Data Overview
The analysis combines 1,590 Pantheon+SH0ES supernovae (after a redshift cut, out of 1,701) with 13 DESI DR2 BAO measurements, for N = 1,603 data points in the AIC/BIC. Raw survey files are not committed to the repository; the pipeline expects four files in data/raw/.
At a glance
| Pantheon+SH0ES | DESI DR2 BAO | |
|---|---|---|
| Observable | distance modulus μ(z) | DV/rd, DM/rd, DH/rd |
| Points used | 1,590 | 13 |
| Selection | z > 0.01 | none |
| Covariance | full STAT+SYS | full BAO matrix |
| Files | Pantheon+SH0ES.dat, Pantheon+SH0ES_STAT+SYS.cov | desi_gaussian_bao_ALL_GCcomb_mean.txt, …_cov.txt |
| Acquisition | manual download (external product) | python scripts/download_data.py |
Fixed sound horizon
BAO observables are divided by rd, which is fixed to 147.09 Mpc rather than fitted. The two probes therefore share one assumption about early-universe physics; see Known Limitations.
Where the data enter
Pantheon+SH0ES.dat ──► z, μ_obs, σ_μ (z > cut) ─┐
Pantheon+SH0ES_STAT+SYS.cov ──► C_SN (kept rows) ─┤
├─► χ²_SN + χ²_BAO ─► ln p ─► emcee
DESI mean file ──► (z, value, type) × N_BAO ─┤
DESI cov file ──► C_BAO ─┘
The two probes are combined by adding their χ² — they are treated as independent. Details: Covariance Handling and Likelihood Functions.
Related pages