A Warped Accretion Disk and Wide‐Angle Outflow in the Inner Parsec of the Circinus Galaxy

We present the first VLBI maps of H2O maser emission (lambda 1.3cm) in thenucleus of the Circinus Galaxy, constructed from data obtained with theAustralia Telescope Long Baseline Array. The maser emission traces a warped,edge-on accretion disk between radii of 0.11+/-0.02 and ~0.40 pc, as well as awide-angle outflow that extends up to ~1 pc from the estimated disk center. Thedisk rotation is close to Keplerian (v varies as 1/sqrt(r)), the maximumdetected rotation speed is 260 km/s, and the inferred central mass is 1.7+/-0.3x 10^6 solar masses. The outflowing masers are irregularly distributed aboveand below the disk, with relative outflow velocities up to ~+/-160 km/s,projected along the line of sight. The flow probably originates closer than 0.1pc to the central engine, possibly in an inward extension of the accretiondisk, though there is only weak evidence of rotation in the outward movingmaterial. We observe that the warp of the disk appears to collimate the outflowand to fix the extent of the ionization cone observed on larger angular scales.This study provides the first direct evidence (i.e., through imaging) of dusty,high-density, molecular material in a nuclear outflow <1 pc from the centralengine of a Seyfert galaxy, as well as the first graphic evidence that warpedaccretion disks can channel outflows and illumination patterns in AGN. Wespeculate that the same arrangement, which in some ways obviates the need for ageometrically thick, dusty torus, may apply to other type-2 AGN.Comment: To appear in The Astrophysical Journal (part 1), Volume 590, June 10, 2003. Five color figure