On the Origins of Gaia-BH3: 3D Non-LTE Reanalysis of its Stellar Companion

In a paper by Balbinot et al. it is proposed that the Gaia BH3 binary system originates from the ED-2 disrupted stellar stream. While they provided strong kinematic evidence to support the claim, the chemical evidence displayed weaknesses. The aim of this project was to analyze the stellar ED-2 and companion star data used by Balbinot et al. in 1D LTE and 3D NLTE in order to confirm or deny the proposed origins. The data was analyzed through 1D LTE and 3D NLTE line-by-line scatter abundance plots and chemical abundance ratio plots. The abundance ratios of the stars were also compared to atomic diffusion models in order to determine whether potential abundance differences could be explained by atomic diffusion processes. The results showed that the abundance differences between the Gaia BH3 companion star and the ED-2 stars is significant even when analyzed in 3D NLTE. It was also determined that the abundance discrepancies are reduced but remain significant after considering atomic diffusion models from the literature. Stellar black hole formation theory presents us with scenarios that could potentially explain the origins of Gaia BH3, but we would need to know how the black hole originally formed. In conclusion, it was determined that according to the chemical compositions, it is unclear if Gaia BH3 in fact originates from the ED-2 stellar stream.