Hubble Space Telescope Imaging of the Seyfert 2 Galaxy NGC 2110

Abstract

Hubble Space Telescope (HST) images of the Seyfert 2 galaxy NGC 2110 in the emission lines of [O III] λλ4959,5007 and Hα + [N II] λλ6548,6584 and the nearby continuum are presented. After deconvolution, the resolution of these images is ~0.1", corresponding to a linear scale of ~23 pc at the assumed distance (46.8 Mpc) to this galaxy. The dominant line emission is associated with a strongly curved, narrow, 1" (230 pc) long feature emanating from the nucleus to the north. The morphology of this feature suggests that it may represent gas flowing outward from the nucleus (perhaps as a "jet"). While this optical emission-line feature and the jetlike radio emission extend along a similar P.A., their detailed brightness distributions are loosely anticorrelated. In particular, there is no line emission associated with the off-nuclear 6 cm peaks and only weak radio emission along the optical "jet." On a larger scale, there is an S-shaped distribution of ionized gas (seen best in Hα) extending ~4" north and south of the nucleus. Ground-based kinematical data suggest this larger scale component represents normally rotating, ambient, interstellar gas photoionized by the central source. A continuum color map derived from HST observations shows evidence for an unresolved region (scale <23 pc) of very strong reddening at the location of the optical and radio nucleus. The location and size of the reddened region are consistent with obscuration by a dusty torus, but the observed reddening provides only a lower limit (A_v_ >= 4.6_-1.7_^+1.2^ mag) on the amount of obscuration to the nucleus. Nevertheless, this obscuration is sufficient to account for the "energy deficit" previously reported in this object.