First Spectroscopic Identification of Massive Young Stellar Objects in the Galactic Center

TL;DR

This study presents the first spectroscopic confirmation of massive young stellar objects in the Galactic Center, revealing molecular absorption features indicative of their youth and dense environments.

Contribution

It provides the first spectroscopic identification of massive YSOs in the Galactic Center using infrared observations.

Findings

Detection of gas-phase absorption features from CO2, C2H2, and HCN.

Observation of broad CO2 ice absorption with a double-peaked structure.

Identification of these objects as massive YSOs based on spectral features.

Abstract

We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO2 (15.0um), C2H2 (13.7um) and HCN (14.0um). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15um CO2 ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH3OH-rich ice grains, and is similar to those found in other known massive YSOs. Our IRS observations demonstrate the youth of these objects, and provide the first spectroscopic identification of massive YSOs in the Galactic Center.