Towards large mass ratio binary black hole inspirals

The growing catalog of gravitational wave detections by the LIGO-Virgo-KAGRA collaboration has moved us into a new era of gravitational wave astronomy. With additional, even more sensitive detectors such as LISA, TianQin and Cosmic Explorer being planned, we can anticipate a growing need for highly accurate numerical simulations of binary compact object mergers in full general relativity. While current gravitational waveform libraries are largely sufficient for today's detectors, these future detectors will be sensitive to new frequency bands, higher signal-to-noise ratios, a larger variety of sources and will require yet higher accuracy waveforms. There will be a growing need to be able to better model challenging systems including binary black holes with large mass ratios, high spins and highly eccentric orbits. We describe progress in the development of the numerical code, Dendro-GR, as applied to some of these complications as well to binary systems in alternative gravity theories.