Constraints on a Putative Planet Sculpting the V4046 Sagittarii
  Circumbinary Disk
  We analyze the highest-resolution millimeter continuum and near-infrared
(NIR) scattered-light images presented to date of the circumbinary disk
orbiting V4046 Sgr, a ~20 Myr old actively accreting, close binary T Tauri star
system located a mere 72.4 pc from Earth. We observed the disk with the Atacama
Large Millimeter/submillimeter Array (ALMA) at 870-micron during Cycle 4, and
we analyze these data in conjunction with archival NIR (H band) polarimetric
images obtained with SPHERE/IRDIS on the ESO Very Large Telescope. At 0.3'' (20
au) resolution, the 870-micron image reveals a marginally resolved ring that
peaks at ~32 au and has an extension of ~ 90 au. We infer a lower limit on dust
mass of ~ 60.0 M_earth within the 870-micron ring, and confirm that the ring is
well aligned with the larger-scale gaseous disk. A second, inner dust ring is
also tentatively detected in the ALMA observations; its position appears
coincident with the inner (~14 au radius) ring detected in scattered light.
Using synthetic 870 micron and H-band images obtained from disk-planet
interaction simulations, we attempt to constrain the mass of the putative
planet orbiting at 20 au. Our trials suggest that a circumbinary Jovian-mass
planet may be responsible for generating the dust ring and gap structures
detected within the disk. We discuss the longevity of the gas-rich disk
orbiting V4046 Sgr in the context of the binary nature of the system.
