASA/STScI))


Artist’s rendition of a gamma-ray burst (Courtesy: ESO/A. Roquette)

MAXI is more sensitive than previous all-sky X-ray observation payloads, so I think we have a better chance of obtaining interesting phenomena early and performing simultaneous observations at multi-wavelengths. In addition, since MAXI observes the sky continuously with a wider field of view, it can monitor about 500 or more astronomical objects at once. Long-duration observations with this improvement give us chances of encountering new aspects of variability of astronomical objects, and allow us to carry out our research systematically.
For example, long-term observation is a very effective way to study active galactic nuclei. Active galaxies are special galaxies with a huge massive black hole at the center, and they are still not well understood. Observing them over a long period, we may have a chance to detect periodic or quasi-periodic variability for the first time. In addition, we have already observed the coalescence of massive black holes, but if we could capture the signs of such an event prior to coalescence, that would be a great discovery. When celestial objects coalesce, X-rays are released, so if we keep observing the X-rays over time before the coalescence occurs, we might be able to detect a "gravitational wave" for the first time. I think it is very important to detect these moments of such variability. Q. What kind of research do you want to perform with MAXI in the future? I’d like to systematize the causes of intensive variabilities of celestial objects. Specifically, I’d like to conduct systematic observation of various jets generated in the Universe. For instance, we are observing an X-ray source in the constellation Circinus - an X-ray binary star system known as Circinus X-1 - in collaboration with radio-wave astronomy researchers. During our continuous observations with MAXI, we detected several small bursts - or flares - of X-rays. Our Dutch radio-wave collaborators pointed their instruments in the same direction, and detected a small jet of matter. In the past, without this kind of collaborative observation, these small jets were hard to detect. So this stimulated our confidence in our ability to detect smaller celestial phenomena such as these.
There is some variety of the jet scale. There are jets from enormous active galaxies, neutron stars, black holes, and solar flares. But these jets are sudden phenomena and we cannot predict where and when they will occur, so it is very hard to find them unless we are observing the entire sky. For this reason, these jets have rarely been observed with X-rays till now. Since MAXI detected the moment of jet generation through X-rays generated from Circinus X-1, worldwide expectations for MAXI have gone up.
As I explained, I’d like to collect a good deal of observation data on various sized jets, and my goal is to systematize this information.

Q. What do you think is the appeal of astronomy?

Space and life are eternal research themes for humanity. Space is a very deep and broad topic, and you don’t know what will emerge next. That’s why it appeals to me. There are a lot of things in space that we don’t understand, and these mysteries are not easy to solve. For example, gamma-ray bursts were first detected more than 40 years ago, and that discovery spread through the world of astronomy, leading to breakthrough discoveries of supernovas, space jets and the early phase of cosmic evolution, but many things still remain unknown. That’s the attractive part of astronomy that drives our curiosity.