2010ApJ...709L..70G

Until now, the known sources in the Galactic center with sufficiently smooth spectra and of sufficient brightness to be suitable for high-resolution infrared absorption spectroscopy of interstellar gas occupied a narrow range of longitudes, from the central cluster of hot stars to approximately 30 pc east of the center. In order to more fully characterize the gas within the r ∼ 180 pc central molecular zone, it is necessary to find additional such sources that cover a much wider longitudinal range of sightlines. We are in the process of identifying luminous dust-embedded objects suitable for spectroscopy within 1.{fdg}2 in longitude and 0.{fdg}1 in latitude of Sgr A* using the Spitzer GLIMPSE and the Two Micron All Sky Survey catalogs. Here we present spectra of H⁺₃ and CO toward two such objects, one located 140 pc west of Sgr A*, and the other located on a line of sight to the Sgr B molecular cloud complex 85 pc to the east of Sgr A*. The sightline to the west passes through two dense clouds of unusually high negative velocities and also appears to sample a portion of the expanding molecular ring. The spectra toward Sgr B reveal at least 10 absorption components covering over 200 km/s and by far the largest equivalent width ever observed in an interstellar H⁺₃line; they appear to provide the first near-infrared view into that hotbed of star formation.