Detecting the relativistic galaxy bispectrum. (arXiv:1911.02398v1 [astro-ph.CO])

<a href="http://arxiv.org/find/astro-ph/1/au:+Maartens_R/0/1/0/all/0/1">Roy Maartens</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jolicoeur_S/0/1/0/all/0/1">Sheean Jolicoeur</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Umeh_O/0/1/0/all/0/1">Obinna Umeh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Clarkson_C/0/1/0/all/0/1">Chris Clarkson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camera_S/0/1/0/all/0/1">Stefano Camera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Weerd_E/0/1/0/all/0/1">Eline M. De Weerd</a>

The Fourier-space galaxy bispectrum is complex, with the imaginary part

arising from leading-order relativistic corrections in redshift space. The

detection of the imaginary part of the bispectrum is potentially a smoking gun

signal of relativistic corrections. We investigate whether next-generation

spectroscopic surveys could make such a detection. For a Stage IV spectroscopic

$Halpha$ 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.

The Fourier-space galaxy bispectrum is complex, with the imaginary part

arising from leading-order relativistic corrections in redshift space. The

detection of the imaginary part of the bispectrum is potentially a smoking gun

signal of relativistic corrections. We investigate whether next-generation

spectroscopic surveys could make such a detection. For a Stage IV spectroscopic

$Halpha$ 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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