Resonant axion radiation conversion in solar spicules

Abstract

It has recently been observed that solar spicules covering almost all of solar surface have strong magnetic field [Formula: see text]. They are supposed to be plasma jets emitted from chromosphere and they arrive up to [Formula: see text]. Their electron number density is such that [Formula: see text]. Corresponding plasma frequency [Formula: see text] (electron mass [Formula: see text]) is nearly equal to axion mass [Formula: see text]. Thus, resonant radiation conversion of axion with the mass can arise in the spicules. We show that radiations converted from axion dark matter possess flux density [Formula: see text]. The radiations show line spectrum with frequency [Formula: see text]. Our estimation has fewer ambiguities in physical parameters than similar estimation in neutron stars because physical parameters like electron number density have been more unambiguously observed in the sun. But, much strong solar thermal radiations would preclude sensitive observations of such radiations from the axions.