Massive binaries in the vicinity of Sgr A*

TL;DR

This study identifies and characterizes multiple massive binary systems near Sgr A*, constrains their binary fraction, and finds it comparable to that in dense star clusters, enhancing understanding of stellar populations near the Galactic Center.

Contribution

The paper reports the discovery of two new binaries near Sgr A* and constrains the binary fraction, showing it is similar to that in dense star clusters.

Findings

Three confirmed OB/WR binaries within 0.2 pc of Sgr A*

Binary fraction estimated at approximately 27% with confidence intervals

Eclipsing binary fraction consistent with local OB star clusters

Abstract

A long-term spectroscopic and photometric survey of the most luminous and massive stars in the vicinity of the super-massive black hole Sgr A* revealed two new binaries; a long-period Ofpe/WN9 binary, GCIRS 16NE, with a modest eccentricity of 0.3 and a period of 224 days and an eclipsing Wolf-Rayet binary with a period of 2.3 days. Together with the already identified binary GCIRS 16SW, there are now three confirmed OB/WR binaries in the inner 0.2\,pc of the Galactic Center. Using radial velocity change upper limits, we were able to constrain the spectroscopic binary fraction in the Galactic Center to $F_{\rm SB}=0.27^{+0.29}_{-0.19}$ at a confidence level of 95%, a massive binary fraction similar to that observed in dense clusters. The fraction of eclipsing binaries with photometric amplitudes $\Delta m>0.4$ is $F^{\rm GC}_{\rm EB}=3\pm2%$, which is consistent with local OB star clusters ($F_{\rm EB}=1%$). Overall the Galactic Center binary fraction seems to be close to the binary fraction in comparable young clusters.