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arXiv · 1911.02398

Detecting the relativistic galaxy bispectrum

Roy Maartens·Sheean Jolicoeur·Obinna Umeh·Eline M. De Weerd·Chris Clarkson·Stefano Camera
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Abstract

The Fourier-space galaxy bispectrum is complex, with the imaginary part arising from leading-order relativistic corrections, due to Doppler, gravitational redshift and related line-of-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 next-generation spectroscopic surveys could make such a detection. For a Stage IV spectroscopic $H\alpha$ survey similar to Euclid, we find that the cumulative signal to noise of this relativistic signature is $\mathcal{O}(10)$. 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.

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Roy Maartens, Sheean Jolicoeur, Obinna Umeh, Eline M. De Weerd, Chris Clarkson, Stefano Camera. 2019-11-06. Detecting the relativistic galaxy bispectrum. https://doi.org/10.1088/1475-7516%2F2020%2F03%2F065

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