We will discuss two promising dark matter scenarios: axion-like particle dark matter and primordial black hole dark matter. We begin with radio telescope probes on axion-like dark matter. We will discuss the axion-photon conversion around neutron stars which results in the radio emission and the 21 cm probes through the effects on large scale structure formation suppression. We then turn our attention to primordial black hole dark matter. We will explore multi-messenger approaches to investigate the dark matter environments surrounding black holes. The constraints to be discussed include radio signals, CMB, gamma rays, and gravitational waves. The complementarity of these observational signals will also be highlighted.
