AXIS Concept Projects 10^31 s Reach for KeV Dark Matter Decay Lines
The AXIS concept study demonstrates how improved X-ray imaging could probe keV dark matter decays at lifetimes of 10^31 s. Projections rely on modeled backgrounds and Galactic center observations, extending existing limits by up to 10x in parts of parameter space. The work serves as a design benchmark for future missions rather than a current detection claim.
The arXiv preprint by Shapir et al. models an AXIS-like instrument with low-background arcsecond imaging, large effective area, and wide field of view across 0.3-10 keV. They calculate projected sensitivities for narrow photon lines from sterile neutrino or axion-like particle decays, focusing on the Galactic center as the target. The calculation incorporates realistic background rates and exposure times to derive the lifetime reach.
Current X-ray bounds on keV-scale dark matter come primarily from diffuse emission searches with Chandra and XMM-Newton, limited by instrumental background and angular resolution. AXIS improves both factors simultaneously, enabling tighter constraints over part of the mass range. This connects to broader efforts in astroparticle physics where X-ray line searches complement direct detection and collider experiments.
A key limitation is that AXIS was not selected for flight, so the projections remain a benchmark rather than an imminent observation. Confirmation would require a funded successor mission with comparable specifications. Stronger evidence would come from end-to-end simulations using actual flight-like data and cross-checks against multiple dark matter density profiles.
Next-gen X-ray mission: 10^31 s DM sensitivity threshold reached in published limits by 2032 if selected for Phase A study.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2608.28738)
- [2]Supporting Source(https://arxiv.org/abs/1602.00021)