Understand
From a Chandra sample of active galactic nuclei (AGNs) in nearby galaxies, we find that for low-luminosity AGNs (LLAGNs), either the intrinsic absorption column density, or the fraction of absorbed AGNs, positively scales with the Eddington ratio for $L_{\rm bol}/L_{\rm Edd} \lesssim 10^{-2}$.
- Such a behavior, along with the softness of the X-ray spectrum at low luminosities, is in good agreement with the picture that they are powered by hot accretion flows surrounding supermassive black holes.
- Numerical simulations find that outflows are inevitable with hot accretion flows, and the outflow rate is correlated with the innermost accretion rate in the low-luminosity regime.
- This agrees well with our results, suggesting that the X-ray absorption originates from or is associated with the outflow material.
Reading the bibliography…