Speaker
Description
One of the most remarkable discoveries by the James Webb Space Telescope is a population of red, compact, high-redshift galaxies known as Little Red Dots (LRDs). The presence of broad Balmer emission lines suggests active galactic nuclei powered by supermassive black holes (BHs), while LRDs exhibit unusually weak X-ray and radio emission and low variability, posing a significant puzzle. We propose that the BH is embedded in a massive, optically thick envelope. The BH envelope radiates as a blackbody at the Hayashi limit, naturally explaining the red colors of LRDs. In addition, the dynamical timescale at the photosphere is consistent with the observed year-scale variability. The BH envelope may also serve as a hidden source of high-energy neutrinos.