Simulations of the universe using modified newtonian dynamics
Final Report Abstract
Despite the generally accepted success of the cold dark matter cosmology the model still inhibits a number of serious deviations from observations, especially on sub-galactic scales. Moreover, none of the putative dark matter particle candidates have yet been detected. Modified Newtonian dynamics (MOND) is a modification to Newton's second law of motion capable of explaining most of the observations without the need for dark matter. The main objective of this proposal was to perform fully self-consistent cosmological simulations of the formation and evolution of structures in the Universe under the infiuence of this alternative theory. We wrote a novel numerical solver for MOND in analogy to relaxation methods for solving Poisson's equation. The major obstacle in that regards was the non-linearity of this equation which rendered standard solution techniques useless. We had to utilize an iterative relaxation method that guarantees convergence to the physically relevant solution. Once this had been accomplished - within the first two years of the project - we had the tools at hand to utilize our new code to investigate a series of astrophysically interesting questions, like the likelihood of high-speed encounters of galaxies, a Newtonian interpretation of MONDian efiects, and the stability of triaxial systems. Surprisingly, MOND increases the likelihood for high-speed encounters are by a factor of four, an advantage for modeling relevant observations of cluster encounters. A detailed analysis of the bullet clusters still cannot fully explain the offset of the baryonic and the gravitational centers. We provide triaxial galaxy models in MOND with properties concerning the radial anisotropy profile and a reduction of the central density that well compares with properties of observed elliptical galaxies.
Publications
- 2008, MNRAS, 391, 1778-1790 "Cosmological structure formation under MOND: a new numerical solver for Poisson's equation"
Llinares C , Knebe A., Zhao H.-S.
- 2009, ApJ, 703, 2285-229 "On the separation between baryonic and dark matter: evidence for phantom dark matter?"
Knebe A., Llinares C , Wu X., Zhao H.-S.
- 2009, ApJ, L145-L148 "Physics of galactic colliders: high-speed satellites in \CDM vs. MONDian cosmology"
Llinares C , Zhao H.-S., Knebe A.
- 2009, MNRAS, 396, 109-120 "N-body simulations for testing the stability of triaxial galaxies in MOND"
Wu X., Zhao H.-S., Wang Y., Llinares C , Knebe A.
