Detection of polarized continuum emission of the Dusty S-cluster Object (DSO/G2)

TL;DR

This study uses near-infrared polarimetric imaging to reveal the Dusty S-cluster Object's intrinsic polarization and geometry, suggesting it is a pre-main-sequence star with a dusty envelope near the Galactic center.

Contribution

First polarimetric analysis of DSO providing constraints on its geometry and nature, indicating it is a polarized pre-main-sequence star with a dusty envelope.

Findings

DSO is intrinsically polarized with ~30% polarization degree.

Polarization angle varies as DSO approaches Sgr A*.

DSO's properties suggest a pre-main-sequence star embedded in a dusty envelope.

Abstract

A peculiar source in the Galactic center known as the Dusty S-cluster Object (DSO/G2) moves on a highly eccentric orbit around the supermassive black hole with the pericenter passage in the spring of 2014. Its nature has been uncertain mainly because of the lack of any information about its intrinsic geometry. For the first time, we use near-infrared polarimetric imaging data to obtain constraints about the geometrical properties of the DSO. We find out that DSO is an intrinsically polarized source, based on the significance analysis of polarization parameters, with the degree of the polarization of $\sim 30\%$ and an alternating polarization angle as it approaches the position of Sgr A*. Since the DSO exhibits a near-infrared excess of $K_{\rm s}-L'>3$ and remains rather compact in emission-line maps, its main characteristics may be explained with the model of a pre-main-sequence star embedded in a non-spherical dusty envelope.