Star formation in the local Universe from the CALIFA sample. II.
  Activation and quenching mechanisms in bulges, bars, and disks
  We estimate the current extinction-corrected H$\alpha$ star formation rate
(SFR) of the different morphological components that shape galaxies (bulges,
bars, and disks). We use a multi-component photometric decomposition based on
SDSS imaging to CALIFA Integral Field Spectroscopy datacubes for a sample of
219 galaxies. This analysis reveals an enhancement of the central SFR and
specific SFR (sSFR $=$ SFR/$M_{\star}$) in barred galaxies. Along the Main
Sequence, we find more massive galaxies in total have undergone efficient
suppression (quenching) of their star formation, in agreement with many
studies. We discover that more massive disks have had their star formation
quenched as well. We evaluate which mechanisms might be responsible for this
quenching process. The presence of type-2 AGNs plays a role at damping the sSFR
in bulges and less efficiently in disks. Also, the decrease in the sSFR of the
disk component becomes more noticeable for stellar masses around 10$^{10.5}$
M$_{\odot}$; for bulges, it is already present at $\sim$10$^{9.5}$ M$_{\odot}$.
The analysis of the line-of-sight stellar velocity dispersions ($\sigma$) for
the bulge component and of the corresponding Faber-Jackson relation shows that
AGNs tend to have slightly higher $\sigma$ values than star-forming galaxies
for the same mass. Finally, the impact of environment is evaluated by means of
the projected galaxy density, $\Sigma$$_{5}$. We find that the SFR of both
bulges and disks decreases in intermediate-to-high density environments. This
work reflects the potential of combining IFS data with 2D multi-component
decompositions to shed light on the processes that regulate the SFR.
