SpitzerIRS Observations of the Galactic Center: Shocked Gas in the Radio Arc Bubble

• DOI: 10.1086/522295
• Publication Date: 2007-12-05T07:08:24Z
• Authors: Janet P. Simpson; Sean W. J. Colgan; Angela S. Cotera; Edwin F. Erickson; David J. Hollenbach; Michael J. Kaufman; Robert H. Rubin
• Keywords: Line (geometry); Line-of-sight

We present Spitzer IRS spectra (R ~600, 10 - 38 micron) of positions in the Galactic Center (GC), all at same longitude and spanning plus/minus 0.3 degrees latitude. Our include Arches Cluster, Arched Filaments, regions near Quintuplet ``Bubble'' lying along line-of-sight as molecular cloud G0.11-0.11, diffuse interstellar gas higher latitudes. From measurements [O IV], [Ne II], III], [Si [S [Fe H_2 S(0), S(1), S(2) lines we determine excitation ionic abundance ratios. The Ne/H S/H ratios are ~ 1.6 times that Orion Nebula. main source is photoionization, with Cluster ionizing Filaments nearby lower latitudes including far side Bubble. In addition, strong shocks ionize to O^{+3} destroy dust grains, releasing iron into phase (Fe/H 1.3 10^{-6} Fe/H 8.8 Bubble). shock effects particularly noticeable center Bubble, but O$^{+3}$ positions. suggest due winds from Wolf-Rayet stars. On other hand, line can be explained multi-component models warm photodissociation without need for production shocks.