Overview

The X-ray astronomy satellite “Hitomi” was equipped with detectors that provided a broader wavelength range and over ten times the sensitivity of previous X-ray astronomy satellites. Its mission aimed to capture the large-scale structure of the universe and its evolution, tackling the mysteries of dark matter and the co-evolution of galaxies and black holes. Hitomi was launched on February 17, 2016, from the Tanegashima Space Center by an H-IIA rocket. However, communication was lost due to a malfunction in the satellite’s attitude control system on March 26 of the same year, and the mission was abandoned on April 28.

The satellite’s objectives included exploring the extreme universe filled with high-energy phenomena around black holes and supernova explosions and observing galaxy clusters filled with hot plasma. These observations were expected to provide insights into the structure and evolution of the universe.

Observation Instruments

Soft X-ray Spectrometer (SXS)

The SXS is a microcalorimeter spectrometer that measures X-rays in the energy range of 0.3 to 12 keV. It is designed to obtain X-ray spectra with extremely high precision, particularly for detailed analysis of the physical properties of hot plasma.

Soft X-ray Imager (SXI)

The SXI uses an X-ray CCD camera and can perform imaging and spectroscopic observations of X-ray celestial objects in the energy range of 0.4 to 12 keV. It is designed for wide-field X-ray imaging, making it suitable for observing extended celestial objects such as galaxies, galaxy clusters, and supernova remnants.

Hard X-ray Imager (HXI)

The HXI uses CdTe detectors, offering high sensitivity and spatial resolution. In conjunction with the hard X-ray telescope (HXT), it enables imaging and spectroscopic observations in the high-energy X-ray range of 5 to 80 keV. It is suitable for observing high-energy celestial objects such as black holes and neutron stars.

Soft Gamma-ray Detector (SGD)

The SGD is designed to observe high-energy phenomena such as gamma-ray bursts and supernova explosions. It uses a combination of silicon and CdTe detectors, providing high energy resolution and sensitivity in the wide energy range of 60 to 600 keV.

Achievements

Although Hitomi lost communication shortly after starting its operations and was unable to acquire extensive observational data, it did obtain some new results on the Perseus cluster and the Crab Nebula. The successor to Hitomi, the XRISM satellite launched in 2023, is expected to yield new insights into the large-scale structure and evolution of the universe, the nature of dark matter, and the co-evolution of galaxies and black holes.