Scope: Lectures 11-12 · Purpose: Compute linear growth for the course fiducial model and compare geometry and growth observables without combining incompatible published summaries.
Setup and data
- Use the stated flat matter-plus-Lambda background; the provided growth calculation neglects radiation and massive neutrinos.
- Growth values are model outputs, not observed f sigma8 measurements.
- Use DES S8 only to discuss a compressed late-time amplitude constraint.
Procedure
- Calculate normalized D(a) at z=0, 0.5, and 1 from the integral solution.
- Estimate f=d ln D/d ln a by centered finite differences and document step-size convergence.
- Explain how RSD's f sigma8 differs from a geometric BAO observable.
- Create a table that tags each quantity as measured, derived, or model-predicted.
- State two extensions that make growth scale-dependent or alter the GR prediction.
Deliverables
Deliver: script, growth table/plot, finite-difference convergence check, and an evidence-category table.
Assessment criteria
Rubric: growth method 30%; numerical convergence 20%; observable distinction 20%; physical interpretation 20%; reproducibility 10%.
Uncertainty and interpretation
Report numerical precision, input uncertainty, model assumptions, and covariance availability separately. Label every output as directly measured, published summary, derived, or model/synthetic. A successful script run is not evidence that the scientific interpretation is valid.
Revisions and resubmissions are encouraged. Credit is based on defensible reasoning, validation, provenance, and clear limitations.