Structure Formation and the Evolution of the Universe

Astr112 Lab#5

Jacob Darby 36443458

6/5/2015

Structure FormationQuestion one a) Parameters are and

The simulation and observation do not match because both the values of cluster amplitude and dark matter density to match the actual observation. In terms of the histogram the dark matter density changes the maximum density that occurs, and shifts the graph to a higher range of densities. Thus increasing both the cluster amplitude and the dark matter density will give rise to a more defined simulation closer to that of the observation.

b) Parameters are and

The value for dark matter density is slightly too high in this simulation. This causes all of the normal matter to be attracted to the regions of higher density dark matter, causing the regions of normal matter to become denser also. All other variables fit well to the observation.

c) A positive cosmological constant results in a positive energy density which will drive a accelerating universe.

Evolution of the UniverseB1)

At time zero the slope of all three curves are the same this is because at the time the slope is based on experimental data. Everything that follows time zero is prediction of the evolution of the universe, it is only at time zero where the slope is actually been measured and has a known value.

B2)a) Slope of the line is

b) km/s/Mpc (approx)

c)

d)

B3)a)

b) A redshift of 5.5 corresponds to a look back time of 12.5Gyr.

B4)

Because the slope of the graph is greater at 20G/years then the Hubble parameter will be more positive giving an accelerating universe.

B5)

Age in case 1: 13.33 Giga yearsAge in case 2: 6.67 Giga yearsAge in case 3: 1.33 Giga years

When decreasing the mass density to =0.5 for H0=50, the curve age of the universe is larger. With these values the age of the universe is 15.07 Giga years.