ps7 - Phys/Astro 228: Extragalactic Astronomy and Cosmology...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Phys/Astro 228: Extragalactic Astronomy and Cosmology November 3 2006 C.P. Ma Problem Set 7 Due in class Friday November 17 Reading: Chapter 7 of Dodelson 1. Structure Formation I: Radiation Era In class we derived the time evolution of density perturbation in non-relativistic matter m (above the Jeans length) in the matter-dominated era. Here we will find the behavior of m in the radiation- dominated era. Assume a flat, = 0 universe for simplicity. (a) Assume that the perturbation in radiation, r , is negligible. Show that the linearized evolution equation for m can be written as d 2 m dy 2 + 2 + 3 y 2 y (1 + y ) d m dy 3 2 y (1 + y ) m = 0 , (1) where y m / r = a/a eq and a eq is the equality time. (b) At late time ( y 1), compare your solutions for m with those derived in class. (c) Verify that m y + 2 / 3 is a solution to eq. (1) in general. Can m grow much in the radiation- dominated era?...
View Full Document

Page1 / 2

ps7 - Phys/Astro 228: Extragalactic Astronomy and Cosmology...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online