Figures from the lecture on Theoretical Astroparticle Physics

Big Bang Nucleosynthesis

1) Abundances in full equilibrium: Fig. 1 .
2) Observed vs. predicted abundances (from Fields and Sarkar, arXiv:astro-ph/0601514): Fig. 2 . The shaded boxes show the observationally allowed ranges of eta if only statistical errors are included, while the open boxes also include systematic uncertainties. The widths of the colored bands indicate the theoretical uncertainty of the calculation.
3) Updated results 2012 (from the 2012 Particle Data Group) Fig. 3 . Now the open boxes only include statistical errors, the (more relevant) colored boxes include the (often dominant) systematic uncertainties. The two shaded bands show the ``concordance'' value of eta from BBN alone (hatched) and from the CMB (cross-hatched); the latter determination is clearly more precise.
4) Updated results 2018 (from the 2018 Particle Data Group) Fig.4 . Now only the colored boxes are shown, which include the (often dominant) systematic uncertainties. The two shaded bands show the ``concordance'' value of eta from BBN alone (pink) and from the CMB (blue); the latter determination is clearly more precise. The main change from the 2012 version is the significantly reduced error of the D/H determination.
5) Updated PDG results 2024 Fig.5 . The changes from the 2018 version are quite small, the field has reached some maturity. Nevertheless occasionally controversies pop up about some measurements of primordial isotope abundances.
6) Constraints on abundance and lifetime of a decaying massive particle X, for different values of the dekadic log of its hadronic branching ratio; from Jedamzik, hep-ph/0604251: Fig. 6 . The (magenta) solid lines are based on a more conservative, hence reliable, interpretation of the observations, while the (blue) dashed lines are based on a more aggressive interpretation. Please do not confuse B_h=0 (i.e. no hadronic decay) with log₁₀B_h=0, i.e. purely hadronic decays of X.

Decoupling of WIMPs
Numerical solution of the Boltzmann equation for constant sigma v: Fig. 1. Note that the true chi density very quickly (within delta x of about 0.01) catches up to the equilibrium density, independent of the boundary condition assumed at inverse temperature x just 4 units below x_f. For x much larger than x_f the solution indeed becomes constant.

Evidence for Dark Matter

The Bullet Cluster : Fig. 1 (from the NASA web site).
This picture shows three different views of the collision between two galaxy clusters. The optical photo shows two collections of galaxies. However, most of the baryons in a cluster are in the hot, X-ray emitting gas. The red shades show the X-ray intensity. Clearly the gas of the cluster coming from the left has formed a bow shock, with a hot tip. The gas has been slowed down relative to the galaxies. The blue shades show the mass distribution, as derived from the lensing of background galaxies (by people from our own AIfA!). The mass followed the galaxies. This shows that most of the mass is in form of Dark Matter, which interacts with each other much more weakly than the hot gas does (similarly weakly as the galaxies, which basically just pass past each other).
CMB Isotropies : Fig. 2 (from Planck 2018).
The figure shows the CMB temperature anisotropies (technically the temperature-temperature [TT] correlation) as function of the order l of the spherical harmonics in which the anisotropy is expanded; the angular distance between two patches whose temperature is being compared scales like 1/l. Note that the measurement for each l is (almost) statistically independent (a small correlation is created by masking, i.e. removing part of the celestial sphere where foregrounds are too strong). The curve is a six parameter fit in Lambda-CDM (i.e. a model with a cosmological constant and cold dark matter), which clearly works very well.