JAXA Japan Aerospace Exploration Agency

Q. What kind of research would you like to carry out with the X-ray Astronomy Satellite ASTRO-H?

An image of the Perseus galaxy cluster observed with the Chandra X-ray Observatory. The super-massive black hole in the middle of the galaxy cluster influences the surrounding area. (courtesy: NASA/CXC/loA/A.Fabian et al.)

Suzaku observed X-rays extending in two directions from the center of the Perseus galaxy cluster. Red indicates X-rays and brighter gas, and blue indicates X-rays and dark gas. The circular undulating line shows the rim of the galaxy cluster, which has a diameter of 11.6 million light years. Gas several million degrees Celsius in temperature lies at the outer rim of the galaxy. (courtesy: NASA/ISAS/DSS/A.Simionescu et al.)

There have been several examples of observed proof that massive black holes at the center of a galaxy cluster provide heat to the surrounding gas. For example, this is a photo of the center of the Perseus cluster, observed with the United States’ Chandra X-ray Observatory. There is a black hole in the middle of the galaxy cluster, and it looks like it’s somehow affecting the surrounding area. It is assumed that some kind of waves heat the surrounding gas, but we don’t understand how this happens. Perhaps a high-energy jet gushing out of a black hole stirs and heats the surrounding gas. ASTRO-H can precisely measure the speed of this gas that surrounds a black hole, so I’d like to research the movement of this gas in detail. I’d love to find out whether energy jets from black holes really do provide energy to the surrounding gas.
In addition, using ASTRO-H’s wideband X-ray imaging capabilities, we can determine how black holes release energy. If we can understand the mechanism of X-ray emission, we may be able to devise a formula to calculate the mass of black holes in other galaxies. I’m eager to do such research as well.
Furthermore, I’d like to reveal the evolution of the structure of the universe. I will try to untangle the mysteries of space history, such as how and when these massive black holes were created, as well as how this affected the formation of galaxies, etc.

Q. What is the most impressive achievement of Japanese X-ray astronomy satellites to date?

Artist’s rendition of a black hole obscured by gas and dust.

The discovery of an active, super-massive black hole that was covered by dense gas and dust, through observations by the Japanese X-ray Astronomy Satellite Suzaku and the U.S. astronomy satellite Swift. This black hole was buried in the middle of a celestial object that at first glance looked like a normal galaxy. When observed by optical light, it looks like any other galaxy, but X-rays revealed that there is a black hole inside it.
Other black holes are surrounded by a donut-shaped cloud of gas and dust, but this one is covered all over by gas and dust, which form a kind of shell. Such a black hole is thought to be in the middle of its growth period, when a black hole and galaxy grow together. It had previously been thought that many newborn galaxies and black holes might exist, but that was the first time one was actually found.
Using high-energy X-rays, ASTRO-H can observe these black holes that are hidden from normal view by surrounding gas and dust. If it can find many of them, this could be a clue to understanding the origin and evolution of massive black holes. It could tell us how many existed in the past, how many objects are falling into black holes, and how much growth black holes experienced.

Q. What is the charm of astronomy for you?

Originally, I read a book about astronomy and it seemed interesting. I thought, “I’d like to know about the universe and galaxies.” That was the motivation for me to go down this path. Now, I’m actually making observations of objects I wanted to study and analyzing their data. There is a possibility for me to discover something new. We could be the first ones to see a new astronomical phenomenon. That’s the charm of astronomy.