Observational confirmation of hot accretion model predictions has been hindered by the challenge to resolve spatially the Bondi radii of black holes with X-ray telescopes .
Here , we use the Megasecond Chandra X-ray Visionary Project ( XVP ) observation of the NGC 3115 supermassive black hole to place the first direct observational constraints on the spatially and spectroscopically resolved structures of the X-ray emitting gas inside the Bondi radius of a black hole .
We measured temperature and density profiles of the hot gas from a fraction out to tens of the Bondi radius ( R _ { B } = 2 \farcs 4–4 \farcs 8 = 112–224 pc ) .
The projected temperature jumps significantly from \sim 0.3 keV beyond 5″ to \sim 0.7 keV within \sim 4 \arcsec –5″ , but then abruptly drops back to \sim 0.3 keV within \sim 3 ″ .
This is contrary to the expectation that the temperature should rise toward the center for a radiatively inefficient accretion flow .
A hotter thermal component of \sim 1 keV inside 3″ ( \sim 150 pc ) is revealed using a two component thermal model , with the cooler \sim 0.3 keV thermal component dominating the spectra .
We argue that the softer emission comes from diffuse gas physically located within \sim 150 pc from the black hole .
The density profile is broadly consistent with \rho \propto r ^ { -1 } within the Bondi radius for either the single temperature or the two-temperature model .
The X-ray data alone with physical reasoning argue against the absence of a black hole , supporting that we are witnessing the onset of the gravitational influence of the supermassive black hole .