Bosonic super-WIMPs as keV-scale dark matter

TL;DR

This paper investigates keV-scale bosonic super-WIMPs as dark matter candidates, analyzing their cosmological, astrophysical, and detection constraints, and identifying models with potentially detectable signals in direct detection experiments.

Contribution

It provides a comprehensive analysis of bosonic super-WIMPs in the keV mass range, highlighting models with enhanced direct detection prospects and evaluating their cosmological and astrophysical impacts.

Findings

Certain models allow photoelectric absorption detection surpassing existing constraints.

Annual modulation signals are predicted but are too small to observe with current technology.

Models are consistent with cosmological and stellar constraints while offering new detection avenues.

Abstract

We consider models of light super-weakly interacting cold dark matter, with O(10-100) keV mass, focusing on bosonic candidates such as pseudoscalars and vectors. We analyze the cosmological abundance, the gamma-background created by particle decays, the impact on stellar processes due to cooling, and the direct detection capabilities in order to identify classes of models that pass all the constraints. In certain models, variants of photoelectric (or axioelectric) absorption of dark matter in direct-detection experiments can provide a sensitivity to the superweak couplings to the Standard Model which is superior to all existing indirect constraints. In all models studied, the annual modulation of the direct-detection signal is at the currently unobservable level of O(10^{-5}).