Resurrecting Hitomi for Decaying Dark Matter and Forecasting Leading Sensitivity for XRISM

Area of Science:

• Astrophysics
• Particle Physics
• Cosmology

Background:

• The Hitomi x-ray satellite mission aimed to detect sterile neutrino dark matter (DM) via X-ray line signals.
• Hitomi's mission was cut short, with limited DM decay analyses performed on data from the Perseus cluster.

Purpose of the Study:

• To conduct a more sensitive search for decaying dark matter using archival Hitomi data from blank sky locations.
• To project the future sensitivity of the XRISM satellite for dark matter detection.

Main Methods:

• Analysis of archival Hitomi soft-X-ray spectral data from blank sky regions.
• Projection of XRISM satellite's full-mission sensitivity for similar analyses.

Main Results:

• A significantly more sensitive search for Milky Way dark matter decay was achieved using Hitomi data.
• XRISM is projected to achieve leading sensitivity for decaying dark matter in the 1-18 keV mass range.

Conclusions:

• XRISM satellite will be a crucial instrument for future dark matter searches.
• The findings have significant implications for sterile neutrino and heavy axionlike particle dark matter models.