Hidden axion dark matter decaying through mixing with QCD axion and the 3.5 keV X-ray line

Abstract

Hidden axions may be coupled to the standard model particles through a kinetic or mass mixing with QCD axion. We study a scenario in which a hidden axion constitutes a part of or the whole of dark matter and decays into photons through the mixing, explaining the 3.5 keV X-ray line signal. Interestingly, the required long lifetime of the hidden axion dark matter can be realized for the QCD axion decay constant at an intermediate scale, if the mixing is sufficiently small. In such a two component dark matter scenario, the primordial density perturbations of the hidden axion can be highly non-Gaussian, leading to a possible dispersion in the X-ray line strength from various galaxy clusters and near-by galaxies. We also discuss how the parallel and orthogonal alignment of two axions affects their couplings to gauge fields.

19 pages

References in corpus (24)

• Light Sterile Neutrinos: A White Paper
• SUSY Breaking in Local String/F-Theory Models
• Natural inflation with multiple sub-Planckian axions
• The Need for Purely Laboratory-Based Axion-Like Particle Searches
• The Poker Face of the Majoron Dark Matter Model: LUX to keV Line
• Resonantly-Produced 7 keV Sterile Neutrino Dark Matter Models and the Properties of Milky Way Satellites
• Update of axion CDM energy density
• Improved estimation of radiated axions from cosmological axionic strings
• Thermal axion production in the primordial quark-gluon plasma
• Moduli/Inflaton Mixing with Supersymmetry Breaking Field
• Axion cold dark matter in view of BICEP2 results
• The 7 keV axion dark matter and the X-ray line signal
• A 3.55 keV Photon Line and its Morphology from a 3.55 keV ALP Line
• Natural and Multi-Natural Inflation in Axion Landscape
• 3.55 keV photon lines from axion to photon conversion in the Milky Way and M31
• Anomaly-free flavor models for Nambu-Goldstone bosons and the 3.5 keV X-ray line signal
• Limits on Isocurvature Perturbations from Non-Gaussianity in WMAP Temperature Anisotropies
• Non-Gaussianity from Symmetry
• General treatment of isocurvature perturbations and non-Gaussianities
• A 3.55 keV line from $\text{DM}\to a\to \gamma$: predictions for cool-core and non-cool-core clusters
• The 3.5 keV X-ray line signal from decaying moduli with low cutoff scale
• Cluster X-ray line at $3.5\mathrm{keV}$ from axion-like dark matter
• Relaxing Isocurvature Bounds on String Axion Dark Matter
• Primordial Trispectrum from Isocurvature Fluctuations

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• QCD Axion on Hilltop by a Phase Shift of $\pi$
• Nonthermal Two Component Dark Matter Model for Fermi-LAT $\gamma$-ray excess and 3.55 keV X-ray Line
• Cosmic Birefringence Triggered by Dark Matter Domination
• Cosmological Tension of Ultralight Axion Dark Matter and its Solutions
• Non-abelian Dark Matter Solutions for Galactic Gamma-ray Excess and Perseus 3.5 keV X-ray Line
• Axion Periodicity and Coupling Quantization in the Presence of Mixing
• Observational consistency and future predictions for a 3.5 keV ALP to photon line
• Early dark energy by dark Higgs, and axion-induced non-thermal trapping
• Induced Domain Walls of QCD Axion, and Gravitational Waves
• Resonant production of dark photons from axion without a large coupling
• Axion-like particle oscillations
• Inflaxion Dark Matter
• Phenomenology of the companion-axion model: photon couplings
• Reheating-Induced Axion Dark Matter After Low Scale Inflation
• Resolving the QCD Axion Domain Wall Problem with a Light Axion
• Cosmic Birefringence as a probe of dark matter nature: Sterile neutrino and dipolar dark matter
• ALP Anarchy
• Cosmology of the companion-axion model: dark matter, gravitational waves, and primordial black holes