Frontier Research Institute for Interdisciplinary Sciences
Tohoku University


Kohei Ichikawa

Assistant ProfessorAdvanced Basic Science

Mentor Information
Masayuki Akiyama (Graduate school of science)
Research Fields Astronomy, Astrophysics
Research Subjects
  • Active galactic nuclei
  • Supermassive black holes
Academic Society Membership Astronomical Society of Japan
Research Outline  

In our universe, there are tremendous numbers of galaxies. Thanks to the great effort on the observations in the previous 30 years, now astronomers believe there is at least one supermassive black hole (SMBH) with the mass between 10^6 to 10^10 times that of the Sun, and it is always located in the center of each galaxy, even in the center of our (Milky Way) galaxy! But still, nobody knows the exact picture of how such SMBHs were formed and acquired such a large amount of mass.

Active galactic nuclei (AGN) are the primary target in these studies as they are accreting surrounding gas and exchanging gravitational potential energy to produce copious amounts of heat and thermal radiation. Although AGN are very bright in all wavelengths, in my research, I am focusing the two key wavelength bands in understanding the growth of SMBHs. One is X-ray, since it emits from the nucleus, meaning that X-ray traces the current AGN power. Another important band is infrared (IR) since IR emission is originated from surrounding dust heated by the central engine. Observations in IR give us how much of dust, or future “fuel” of AGN, are located around the central engine.

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