Probing multiphase gas in local massive elliptical galaxies via
  multiwavelength observations
  We investigate the cold and warm gas content, kinematics, and spatial
distribution of six local massive elliptical galaxies to probe the origin of
the multiphase gas in their atmospheres. We report new observations, including
SOFIA [CII], ALMA CO, MUSE H$\alpha$+[NII] and VLA radio observations. These
are complemented by a large suite of multiwavelength archival datasets,
including thermodynamical properties of the hot gas and radio jets, which are
leveraged to investigate the role of AGN feeding/feedback in regulating the
multiphase gas content. Our galaxy sample shows a significant diversity in cool
gas content, spanning filamentary and rotating structures. In our non-central
galaxies, the distribution of such gas is often concentrated, at variance with
the more extended features observed in central galaxies. Misalignment between
the multiphase gas and stars suggest that stellar mass loss is not the primary
driver. A fraction of the cool gas might be acquired via galaxy interactions,
but we do not find quantitative evidence of mergers in most of our systems.
Instead, key evidence supports the origin via condensation out of the diffuse
halo. Comparing with Chaotic Cold Accretion (CCA) simulations, we find that our
cool gas-free galaxies are likely in the overheated phase of the self-regulated
AGN cycle, while for our galaxies with cool gas the k-plot and AGN power
correlation corroborate the phase of CCA feeding in which the condensation rain
is triggering more vigorous AGN heating. The related C-ratio further shows that
central/non-central galaxies are expected to generate an extended/inner rain,
consistent with our sample.
