Constraints on Ultra Light Dark Matter from Compact Binary Systems

Abstract

The decay of orbital period of a compact binary system (neutron star-neutron star, neutron star-white dwarf) is primarily due to gravitational wave radiation which agrees with the observation. However, there is about one percent mismatch with the GR prediction. In this paper we consider the radiation of axion like particles (ALPs) which can contribute about one percent of the observed decay of the orbital period. If a compact star is immersed in such a low mass axionic potential, it develops a long range field outside the star. For ALPs radiation to take place, the mass of those particles should be less than the orbital frequency of the periodic motion of the binary system. This implies, for most of the observed binaries, particles with mass \(m_a< 10^{-19}eV\) can be radiated which includes fuzzy dark matter (FDM) particles. In this paper, we consider four compact binary systems and we obtain bound on axion decay constant, \(f_a\lesssim \mathcal {O}(10^{11}GeV)\) from the observation of orbital period decay. This implies that if ALPs has to be FDM then they do not couple with gluons.