Kavli Affiliate: Claudio Ricci
| First 5 Authors: Federico Esposito, Federico Esposito, , ,
| Summary:
The distribution of molecular gas on small scales regulates star formation
and the growth of supermassive black holes in galaxy centers, yet the role of
active galactic nuclei (AGN) feedback in shaping this distribution remains
poorly constrained. We investigate how AGN influence the small-scale structure
of molecular gas in galaxy centers, by measuring the clumpiness of CO(3 – 2)
emission observed with the Atacama Large Millimeter/submillimeter Array (ALMA)
in the nuclear regions (50 – 200 pc from the AGN) of 16 nearby Seyfert galaxies
from the Galaxy Activity, Torus, and Outflow Survey (GATOS). To quantify
clumpiness, we apply three different methods: (1) the median of the
pixel-by-pixel contrast between the original and smoothed maps; (2) the ratio
of the total excess flux to the total flux, after substracting the background
smoothed emission; and (3) the fraction of total flux coming from clumpy
regions, interpreted as the mass fraction in clumps. We find a negative
correlation between molecular gas clumpiness and AGN X-ray luminosity (L_X),
suggesting that higher AGN activity is associated with smoother gas
distributions. All methods reveal a turnover in this relation around L_X =
10^42 erg/s, possibly indicating a threshold above which AGN feedback becomes
efficient at dispersing dense molecular structures and suppressing future star
formation. Our findings provide new observational evidence that AGN feedback
can smooth out dense gas structures in galaxy centers.
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