Infrared-excess Source DSO/G2 Near the Galactic Center: Theory vs. Observations

TL;DR

This study supports the hypothesis that the DSO/G2 near the Galactic Center is a dust-enshrouded young star undergoing accretion, based on spectral observations that contradict the core-less cloud model.

Contribution

The paper provides observational evidence favoring the young star model over the cloud hypothesis for DSO/G2, highlighting its compact emission and accretion signatures.

Findings

DSO/G2 remains spatially compact before and after peribothron.

Emission line profiles are consistent with a young star, not a core-less cloud.

Large line width indicates active accretion from circumstellar material.

Abstract

Based on the monitoring of the Dusty S-cluster Object (DSO/G2) during its closest approach to the Galactic Center supermassive black hole in 2014 and 2015 with ESO VLT/SINFONI, we further explore the model of a young, accreting star to explain observed spectral and morphological features. The stellar scenario is supported by our findings, i.e. ionized-hydrogen emission from the DSO that remains spatially compact before and after the peribothron passage. The detection of DSO/G2 object as a compact single-peak emission-line source is not consistent with the original hypothesis of a core-less cloud that is necessarily tidally stretched, hence producing a double-peak emission line profile around the pericentre passage. This strengthens the evidence that the DSO/G2 source is a dust-enshrouded young star that appears to be in an accretion phase. The infall of material from the circumstellar disc onto the stellar surface can contribute significantly to the emission of Br$\gamma$ line as well as the observed large line width of the order of 10 angstrom.