The dipole of the galaxy bispectrum

Chris Clarkson, Eline M. de Weerd, Sheean Jolicoeur, Roy Maartens, Obinna Umeh

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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.
Original languageEnglish
Pages (from-to)L101-L104
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date6 May 2019
Publication statusPublished - Jun 2019


  • astro-ph.CO
  • gr-qc
  • cosmology: theory
  • cosmology: large-scale structure of Universe
  • RCUK
  • STFC
  • ST/P000592/1
  • ST/N000668/1


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