The cosmic optical background excess, dark matter, and line-intensity mapping

Abstract

Recent studies using New Horizons LORRI images have returned the most precise measurement of the cosmic optical background to date, yielding a flux that exceeds that expected from deep galaxy counts by roughly a factor of two. We investigate whether this excess, detected at $\sim 4\sigma$ significance, is due to axion-like dark matter that decays to monoenergetic photons. We compute the spectral energy distribution from such decays and the contribution to the flux measured by LORRI. Assuming that axion-like particles make up all of the dark matter, the parameter space unconstrained to date that explains the measured excess spans masses and effective axion-photon couplings of 8 - 20 eV masses and 3 - 6 $\times 10^{-11}$ GeV${}^{-1}$, respectively. If the excess arises from dark-matter decay to a photon line, there will be a significant signal in forthcoming line-intensity mapping measurements that will allow the discrimination of this hypothesis from other candidates.

8 pages, 2 figures. Minor modifications, matches published version in PRL

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Cited by in corpus (13)

• Line-Intensity Mapping: Theory Review
• Probing the Blue Axion with Cosmic Optical Background Anisotropies
• Anisotropic cosmic optical background bound for decaying dark matter in light of the LORRI anomaly
• A Measurement of the Cosmic Optical Background and Diffuse Galactic Light Scaling from the R < 50 AU New Horizons-LORRI Data
• Seeking dark matter with $\gamma$-ray attenuation
• Direct-collapse supermassive black holes from relic particle decay
• Thermal production of cold "hot dark matter" around eV
• Novel bounds on decaying axionlike particle dark matter from the cosmic background
• A Spectroscopic Search for Optical Emission Lines from Dark Matter Decay
• Towards Accurate Modeling of Line-Intensity Mapping One-Point Statistics: Including Extended Profiles
• The Glow of Axion Quark Nugget Dark Matter: (I) Large Scale Structures
• Upcoming searches for decaying dark matter with ULTRASAT ultraviolet maps
• Towards a multi-tracer neutrino mass measurement with line-intensity mapping