Universe of Spectroscopy

Author: Yoh Takei

What would you like to introduce to readers in this series?

“Seeing the Universe with X-rays.” This is my research, but for many people it is difficult to visualize. The shining celestial objects in the night sky emit light of wavelengths other than just visible light; they also emit x-rays for example. But, waht are x-rays? What is x-ray spectroscopy? What do you learn from them?

In this series, I would like to familiarize you with the curious topics of x-ray observations and x-ray spectroscopy. On Earth when x-rays are used in hospitals or the security check at an airport, they show the &ldqu;shadow” of an object which the x-rays hit. In contrast, in astronomical observations instead of using an artificial x-ray source, the x-rays are emitted by the celestial objects themselves.

This article introduces a “Galaxy Cluster”, a typical astronomical object where the visible light and x-ray images are totally different. When observed by visible light, there seems to be nothing in the space, but from x-ray observation we know that actually it is filled with high-temperature gas. Our view of galaxy clusters has been changed by x-ray observations. This has implications for the astrophysics of phenomena such as galaxy cluster formation. I am happy when everyone understands this excitement.

My research field and current interests:

I research the structure formation of galaxies and galaxy clusters. focusing on high-temperature gas which radiates x-ray. I should say that right now my galaxy research and galaxy cluster research are separate. In the future, I want to do more unified research. In the near future, the ASTRO-H satellite introduced in this article will allow us to determine the gas velocity which has been unknown until now. I think that the picture of galaxies and galaxy clusters will be changed by the determination of hitherto unmeasured physical quantities.


Yoh Takei
Job Title
Assistant Professor
Field of Expertise
X-ray Astrophysics