Jet- and Wind-Driven Ionized Outflows in the Superbubble and Star-Forming Disk of NGC 3079

Abstract

HST WFPC2 images are presented that span the inner 19 kpc diameter of the edge-on spiral galaxy NGC 3079; they are combined with ground-based Halpha+[N II] Fabry-Perot spectra and VLA images of radio polarization vectors and rotation measures. Ionized gas filaments within 9 kpc diameter project ~3 kpc above the disk, with the brightest forming the 1 kpc diameter superbubble. They are often resolved into strands ~0."3 (25 pc) wide which emerge from the nuclear CO ring as five distinct gas streams with velocity gradients and dispersions of hundreds of km/s. One stream flows for 250 pc and aligns with the VLBI-scale radio jet, the other four are not connected to the jet, instead curving to the vertical 0.6 kpc above the galaxy disk, then dispersing in a spray of droplets each with ionized mass ~1000 sqrt(f) Msun (volume filling factor f > 0.003 from our data). Shredded clumps of disk gas form a similar structure in hydro models of a galaxy-scale wind. The pattern of magnetic fields and the gas kinematics also suggest a wind of mechanical luminosity 10^43 erg/s that has stagnated in the galaxy disk at radius ~800 pc, flared to larger radii with increasing height as the balancing ISM pressure reduces above the disk, and entrained dense clouds into a vortex. Total KE and momentum of the filaments are (0.4-5)x10^55 sqrt(f) ergs and (1.6-6)x10^47 sqrt(f) dyne s. A star-forming complex elsewhere in the galaxy shows a striking spray of linear filaments that extend for hundreds of parsecs.