Exploring dual and binary AGN through multi-wavelength observations

Hierarchical models of galaxy formation predict that galaxy mergers represent a key transitional stage of rapid Super-Massive Black Holes (SMBHs) growth. However, the lack of a census of AGN pairs over cosmic time prevents us from firmly connecting BH triggering and merging processes. 
Detecting dual AGN -- active SMBHs at projected separations larger than several parsecs -- and binary AGN -- active SMBHs  bound in a Keplerian binary -- remains both  an observational and theoretical challenge. These systems encode crucial information about the formation and accretion history of SMBHs across cosmic ages and are expected to be among the loudest gravitational waves emitters at low-frequencies. 
The talk will review observational efforts across the electromagnetic spectrum aimed at detecting and characterizing dual and binary SMBHs. It will also discuss the broader implications of these findings in the context of current black hole merger simulations and highlight the potential of future multi-messenger studies with upcoming space-based observatories.