Pritha Paul and Chris Clarkson tell us about their work, along with Roy Maartens, delving very deeply into standard observational cosmology. Specifically, they have looked at relativistic effects in the four point function/trispectrum of galaxy positions.
This might sound crazy and masochistic, but there are big rewards. On large enough scales, the relativistic effects start to grow, and tantalisingly, once one takes into account both relativistic effects and the observational effects of observing in redshift space, a parity violating signal emerges in both the bispectrum and trispectrum on large scales. This is very interesting given the possible observations of parity violation in the four point function of galaxy positions (i.e. Fourier transform of the trispectrum).
There are reasons to suspect the effect Pritha, Chris and Roy have uncovered within standard cosmology couldn’t be the thing potentially observed in the four point function, however it is possible to at least tell a story about how the one effect might show up in the other observation. Time will tell whether they are indeed related.
Irrespective of that, the result is still interesting as it is likely that Euclid and/or SKA will be able to spot this signal, thus detecting the effects of relativity within the large scale structure.
Pritha: https://www.qmul.ac.uk/spcs/staff/research-students/profiles/ppaul.html
Chris: https://www.qmul.ac.uk/spcs/staff/academics/profiles/chrisclarkson.html
Cosmology Talks 