The Kiloparsec-scale Neutral Atomic Carbon Outflow in the Nearby Type-2
  Seyfert Galaxy NGC 1068: Evidence for Negative AGN Feedback
  Active galactic nucleus (AGN) feedback is postulated as a key mechanism for
regulating star formation within galaxies. Studying the physical properties of
the outflowing gas from AGN is thus crucial for understanding the co-evolution
of galaxies and supermassive black holes. Here we report 55 pc resolution ALMA
neutral atomic carbon [CI] $^3P_1\text{-}^3P_0$ observations toward the central
1 kpc of the nearby type-2 Seyfert galaxy NGC 1068, supplemented by 55 pc
resolution CO($J=1\text{-}0$) observations. We find that [CI] emission within
the central kpc is strongly enhanced by a factor of $>$5 compared to the
typical [CI]/CO intensity ratio of $\sim$0.2 for nearby starburst galaxies (in
units of brightness temperature). The most [CI]-enhanced gas (ratio $>$ 1)
exhibits a kpc-scale elongated structure centered at the AGN that matches the
known biconical ionized gas outflow entraining molecular gas in the disk. A
truncated, decelerating bicone model explains well the kinematics of the
elongated structure, indicating that the [CI] enhancement is predominantly
driven by the interaction between the ISM in the disk and the highly inclined
ionized gas outflow (which is likely driven by the radio jet). Our results
strongly favor the "CO dissociation scenario" rather than the "in-situ C
formation" one which prefers a perfect bicone geometry. We suggest that the
high [CI]/CO intensity ratio gas in NGC 1068 directly traces ISM in the disk
that is currently dissociated and entrained by the jet and the outflow, i.e.,
the "negative" effect of the AGN feedback.
