Properties of dust and PAHs in the hot plasma of the elliptical galaxy
  NGC4125 revealed with AKARI and Spitzer
  We present the spatial distributions of dust and polycyclic aromatic
hydrocarbons (PAHs) in the elliptical galaxy NGC4125, revealed by AKARI and
Spitzer. NGC4125 is relatively bright in the dust and the PAH emision for
elliptical galaxies, although it certainly possesses diffuse interstellar hot
plasma indicated by the high spatial resolution X-ray data of Chandra. We
investigate how the dust and PAHs interact with the X-ray plasma or avoid the
interaction by comparing their spatial distributions. We find that the
distributions of the PAHs and dust are different from each other, both showing
a significant deviation from a smooth stellar distribution. The PAH emission
predominantly comes from a dust lane, a compact dense molecular gas region in
the galactic center, where the PAHs are likely to have been protected from the
interaction with the X-ray plasma. The dust emission has more extended
structures similar to the distribution of the X-ray plasma, suggesting their
interaction to some extent. We also discuss a possible origin of the dust and
PAHs in the galaxy.
