Modal compression of the redshift-space galaxy bispectrum

Abstract We extend the modal decomposition method, previously applied to compress information in real-space bispectrum, anisotropic redshift-space galaxy bispectrum. In method approach, bispectrum is expanded on a basis of smooth functions triangles and their orientations, such that set expansion coefficients can capture assume reference survey compute Fisher forecasts for compressed two other decompositions literature, one based (single) spherical harmonics another tripolar harmonics. each case, we compare forecasted constraints from statistic with full, uncompressed which includes all orientations. Our main result three compression methods achieve good recovery full content but approach achieves this most efficiently: only 14 (42) are necessary obtain within 10 (2) per cent result. The next efficient harmonics, while harmonic multipoles least efficient.