  We have studied the signals from axion-like particles (ALPs) as dark matter
mediators from celestial objects such as neutron stars or brown dwarfs. We
consider the accumulation of dark matter inside the celestial objects using the
multiscatter capturing process. The production of ALP from the dark matter
annihilation can escape the celestial object and decay into gamma-ray and
neutrinos before reaching the Earth. We investigate our model using gamma-ray
observations from Fermi and H.E.S.S and neutrino observations from IceCube and
ANTARES. The effective Lagrangian approach allows us to place constraints on
the ALP-photon and ALP-fermion couplings. In the gamma-ray channel, our results
improve the existing bounds on ALPs by 1-2 orders of magnitude. Although the
constraints from neutrino fluxes rule out a significant portion of the
parameter space, the remaining part of the parameter space is accessible by
future experiments.
