Axion Quark Nuggets and how a Global Network can discover them

Abstract

We advocate an idea that the presence of the daily and annual modulations of the axion flux on the Earth surface may dramatically change the strategy of the axion searches. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model which was originally put forward to explain the similarity of the dark and visible cosmological matter densities $\Omega_{\rm dark}\sim \Omega_{\rm visible}$. In our framework, the population of galactic axions with mass $ 10^{-6} {\rm eV}\lesssim m_a\lesssim 10^{-3}{\rm eV}$ and velocity $< v_a>\sim 10^{-3} c$ will be always accompanied by the axions with typical velocities $<v_a>\sim 0.6 c$ emitted by AQNs. We formulate the broadband detection strategy to search for such relativistic axions by studying the daily and annual modulations. We describe several tests which could effectively discriminate a true signal from noise. These AQN-originated axions can be observed as correlated events which could be recorded by synchronized stations in the global network. The correlations can be effectively studied if the detectors are positioned at distances shorter than a few hundred kilometres.