Investigating the XENON1T Low-Energy Electronic Recoil Excess Using NEST

The search for dark matter, the missing mass of the universe, is one of the most active fields of study within particle physics. The XENON1T experiment recently observed a 3.5{\sigma} excess consistent with solar axions, a possible dark matter candidate. Here we utilize the Noble Element Simulation Technique (NEST) software to model the XENON1T detector, and reproduce the excess. We report that, despite a detector efficiency modeling systematic, and non-ideal energy reconstruction sub-keV, the XENON1T excess cannot be explained by any simple detector parameter mismatch. However, using NEST, we can reproduce their excess in multiple unique ways, most easily via the addition of 31\pm11 ^{37}Ar decays. Moreover, this results in new modified background models, reducing the significance of the excess to only 1.5-2{\sigma}. This is an independent confirmation that the XENON1T excess appears to be a real effect, but that it can be explained with more mundane, known physics.