Mitigating contamination in LSS surveys: a comparison of methods

ABSTRACT Future large-scale structure surveys will measure the locations and shapes of billions galaxies. The precision such catalogues require meticulous treatment systematic contamination observed fields. We compare several existing methods for removing systematics from galaxy clustering measurements. show how all methods, including popular pseudo-C? Mode Projection Template Subtraction can be interpreted under a common regression framework use this to suggest improved estimators. designed mitigate in power spectrum used produce clean maps, which are necessary cosmological analyses beyond spectrum, we extend current treat next-order multiplicative maps spectra, reduced errors $\Delta \chi ^2_{\rm C_\ell }\simeq 10$ ? 1 simulated analyses. Two new mitigation proposed, incorporate desirable features state-of-the-art while being simpler implement. Investigating performance on set measurements Year 5 Dark Energy Survey, test their robustness various analysis cases. Our proposed spectra when compared requiring almost no user tuning. end with recommendations future surveys, note that presented generally applicable distribution any field spatial systematics.