by
Maryon Ahrens(Stockholm University, Department of Physics)
→
Europe/Stockholm
A5:1041
A5:1041
Description
Peculiar motion is motion superimposed on the motion acquired from the expansion of the universe. When we go backwards in time the peculiar speed among galaxies is increased. This situation reminds of a contracting ideal gas in which the kinetic energy among the constituents of the gas is increased. Since the age of the universe is finite there is a maximum distance that the galaxies have travelled since the time for the Big Bang. This distance can be seen as a horizon, called the matter horizon, analogue to the particle horizon for massless particles.
In this thesis we derive the differential equations governing the time development of straight line peculiar motion and solve these equations for both geodesic motion and when friction with the cosmic microwave background is included. We search for measurable model dependent quantities in the hope that such quantities can be compared with observations.
The result is that, while the peculiar motion as a function of redshift is not a model dependent quantity in the friction free case, it is when friction is included (even though the effect when we consider friction with the cosmic microwave background probably is to small to be observable). Also, the distance travelled is a model dependent quantity in both the friction free case and with friction added.
There is therefore good motivation to refine the theory for peculiar motion and the matter horizon and the investigation done in this thesis should serve as a steady platform for future projects to build upon.
