WP-B1.3: Galaxy clustering - Implementation Enzo Branchini (INAF - Brera , Italy)

1. WP-B1.3: Galaxy clustering - Implementation EnzoBranchini (INAF - Brera, Italy) Lado Samushia (University of Portsmouth, UK) • WP-B2.3: Galaxy clustering – Validation Carlton Baugh (Durham University, UK) MatteoViel (INAF – Trieste, Italy)

2. Galaxy Clustering – Implementation WP deliverables: Software prototype for computing • Correlation function. • Power-spectrum. • Three-point function. • Bispectrum. and cosmology-independent errors WP Status: • 25 members (mostly staff) - 5 nations. • Mailing list created, census of available expertise performed.

3. Challenges Standard algorithms for computing 2pt and 3pt statistics exits. They have been tested and used on previous surveys. Numerical challenges: • 50,000,000 galaxies in spectroscopic survey. • 1,500,000,000 galaxies in imaging survey. • Full sky

4. Challenges Methodology challenges: • Confusion/Purity • Angular dependence of systematics due to slitless spectroscopy • Density dependence of systematics due to slitless spectroscopy

5. Challenges • Euclid will make possible extremely high precision measurements of clustering statistics. • Level 0 requirements are σ(w0). • Need to make sure that observational/methodology induced statistical errors are under control so that Euclid data can achieve its statistical promise.

6. sub-workpackages (Software) Software prototype for ξ(σ,π), + covariance matrix. Software prototype for P(k,μ) + covariance matrix. Software prototype for η+ covariance matrix. Software prototype for B + covariance matrix.

7. sub-workpackages (methodology + systematics) Methodology Pair/Triplet counting algorithms Window functions Cosmology-independent errors Observational systematics angular systematics (star density, zodiacal light, ) radial systematics (redshift failure, confusion) Deep field/Calibration Instrumental systematics (degradation with time, etc.)

8. Link to other WPs Development/Quality control WP-A1 Management/Inventory WP-A2 Documentation/Definition WP-A3 Selection functions Galaxy clustering – Implementation WP-B1.3 Clusters WP-B1.4 Internal data WP-B1.1 Galaxy clustering – Validation WP-B2.3

9. Interface with other OUs OU-SIM Mock photometric/spectroscopic surveys OU-PHZ/MER Preliminary version of photometric survey + calibration OU-LE3/Galaxy clustering implementation Preliminary version of spectroscopic survey + calibration OU-SIR/SPE/MER

10. Interface with GCSWG • Coordinate basis for computing clustering statistics • gauge invariant coordinates z, θ • Generic module for z, θ-> x, y, z • Correlation between cosmology independent and cosmology dependent covariance matrices.

11. Galaxy Clustering - Validation Validation tasks: • Algorithms for computation redshift-space P(k1,k2) • Algorithms for computation of xi(r_p, pi) • Algorithms for computation of covariance matrices • Algorithms for computation of 3pt function. • Algorithms for likelihood calculation to include cosmology independent terms

12. Galaxy Clustering - Validation Inputs: • Validation criteria from Galaxy clustering SWG • Algorithms developed and tested by WP-B1.3 • Mock catalogues (with masking + selection functions) from OU-SIM plus Cosmological Simulations WG • Preliminary version of Euclid spectroscopic & photometric surveys