Characterizing the early build-up of supermassive black holes (MBH> 106 Msun) requires moving beyond traditional diagnostics. I will discuss two populations of active galactic nuclei (AGN) that were systematically missed before the advent of the James Webb Space Telescope: the « Little Red Dots » (LRDs) and « wandering » AGN. Uncovering these AGN allows us to track some of the key formation channels of SMBHs: accretion onto BH seeds and mergers. Firstly, I will present compelling evidence for AGN-heated dust (with T~800 K) being common in the rest-frame near-infrared (1-3 μm) of LRDs, as revealed through median stacking of their NIRCam, MIRI (and ALMA) images. I will discuss caveats and implications of our findings in the framework of state-of-the-art LRD models. Secondly, I will present a recent NIRSpec/IFU follow-up of a promising wandering AGN candidate at z=0.93. Located in the COSMOS-Web area, this system features an on-going galaxy merger where one AGN (identified via radio VLBI) appears to be roaming 3 kpc away with no underlying stellar continuum, potentially representing the first confirmed wandering AGN fully decoupled by tidal interactions. I will conclude by outlining strategies to map the demographics of these hidden populations using current/future wide-area facilities, like Euclid, Roman, and the ngVLA/SKA.
Contact local & organisation: Emanuele DADDI
DAp