Detecting the relativistic galaxy bispectrum
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing Ltd
Abstract
The Fourier galaxy bispectrum is complex, with the imaginary part arising from
leading-order relativistic corrections, due to Doppler, gravitational redshift and related lineof-sight effects in redshift space. The detection of the imaginary part of the bispectrum is
potentially a smoking gun signal of relativistic contributions. We investigate whether nextgeneration spectroscopic surveys could make such a detection. For a Stage IV spectroscopic
Hα survey similar to Euclid, we find that the cumulative signal to noise of this relativistic
signature is O(10). Long-mode relativistic effects couple to short-mode Newtonian effects
in the galaxy bispectrum, but not in the galaxy power spectrum. This is the basis for
detectability of relativistic effects in the bispectrum of a single galaxy survey, whereas the
power spectrum requires multiple galaxy surveys to detect the corresponding signal.
Description
Keywords
Cosmological parameters from LSS, Cosmological perturbation theory, Redshift surveys, Galaxy bispectrum, Relativistic
Citation
Maartens, R. et al. (2020). Detecting the relativistic galaxy bispectrum. Journal of Cosmology and Astroparticle Physics, 2020(03)