Not Dead Yet: Cool Circumgalactic Gas in the Halos of Early Type
  Galaxies
  We report new observations of circumgalactic gas in the halos of early type
galaxies obtained by the COS-Halos Survey with the Cosmic Origins Spectrograph
onboard the Hubble Space Telescope. We find that detections of HI surrounding
early type galaxies are typically as common and strong as around star-forming
galaxies, implying that the total mass of circumgalactic material is comparable
in the two populations. For early type galaxies, the covering fraction for HI
absorption above 10^16 cm^2 is ~40-50% within ~150 kpc. Line widths and
kinematics of the detected material show it to be cold (T ~< 10^5 K) in
comparison to the virial temperature of the host halos. The implied masses of
cool, photoionized CGM baryons may be up to 10^9 --- 10^11 Msun. Contrary to
some theoretical expectations, strong halo HI absorbers do not disappear as
part of the quenching of star-formation. Even passive galaxies retain
significant reservoirs of halo baryons which could replenish the interstellar
gas reservoir and eventually form stars. This halo gas may feed the diffuse and
molecular gas that is frequently observed inside ETGs.
