Dynamic S0 Galaxies: a Case Study of NGC 5866
  S0 galaxies are often thought to be passively evolved from spirals after star
formation is quenched. To explore what is occurring in S0s, we present a
multi-wavelength study of NGC5866--an isolated nearby edge-on S0. This study
shows strong evidence for dynamic activities in the interstellar medium, which
are most likely driven by supernova explosions in the galactic disk and bulge.
We utilize Chandra, HST, and Spitzer data as well as ground-based observations
to characterize the content, structure, and physical state of the medium and
its interplay with stars in NGC5866. A cold gas disk is detected with an
exponential scale height of 100pc. Numerous off-disk dusty spurs are clearly
present: prominent ones can extend as far as 300pc from the galactic plane and
are probably produced by individual SNe, whereas faint filaments can have ~ kpc
scale and are likely produced by SNe collectively in disk/bulge. We also detect
substantial amounts of diffuse Ha- and Pa-emitting gas with a comparable scale
height as the cold gas. We find that the heating of the dust and warm ionized
gas cannot be explained by the radiation from evolved stars alone, strongly
indicating the presence of young stars in the disk at a low formation rate of ~
0.05Msun/yr. We reveal the presence of diffuse X-ray-emitting hot gas, which
extends as far as 3.5kpc from the disk and can be heated easily by Type Ia SNe
in the bulge. However, the temperature of this gas is ~ 0.2keV, substantially
lower than what might be expected from the mass-loss of evolved stars and Type
Ia SNe heating alone, indicating mass loading from cool gas is important. The
total masses of the cold, warm and hot gases are ~ 5*10^8, 10^4 and 3*10^7Msun.
The relative richness of the gases, undergoing circulations between disk/halo,
is perhaps a result of its relative isolation.
