SMBHs as Cosmic Architects: Dual-Channel Origins and Transition Epochs(𝑧∼3–6) When Causality Reverses

Supermassive blackholes (SMBHs) with are now observed at cosmic dawn (𝑧>6) in chemically primitive, low-stellar mass systems (e.g. Mortlock etal. 2011; Wang etal. 2021; Labbé etal. 2023; Harikane etal. 2022; Treu etal. 2023), implying that in at least some early environments black hole growth precedes the assembly of the bulk of the host galaxy. At late times, however, SMBHs are almost exclusively found in dynamically relaxed bulges whose properties correlate tightly with blackhole mass (e.g. Ferrarese & Merritt 2000; Gebhardt etal. 2000; Marconi & Hunt 2003; Graham & Driver 2007; Kormendy & Ho 2013), indicating a galaxy-first, blackhole-second sequence. This work addresses the resulting causal tension: when in cosmic history does the dominant direction of this relationship reverse, and what physics enforces that change?