sys_mapping
Inference of multiplicative and additive systematics in galaxy density maps.
User guide
- Overview
- Galaxy clustering and the role of systematics
- Notation and conventions
- The observed galaxy overdensity
- Systematic template maps
- Contamination model
- Gaussian log-likelihood (Eq. 17)
- Skew-normal log-likelihood (Eq. 18)
- Template PCA rotation (Appendix A)
- Noise debiasing (Eq. 21)
- Two-point function correction (Eq. 15–16)
- Model selection (Eq. 19)
- Per-galaxy systematic weights
- Summary of the workflow
- Analysis execution pipeline
- Installation
- Quickstart
- Methods overview
- Step 1 — Generate systematic template maps
- Step 2 — Simulate the galaxy field and inject contamination
- Step 3 — Compute the observed overdensity
- Step 4 — PCA rotation of templates
- Step 5 — Run all decontamination methods
- Step 6 — MCMC diagnostics: extract MAP estimates
- Step 7 — Likelihood ratio test
- Step 8 — Two-point function correction
- Expected output summary
- Results on 100 mock realisations
Methods & references
- Methods Reference
- Template pre-selection (Stage 1)
- Core contamination model
- Gaussian and skew-normal likelihood
- MCMC inference
- Template PCA rotation
- Noise debiasing
- Two-point function correction
- Likelihood ratio test (model selection)
- Pseudo-\(C_\ell\) power spectrum
- Block bootstrap covariance
- Jack-knife covariance
- ElasticNet regression
- Iterative Systematics Decontamination (ISD)
- Null tests and SNR ranking
- Mock catalog generation
- HEALPix map utilities
- Two-point function measurement
- Method comparison table
- Bibliography
Validation & tests
Application to real data: Legacy Survey DR10
- Running the real-data pipeline
- Results: systematic weights
- Run configuration
- Sample overview
- Systematics are detected: Likelihood Ratio Test
- Fractional systematic uncertainty on \(w(\theta)\)
- Is LS10 BGS (\(r < 19.5\)) systematics-limited?
- Cross-sample comparison (NSIDE 64)
- Per-sample results — all 9 samples
- MAP parameters — 11-template analysis (NSIDE 64)
- Outcome
- ElasticNet+ISD-1+OLS Results — LS10 BGS (auto-generated 2026-06-11T20:46Z)
- LS10 systematic-correction recommendations
- BGS VLIM log M* ≥ 9.0, z < 0.08 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 9.5, z < 0.12 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 10.0, z < 0.18 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 10.25, z < 0.22 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 10.5, z < 0.26 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 10.75, z < 0.31 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 11.0, z < 0.35 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 11.25, z < 0.35 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
- BGS VLIM log M* ≥ 11.5, z < 0.35 — detailed systematic analysis
- Sample statistics
- Goodness-of-fit: \(\hat{\sigma}\) by method and resolution
- Likelihood Ratio Test (additive vs combined model)
- Template amplitude ranking — additive model (MCMC-add, NSIDE 64)
- Template amplitude ranking — multiplicative model (MCMC-comb, NSIDE 64)
- Per-galaxy weight statistics (NSIDE 64)
- Systematic weight maps
- Systematic weight distributions
- Angular clustering w(θ) before and after correction
- Cosmological analysis verdict
API reference
- sys_mapping.contamination
- sys_mapping.likelihood
- sys_mapping.maps
- sys_mapping.inference
- sys_mapping.correction
- sys_mapping.model_selection
- sys_mapping.bootstrap
- sys_mapping.utils
- sys_mapping.power_spectrum
- sys_mapping.regression
- sys_mapping.diagnostics
- sys_mapping.mocks
- sys_mapping.glass_mocks
- sys_mapping.simulation
Development