The dipole of the galaxy bispectrum. (arXiv:1812.09512v1 [astro-ph.CO])
<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:+Weerd_E/0/1/0/all/0/1">Eline Maaike de Weerd</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:+Maartens_R/0/1/0/all/0/1">Roy Maartens</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Umeh_O/0/1/0/all/0/1">Obinna Umeh</a>

The bispectrum will play an important role in future galaxy surveys. On large
scales it is a key probe for measuring primordial non-Gaussianity which can
help differentiate between different inflationary models and other theories of
the early universe. On these scales a variety of relativistic effects come into
play once the galaxy number-count fluctuation is projected onto our past
lightcone. We show for the first time that the leading relativistic correction
from these distortions in the galaxy bispectrum generates a significant dipole,
mainly from relativistic redshift space distortions. The amplitude of the
dipole can be 10% of the monopole even on equality scales. Such a dipole is
absent in the Newtonian approximation to the redshift space bispectrum, so it
offers a clear signature of relativistic effects on cosmological scales in
large scale structure.

The bispectrum will play an important role in future galaxy surveys. On large
scales it is a key probe for measuring primordial non-Gaussianity which can
help differentiate between different inflationary models and other theories of
the early universe. On these scales a variety of relativistic effects come into
play once the galaxy number-count fluctuation is projected onto our past
lightcone. We show for the first time that the leading relativistic correction
from these distortions in the galaxy bispectrum generates a significant dipole,
mainly from relativistic redshift space distortions. The amplitude of the
dipole can be 10% of the monopole even on equality scales. Such a dipole is
absent in the Newtonian approximation to the redshift space bispectrum, so it
offers a clear signature of relativistic effects on cosmological scales in
large scale structure.

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