Kavli Affiliate: Robert A. Simcoe
| First 5 Authors: Rohan P. Naidu, Jorryt Matthee, Harley Katz, Anna de Graaff, Pascal Oesch
| Summary:
The physical processes that led to the formation of billion solar mass black
holes within the first 700 million years of cosmic time remain a puzzle.
Several theoretical scenarios have been proposed to seed and rapidly grow black
holes, but direct observations of these mechanisms remain elusive. Here we
present a source 660 million years after the Big Bang that displays singular
properties: among the largest Hydrogen Balmer breaks reported at any redshift,
broad multi-peaked H$beta$ emission, and Balmer line absorption in multiple
transitions. We model this source as a "black hole star" (BH*) where the Balmer
break and absorption features are a result of extremely dense, turbulent gas
forming a dust-free "atmosphere" around a supermassive black hole. This source
may provide evidence of an early black hole embedded in dense gas — a
theoretical configuration proposed to rapidly grow black holes via
super-Eddington accretion. Radiation from the BH* appears to dominate almost
all observed light, leaving limited room for contribution from its host galaxy.
We demonstrate that the recently discovered "Little Red Dots" (LRDs) with
perplexing spectral energy distributions can be explained as BH*s embedded in
relatively brighter host galaxies. This source provides evidence that black
hole masses in the LRDs may be over-estimated by orders of magnitude — the BH*
is effectively dust-free contrary to the steep dust corrections applied while
modeling LRDs, and the physics that gives rise to the complex line shapes and
luminosities may deviate from assumptions underlying standard scaling
relations.
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