Properties of dust and PAHs in the hot plasma of the elliptical galaxy NGC4125 revealed with AKARI and Spitzer

TL;DR

This study maps the distribution of dust and PAHs in galaxy NGC4125, revealing their different spatial patterns and suggesting interactions with hot plasma, providing insights into their origins and behavior in elliptical galaxies.

Contribution

It provides the first detailed spatial comparison of dust and PAHs with hot plasma in NGC4125, highlighting their distinct distributions and potential protective mechanisms.

Findings

PAHs are concentrated in a central dust lane, likely protected from X-ray plasma.

Dust emission is more extended, correlating with X-ray plasma distribution.

PAHs and dust have different spatial distributions, indicating varied interactions with hot plasma.

Abstract

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.