The galactic center lobe: new 14GHz GBT observations

Outflows from nuclear winds are observed in dozens of galaxies and can have profound effects on galactic evolution and the state of the intergalactic medium. Nuclear winds may have different origin mechanisms, such as starbursts or accretion on the central engine, but regardless of how the energy is deposited into the nucleus, outflow from the expansion of very hot gas can result in a wind-blown superbubble. Periods of previous outflow in our own Galaxy have resulted in several structures interpreted as superbubbles; the Galactic Center Lobe (GCL), a 150pc-scale open, omega-shaped projection perpendicular to the Galactic Plane, more-or-less centered on the Galactic Center, is one such structure. We have observed the GCL at 14GHz (2cm) with the Robert C. Byrd 100m Green Bank Telescope (GBT) with the original intent to obtain a more definitive constraint on the energetics of the GCL, but in the course of our observations have concluded that the walls of the GCL itself are composed of two likely unrelated structures. We reduce and analyze new GBT data with new software and use a novel filtering technique to analyze existing multi-band data from the Nobeyama Radio Observatory 45m telescope, the NRAO Very Large Array, the Spitzer Space Telescope, and the Chandra X-ray Observatory. We propose that the nuclear outflow is manifested not in both spurs of the GCL, but in the western spur of the GCL and a new structure observed above the SgrB-complex. Additionally, the eastern wall of the GCL is interpreted as a jet-like extension of the Galactic Center Arc, and is seen to be interacting with the Double Helix Nebula in a manner inconsistent with a limb-brightened shell wall