This project would involve setting up a large (>100 Mpc) cosmological simulation in the Modified Gravity (MOND) framework, but supplemented with 11 eV sterile neutrinos to make up the same total dark energy and matter density as in the Lambda Cold Dark Matter (ΛCDM) cosmology.
The simulations would build on existing simulations of the sterile neutrino + MOND framework (e.g. Katz+ 2013) that obtained promising results. The project would use the existing Phantom of RAMSES code (Nagesh+ 2021) in Modified Gravity combined with Newtonian initial conditions at a redshift of about 200, when MOND effects should be negligible. Structure formation would proceed more rapidly than in ΛCDM on large scales, while on small scales the lack of cold dark matter would be compensated by an enhanced long range gravity law.
The aim would be to look for (1) analogues to the El Gordo-like massive galaxy cluster pair and (2) analogues to the local 300 Mpc KBC void; both of these rule out ΛCDM above 6σ significance (Haslbauer+ 2020, Asencio+ 2021). More generally, the results of the simulations would be compared with a range of observations, e.g. the cluster mass function within 500 Mpc of observers like us in a low-density region (void).
The project would be supervised by Dr Hongsheng Zhao and closely guided by Dr Indranil Banik. It would be in collaboration with the dynamics group in Bonn, which has long been interested in similar problems and has researchers working on a similar area. The successful candidate should demonstrate a willingness to think outside the box of ΛCDM, which has revealed cracks on nearly all astrophysical scales where tests have been possible so far.
See a recent review by Banik & Zhao (https://arxiv.org/abs/2110.06936) and a recent invited lecture overviewing Modified Gravity (https://www.youtube.com/watch?v=jL09gRe1q7s).
This project would be eligible for funding including: Science and Technology Facilities Council (STFC) scholarships administered by the University. Note: Candidates will be subject to competition with students on other projects, so it is possible that no candidate will be selected for this position such that it remains unfilled for the current application round.
A list of all astrophysics PhD projects on offer at Saint Andrews is available here, along with contact details and information on how to apply: