研究期間：10108~10207;Abstract: This proposal is a study on the MOdified Newtonian Dynamics (MOND) as an alternative to dark matter. It contains two parts. In the first part, we want to apply relativistic version of MOND to gravitational lensing, and in the second part we want to study the structure of a stellar system and its destruction by tidal interaction. The first one mainly uses observational data to constraint different models, while the second one relies on simulations. Discrepancy between observed acceleration in many astrophysical objects and Newtonian dynamics (or general relativity) invokes different interpretations. Basically, both dark matter dynamics and MOND can be considered as an algorithm to interpret the observational data. MOND proposes that at small acceleration the interaction is stronger than Newtonian dynamics. In our opinion, MOND is far more successful than dark matter in galaxy scales. As in other theories, MOND has some free parameters and functions. The most important ones are the small acceleration parameter and the interpolation function (which connects Newtonian regime and MONDian regime). Small acceleration parameter can be fixed in deep MOND regime (i.e., the acceleration is very small), such as rotation curve of spiral galaxies. To probe the interpolation function, one needs to go to intermediate MOND regime. We find that strong gravitational lensing often happens in intermediate MOND regime. We propose to use TeVeS (Tensor-Vector-Scalar gravity theory, a relativistic version of MOND) to study strong lensing systems. We are interested in elliptical galaxies acting as lenses, in particular, those with dispersion velocity measurement. Under the hypothesis of a mass fundamental plane among elliptical galaxies, we can constraint the interpolation function. We are also keen on Einstein rings as they provide a unique scale for us to discuss those interpolation functions in the intermediate MOND regime. Moreover, we would like to work on microlensing and weak lensing in MOND. A byproduct of this part is the distribution of the (baryonic) mass-to-light ratio of elliptical galaxies. The structure of a stellar system and its destruction during an encounter with a larger object should be different from Newtonian case. MOND can be interpreted as a modified gravity theory where the potential is described by a modified Poisson equation. We propose to develop an N-body code which incorporates MOND correctly. The code will comprise two parts, the potential solver and the N-body part. We would like to construct some models of polytropes and study the detail dynamics of tidal disruption in MOND. We would like to see if MOND can explain the apparent scarcity of dwarf galaxies in our neighbourhood.
