Large-scale structure formation in a one-dimensional Universe

A computer code to simulate the temporal evolution of overdensities in a one-dimensional Universe is presented. Its simplicity makes it suitable for didactic purposes. The formation of large-scale structures in this one-dimensional universe can be studied both in matter- or radiation-dominated eras. Since large-scale structures are already observed at z greater than or equal to 5, primordial dark matter overdensities delta(DM) larger than the observed baryonic delta(B) in the cosmic microwave background are required at z similar to 1000. This makes non-linear gravitational collapse at redshift z greater than or equal to 5 and the formation of the structures possible. Primordial perturbations delta(B) similar to 10(-5) do not leave the linear regime of growth without the aid of dark matter's potential wells. This code is suitable for commercial worksheets like MSExcel, StarOffice or OpenOffice.