May 11, 2020
Keio University
National Astronomical Observatory of Japan
A research team, consisting of Yuhei Iwata (a third-year student in the Doctoral Programs at the Graduate School of Science and Technology, Keio University), Professor Tomoharu Oka from the Department of Physics, Faculty of Science and Technology, JAXA, and the National Astronomical Observatory of Japan (NAOJ), has successfully conducted a detailed analysis of observational data of Sagittarius A* (Sgr A*) at the center of the Milky Way galaxy, obtained using the ALMA Telescope, and made precise measurements of the intensity of the radio waves it emits. The results revealed that the radio intensity of Sgr A* varies slowly over periods of more than an hour, while occasionally showing short, periodic variations (flickering) with a period of about 30 minutes. This periodic flickering is interpreted as being caused by a "hot spot" orbiting the supermassive black hole of four million solar masses with a very close orbital radius of 0.2 astronomical units. This research has shown the possibility of depicting phenomena occurring in the immediate vicinity of the supermassive black hole at the galactic center from changes in radio intensity. This is a very important research achievement that will lead to an understanding of the spacetime structure under a strong gravitational field, as described by the general theory of relativity.
The results of this research were published in the April 2 issue of the American astrophysical journal "The Astrophysical Journal Letters."
For the full press release, please see below.