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The diagram shows the CMB power spectrum using data from WMAP, CBI and ACBAR. Briefly explain exactly what the "CMB power spectrum" actually is and what the symbols l and Cl represent. |
[3] |
| Essentially, this is asking you how we get from a map of the CMB sky to the plot shown in the diagram. This is bookwork. Ideally, you should be able to quote the various equations used in the notes, but if you can't a clear verbal description should do, since this question does not include the word "quantitatively"! |
| Compare and contrast, carefully but without detailed mathematics, the growth of structure in a universe dominated by (i) non-baryonic cold dark matter, (ii) non-baryonic hot dark matter and (iii) baryonic matter. | [5] |
| For each of the three scenarios, you need to think about two main issues: (1) when do structures start to grow, and (2) what size of structures can grow? Bear in mind that this is a compare and contrast question: separate descriptions of the three cases wil not get full marks; you need to focus on similarities and differences. |
(2005 Resit, part of Q8.)