Calculating the density parameter (Cosmology)

Hangst · Nov 27, 2012

Homework Statement

Decide the density parameter from the following data:

z=0.04, m= 17.38 and σ=0.19

Homework Equations

Definition of the density parameter:

Where p0 is the current density and pc is the critical density.

The Attempt at a Solution

I feel like I don't have enough information to calculate it as I'm unable to calculate the current density of the universe. Any help is greatly appreciated! Thanks.

Hangst · Nov 27, 2012

Two pictures of an attempt at a solution (no units)>

Worked Mathematica-style calculation of the density parameter: solve z = v/c = 0.04 for v, giving v = 1.199996 x 10^12 m/s; isolate distance x = 1.615068641 x 10^10; volume V = 1.741299136 x 10^31; density rho = 9.981053595 x 10^-31; then Omega_0 = rho/rho_c.

and

Typeset equations for critical density rho_c = 3 H_0^2 / (8 pi G) and density parameter Omega_0 = 9.981053595 x 10^-31 / (3 x 74.3^2 / (8 x 3.14 x 6.67 x 10^-11)), with blue computed results rho_c = 3 H^2 and Omega_0 = 1.009771187 x 10^-43 on the right.

Hangst · Nov 27, 2012

Hello? (hello)
Is there anybody in here?

Calculating the density parameter (Cosmology)

Homework Statement

Homework Equations

The Attempt at a Solution

Discussion

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