Heavy concerns about the light axino explanation of the 3.5 keV X-ray line

Abstract

An unidentified 3.5 keV line from X-ray observations of galaxy clusters has been reported recently. Although still under scrutiny, decaying dark matter could be responsible for this signal. We investigate whether an axino with a mass of 7 keV could explain the line, keeping the discussion as model independent as possible. We point out several obstacles, which were overlooked in the literature, and which make the axino an unlikely candidate. The only viable scenario predicts a light metastable neutralino, with a mass between 0.1 and 10 GeV and a lifetime between $10^{-3}$ and $10^4$ s.

5 pages; v2 matches the one published in PLB

References in corpus (6)

• Big-Bang Nucleosynthesis
• Discovery of a 3.5 keV line in the Galactic Center and a Critical Look at the Origin of the Line Across Astronomical Targets
• Axinos as Dark Matter Particles
• X-ray line signal from decaying axino warm dark matter
• Rare meson decays into very light neutralinos
• Measuring a Light Neutralino Mass at the ILC: Testing the MSSM Neutralino Cold Dark Matter Model

Cited by in corpus (5)

• R-parity Violation and Light Neutralinos at CODEX-b, FASER, and MATHUSLA
• R-Parity Violation and Light Neutralinos at SHiP and the LHC
• MeV-GeV $\gamma$-ray telescopes probing axino LSP/gravitino NLSP as dark matter in the $\mu \nu$SSM
• The Supersymmetric R-Parity Violating Dine-Fischler-Srednicki-Zhitnitsky Axion Model
• WIMP Dark Matter in the U$\mu \nu$SSM