We present Atacama Large Millimeter/submillimeter Array observations of the GQ Lup system, a young Sun-like star with a substellar-mass companion in a wide-separation orbit. These observations of 870 mu m continuum and CO J = 3-2 line emission with beam size similar to 0."3 (similar to 45 au) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The circumprimary dust disk is compact with an FWHM of 59 +/- 12 au, while the gas has a larger extent with a characteristic radius of 46.5 +/- 1.8 au. By forward-modeling the velocity field of the circumprimary disk based on the CO emission, we constrain the mass of GQ Lup. A to be M-* = (1.03 +/- 0.05) * (d/156 pc) M-circle dot, where d is a known distance, and determine that we view the disk at an inclination angle of 60 degrees 5 +/- 0 degrees 5 and a position angle of 346 degrees +/- 1 degrees. The 3s upper limit on the 870 mu m flux density of any circumplanetary disk associated with GQ Lup b of <0.15 mJy implies an upper limit on the dust disk mass of <0.04M(circle dot) for standard assumptions about optically thin emission. We discuss proposed mechanisms for the formation of wide-separation substellar companions given the non-detection of circumplanetary disks around GQ Lup b and other similar systems.

Multi-wavelength observations provide a complementary view of the formation of young, directly imaged planetmass companions. We report the ALMA 1.3 mm and Magellan adaptive optics H alpha, i', z', and YS observations of the GQ Lup system, a classical T Tauri star with a 10-40 M-Jup substellar companion at similar to 110 au projected separation. We estimate the accretion rates for both components from the observed Ha fluxes. In our similar to 0.'' 05 resolution ALMA map, we resolve GQ Lup A's disk in the. dust continuum, but no signal is found from the companion. The disk is compact, with a radius of similar to 22 au, a dust mass of similar to 6M(circle plus), an inclination angle of similar to 56 degrees, and a very flat surface density profile indicative of a radial variation in dust grain sizes. No gaps or inner cavity are found in the disk, so there is unlikely a massive inner companion to scatter GQ Lup B outward. Thus, GQ Lup B might have formed in situ via disk fragmentation or prestellar core collapse. We also show that GQ Lup A's disk is misaligned with its spin axis, and possibly with GQ Lup B's orbit. Our analysis on the tidal truncation radius of GQ Lup A's disk suggests that GQ Lup B's orbit might have a low eccentricity.