Correlated and coincident noise in Einstein Telescope's triangular configuration
The Einstein Telescope (ET) is a proposed underground infrastructure in Europe to host future generations of gravitational-wave (GW) detectors. Two configurations are under investigation. The first is the two-site solution with an L-shape detector at each site similar to the LIGO configuration. The second configuration is the single-site triangular detector. While numerous analyses over the last decade have already proven that the distributed network of GW detectors is the scientifically preferred solution, it was also argued that the advantage might not be decisive enough to dismiss ET's triangle configuration. The modeling of aspects such as noise correlations in these configurations has only been treated superficially in the past. In this article, we introduce a time-domain simulation of environmental noises in the ET triangle using available data from ET's candidate sites. We simulate and analyze correlated environmental noise as well as coincident glitches produced by transients in the environmental fields. We find that these features pose an important limitation to the observational capabilities of the ET triangle and limit the utility of its null stream.