Introduction
Below I give a syllabus for the unit, together with guidance as to where you can find the relevant material. More detailed advice on how to approach the work is given in the introduction to Unit 1 , and will not be repeated here. You should aim to spend about 12 hours on the unit, plus a further 4 hours for the assessed exercise.
Syllabus and source
This unit is about the matter which makes up the Universe. Dynamical evidence strongly indicates that the Universe is dominated by dark matter, which may take several different forms. Baryonic matter may only constitute about 10% of the total, but it is the part in which most of the action takes place. We examine our current knowledge of how much baryonic and dark matter is present in the Universe, and the forms it may take. Note that your understanding of some of the observational results (e.g. constraints from high redshift SNIa) will be improved by Unit 5.
A lot of the material you are encountering here is close to the cutting edge of observational
cosmology. This means that it can change rapidly, and much of it is still under active debate. You will therefore find
disagreements between different authors. This can be a little confusing, but it represents the way science works. You
should flag up such areas of dispute in your notes when you spot them. Remember that things written even a few years ago
can be out of date; Bothun's book
contains a lot of useful material, but gives much more than you need on some of his pet topics.
| Topic | Sources | Comments |
| Types of matter: baryons, photons, neutrinos, dark matter | L1(2.5), L2(2.5), L3(2.5) | |
| Evidence for dark matter | ||
| - Introduction and M/L | B(4.1, 4.3.3-4.3.4), Van den Bergh paper | |
| - Dark matter near the sun |
B(4.2.2) |
Don't worry about
the detail here. |
| - Dark matter in galaxies | L1(8.1.3), RR(6.4), L2(9.1.3), L3(9.1.3), B(4.2.3, 4.3.1) |
|
| - Dark matter in clusters | RR(6.4), L2(9.1.4), L3(9.1.4), B(4.3.5) |
Only bother with the first part of the section in
Bothun, and note that his equation 4.20 is 1000 times too large! Revise
the
V.T. if necessary. |
| Forms of dark matter | ||
| (a) Baryonic dark matter - searches for baryonic dark matter - limits on baryonic dark matter |
L(8.2), RR(6.6), L2(9.2), L3(9.2), B(4.6.1) |
|
| (b) Non-baryonic dark matter - Hot and cold dark matter - Detection of non-baryonic dark matter |
L(8.2, 8.3), Berk, RR(6.8), L2(9.2,9.3), L3(9.2,9.3), B(4.6.4, 5.2.1) | Look here for some
amusement on this subject (sorry about the image quality). |
| Observed baryonic matter | ||
| - stars - intergalactic gas - Ly alpha forest clouds - baryon census and "missing baryons" |
Fukugita paper, RR(6.5-6.7) | Aim to understand where (& in what form) most of
the observed baryons are. Some of the numbers in the Fukugita paper are
now out of date, but the basic argument is still good. |
| Omega and dark energy |
||
| - CMB fluctuations and the value of Omega - High z SNIa and the case for accelerating expansion |
L2(A5.4, A2.3), L3(A5.4, A2.3), RR(5.5 and p.134-5), SCP, Unit 4 lecture |
You should understand this better after Unit 5. Concentrate on the results themselves for the present. Liddle is good on the CMB. |
| Best-buy (concordance) cosmology |
Krauss paper , Lahav & Liddle, Unit4 lecture |
Krauss is a fine example of the cautious
approach one should take to cosmological data, but is getting "old".
Lahav &
Liddle is up to date, but more advanced. |
Notes
- Key: RR=Rowan-Robinson, L1=Liddle 1st edition, L2=Liddle 2nd edition, L3= Liddle 3rd Edition, B=Bothun, Berk=Berkeley d.m. pages, SCP=Supernova Cosmology project website - relevant sections are given in brackets.
- The topics listed are not of equal size.
- References given are not by any means the only ones (e.g. check out some of the suggested reading material and other references) but they should provide a reasonable treatment.
- For the more complex topics (such as the distance scale) it pays to consult several sources and to synthesise the results. This takes longer, but should result in a better understanding.
Unit 4: Dark matter & baryons
Introduction
Syllabus and sources
Self-test problems
Units
- The Hot Big Bang
- Cosmological theory
- Evolution from the Big Bang
- Dark matter & baryons
- Observational properties and cosmological tests
Contact
Email:
Office: Physics West, 223