Speaker:	Lea Harscouet (U of Oxford)
Title:	Cross-correlations of LSS tracers with projected bispectra
Date (JST):	Tue, Sep 09, 2025, 11:00 - 12:00
Place:	Seminar Room A
Abstract:	The study of correlators beyond the power spectrum has been hampered by the increased complexity of bispectrum estimators: the high dimensionality of the data vector, complex covariance estimation, and overall high computational cost make its use prohibitive, despite its potential for extracting non-Gaussian information from LSS fields. The Filtered-Squared Bispectrum (FSB) is a novel projected bispectrum estimator which addresses most of these issues. It consists in taking the power spectrum of a field and a version of the field filtered on a range of harmonic scales, then squared in configuration space. Because the FSB reinterprets the bispectrum as a power spectrum, we're also able to recycle most of the infrastructure built around power spectrum measurements – including covariance matrix estimation! We provide a fully analytical and model-independent way to estimate the FSB covariance. The FSB can be applied to the study of cross-correlations of LSS tracers; today I will show how we can build a full inference pipeline to derive additional constraints on bias and cosmological parameters. If there is time, I will also tell you about how to turn a measurement of the Sunyaev-Zeldovich effect into an FSB!

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