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 more than 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.
@article{arxiv.1812.09512,
title = {The dipole of the galaxy bispectrum},
author = {Chris Clarkson and Eline M. de Weerd and Sheean Jolicoeur and Roy Maartens and Obinna Umeh},
journal= {arXiv preprint arXiv:1812.09512},
year = {2019}
}
Comments
5 pages, 2 figures. v2 has slight changes to the figures and is the version to appear in MNRAS Letters