The impact of quenching on galaxy profiles in the Simba simulation
  We study specific star formation rate (sSFR) and gas profiles of star forming
and green valley galaxies in the Simba cosmological hydrodynamic simulation.
Star-forming galaxy half-light radii ($R_{\rm half}$) at $z=0$ and their
evolution ($\propto(1+z)^{-0.78}$) agree with observations. Passive galaxy
$R_{\rm half}$ agree with observations at high redshift, but by $z=0$ are too
large, owing to numerical heating. We compare Simba $z=0$ sSFR radial profiles
for star forming and green valley galaxies to observations. Simba shows strong
central depressions in star formation rate (SFR), sSFR, and gas fraction in
green valley galaxies and massive star-forming systems, qualitatively as
observed, owing to black hole X-ray feedback, which pushes central gas
outwards. Turning off X-ray feedback leads to centrally peaked sSFR profiles as
in other simulations. In conflict with observations, Simba yields green valley
galaxies with strongly dropping sSFR profiles beyond $\gtrsim R_{\rm half}$,
regardless of AGN feedback. The central depression owes to lowering molecular
gas content; the drop in the outskirts owes to reduced star formation
efficiency. Simba's satellites have higher central sSFR and lower outskirts
sSFR than centrals, in qualitative agreement with observations. At $z=2$ Simba
does not show central depressions in massive star-forming galaxies, suggesting
Simba's X-ray feedback should be more active at high-$z$. High resolution tests
indicate central sSFR suppression is not sensitive to numerical resolution.
Reproducing the central sSFR depression in $z=0$ green valley galaxies
represents a unique success of Simba. The remaining discrepancies highlight the
importance of SFR and gas profiles in constraining quenching mechanisms.
