Supplementary Material for Extraterrestrial Axion Search with the Breakthrough Listen Galactic Center Survey  
I. Data Selection and Reduction  
II. Calibration  
III. Data Analysis  
IV. Shifted Down Binning Analysis  
V. Survival Function and Inspection of Remaining Excesses  
VI. Neutron Star Population Modeling  
VII. NS Signal Predictions and DM Interpretation  
VIII. Synthetic Signal Tests  