ALMA Observations of Circumnuclear Disks in Early Type Galaxies:
  12CO(2-1) and Continuum Properties
  We present results from an Atacama Large Millimeter/submillimeter Array
(ALMA) Cycle 2 program to map CO(2-1) emission in nearby early-type galaxies
(ETGs) that host circumnuclear gas disks. We obtained $\sim0.3''-$resolution
Band 6 observations of seven ETGs selected on the basis of dust disks in Hubble
Space Telescope images. We detect CO emission in five at high signal-to-noise
ratio with the remaining two only faintly detected. All CO emission is
coincident with the dust and is in dynamically cold rotation. Four ETGs show
evidence of rapid central rotation; these are prime candidates for
higher-resolution ALMA observations to measure the black hole masses. In this
paper we focus on the molecular gas and continuum properties. Total gas masses
and H$_2$ column densities for our five CO-bright galaxies are on average
$\sim10^8$ $M_\odot$ and $\sim10^{22.5}$ cm$^{-2}$ over the $\sim$kpc-scale
disks, and analysis suggests that these disks are stabilized against
gravitational fragmentation. The continuum emission of all seven galaxies is
dominated by a central, unresolved source, and in five we also detect a
spatially extended component. The $\sim$230 GHz nuclear continua are modeled as
power laws ranging from $S_\nu \sim \nu^{-0.4}$ to $\nu^{1.6}$ within the
observed frequency band. The extended continuum profiles of the two
radio-bright (and CO-faint) galaxies are roughly aligned with their radio jet
and suggests resolved synchrotron jets. The extended continua of the CO-bright
disks are coincident with optically thick dust absorption and have spectral
slopes that are consistent with thermal dust emission.
