Camera, StefanoMaartens, RoySantos, Mario G.2015-10-282015-10-282015Camera, S., et al. (2015). Einstein's legacy in galaxy surveys. Monthly Notices of the Royal Astronomical Society: Letters, 451(1): L80-L841365-2966http://hdl.handle.net/10566/1937http://dx.doi.org/10.1093/mnrasl/slv069This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society Letters following peer review. The version of record Camera, S., et al. (2015). Einsteins legacy in galaxy surveys. Monthly Notices of the Royal Astronomical Society: Letters, 451(1):L80-L84 is available online at: http://dx.doi.org/10.1093/mnrasl/slv069.Non-Gaussianity in the primordial fluctuations that seeded structure formation produces a signal in the galaxy power spectrum on very large scales. This signal contains vital information about the primordial Universe, but it is very challenging to extract, because of cosmic variance and large-scale systematics especially after the Planck experiment has already ruled out a large amplitude for the signal. Whilst cosmic variance and experimental systematics can be alleviated by the multi-tracer method, we here address another systematic—introduced by not using the correct relativistic analysis of the power spectrum on very large scales. In order to reduce the errors we need to include measurements on the largest possible scales. Failure to include the relativistic effects on these scales can introduce significant bias in the best-fit value from future galaxy surveys.enThis is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society Letters following peer review. The version of record Camera, S., et al. (2015). Einsteins legacy in galaxy surveys. Monthly Notices of the Royal Astronomical Society: Letters, 451(1):L80-L84 is available online at: http://dx.doi.org/10.1093/mnrasl/slv069.CosmologyLarge-scale structure of the universeEarly Universe cosmological parametersRadio linesGalaxiesRelativistic processesArticle