Detecting the relativistic dipole in galaxy clustering with DESI

26.09.2025 11:50 – 12:50

Understanding the accelerated expansion of the Universe remains one of the key challenges in cosmology. The main candidates explaining this observation without relying on a cosmological constant are dark energy and modifications of General Relativity. However, they both require robust tests on cosmological scales. The Dark Energy Spectroscopic Instrument (DESI) provides unprecedented precision in measuring galaxy clustering from spectroscopic data, enabling the detection of relativistic effects beyond the standard redshift-space distortions. In particular, such effects generate a dipole in the cross-power spectrum of two galaxy populations. Using mock catalogues of galaxies which mimic the DESI Bright Galaxy Survey, we analyse strategies to amplify the relativistic dipole by separating galaxies into bright and faint populations. While modelling the measured distortions proves to be non-trivial, our results indicate improved detectability of the dipole with fewer bright sources.

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Bâtiment: Ecole de Physique

EP234

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