Herschel Spectroscopy of Early Type Galaxies
  We present Herschel spectroscopy of atomic lines arising in photodissociation
regions as well as ionization regions of nearby early-type galaxies (ETGs),
focusing on the volume-limited Atlas3D sample. Our data include the [CII],
[OI], and [NII] 122 and 205 micron lines, along with ancillary data including
CO and HI maps. We find ETGs have [CII]/FIR ratios slightly lower than spiral
galaxies in the KINGFISH sample, and several ETGs have unusually large [NII]
122/[CII] ratios. The [NII] 122/[CII] ratio is correlated with UV colors and
there is a strong anti-correlation of [CII]/FIR with NUV-K seen in both spirals
and ETGs, likely due to a softer radiation field with fewer photons available
to ionize carbon and heat the gas. The correlation thus makes a [CII] deficit
in galaxies with redder stellar populations. The high [NII] 122/[CII] (and low
[CII]/FIR) line ratios could also be affected by the removal of much of the
diffuse, low density gas, which is consistent with the low HI/H2 ratios. [CII]
is now being used as a star formation indicator, and we find it is just as good
for ETGs as in spirals. The [CII]/CO ratios found are also similar to those
found in spiral galaxies. Through use of the [NII] 205 micron line, estimates
of the percentage of [CII] emission arising from ionized gas indicate a
significant portion could arise in ionized regions.
