Discovery of Massive Young Stellar Objects in the Galactic Center with Warm CO 2 Gas Absorption Deokkeun An (IPAC/Caltech) Solange Ramirez (IPAC/Caltech) Kris Sellgren (Ohio State U.) et al., 2009, ApJL, submitted

Galactic Center: Central Molecular Zone = central ~200 pc Star formation conditions unique because tidal shear, high gas pressure Evidence for recent star formation: Compact H II regions Young star clusters (1—8 Myr old) Search for candidate Young Stellar Objects (YSOs) with Spitzer IR images + Spitzer IR spectra

Sgr B2 Sgr C Sgr B1 Quintuplet Cluster Central Cluster + Sgr A* Arches Cluster 280 pc

Image Courtesy: NASA / JPL-Caltech

SSTGC

Warm molecular gas in massive YSO in the Galactic Center Deokkeun An, Ramirez, Sellgren, et al. ApJL, submitted Warm C 2 H 2 HCN CO 2 gas (absence of [Ne III] gas)

Fitting CO 2 ice profiles in GC YSOs with lab spectra “Shoulder” seen in CH 3 OH- rich ices

Gas-Phase Absorption from C 2 H 2, HCN, CO 2 GC YSO model fits: T = 100—400 K X(HCN) = 2—70 x10 -7 Sgr B2: T = 100—200 K X(HCN) = 0.2—0.7 x10 -7

Conclusions: Spectra of GC YSO candidates show warm CO 2, HCN, C 2 H 2 gas in absorption Spectra also show solid-phase CO 2, H 2 O, silicate dust CO 2 ice profile suggestive of high CH 3 OH ice abundance Molecular abundances comparable to other massive YSOs, much larger than towards Sgr B2 or TMC-1

Collaborators: Adwin Boogert (Caltech) Richard Arendt (NASA/Goddard) Angela Cotera (SETI Institute) Thomas Robitaille (St. Andrews U.) Mathias Schultheis (Besancon Obs.) Howard Smith (CFA) Susan Stolovy (SSC/Caltech)

+ = SSTGC = SSTGC Sgr B2 3.6 cm continuum Mehringer et al 1993 Sgr B2 (N) Sgr B2(M)

X = SSTGC Box = H 2 O maser + = OH maser 3 cm continuum Forster & Caswell (2000)

+ = SSTGC = SSTGC Sgr B2 CH 3 OH Jones et al 2008 S M N

+ = SSTGC = SST Sgr B2 1.3 cm continuum Gaume et al 1995 Sgr B2(M) Sgr B2 (N)