  We present observations of the central 9 kpc of the Antennae merger (NGC
4038/9) at 55 pc resolution in the CO 2-1 line obtained with the Atacama Large
Millimeter/submillimeter Array (ALMA). We use a pixel-based analysis to compare
the gas properties in the Antennae to those in 70 nearby spiral galaxies from
the PHANGS-ALMA survey, as well as the merger and nearest luminous infrared
galaxy NGC 3256. Compared to PHANGS galaxies at matched spatial resolution, the
molecular gas in the Antennae exhibits some of the highest surface densities,
velocity dispersions, peak brightness temperatures, and turbulent pressures.
However, the virial parameters in the Antennae are consistent with many of the
PHANGS galaxies. NGC 3256 has similar gas surface densities but higher nuclear
velocity dispersions than the Antennae, as well as higher system-wide peak
brightness temperatures and virial parameters. NGC 3256 is at a later stage in
the merging process than the Antennae, which may result in more intense
merger-driven gas flows that could drive up the turbulence in the gas. The high
virial parameters in NGC 3256 may indicate that this increased turbulence is
suppressing future star formation as NGC 3256 moves out of the starburst phase.
In comparison, the relatively normal virial parameters in the Antennae may
imply that it is about to undergo a new burst of star formation.
