Oral Abstract

Invited talk (I0.4) Hiroki Akamatsu (SRON)

Development of a cryogenic microcalorimeter towards high-resolution X-ray spectroscopy

A large majority of baryonic matter in the present universe states in hot plasma form (T~10^5-10^8 K).
Such hot plasma strongly emits X-rays commonly. Most of the emission lines from the atomic K-, L-, M-shells occur in the X-ray band.
These lines enable us to investigate 1.) the dynamics of the plasma, 2.)chemical compositions and 3.) non-equilibrium/non-thermal phenomena.
These unique capabilities of the X-ray spectroscopy offer a new observational window to understand the nature of the hot Universe.
However, due to the lack of the spectroscopic capability in conventional spectrometers, the full diagnostic power to understand the Universe could not be exploited yet.

The state-of-art cryogenic X-ray spectrometers will innovate this situation because of their spectral resolving power, which is 2 orders better than conventional spectrometers. Hitomi satellite was the first to demonstrate the power of high-resolution X-ray spectroscopy on the cosmic plasmas in the Perseus cluster. However, due to the loss of control of the Hitomi satellite only one cluster has been observed. Upcoming XRISM and Athena projects will enable us to fully conduct high-resolution X-ray spectroscopy.

In this talk, we will briefly introduce the basics of X-ray spectroscopy and challenges for cryogenic X-ray spectrometers.