The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: mock galaxy catalogues for the low-redshift sample

TL;DR

This work delivers 1000 mock galaxy catalogues for the BOSS LOWZ DR10/DR11 sample using the PTHalos method with a redshift-dependent Halo Occupation Distribution to match the evolving galaxy density. By generating 2LPT-based dark matter fields, identifying halos with FoF, reassigning halo masses to Tin08, and populating halos with galaxies via a five-parameter HOD that varies with n̄, the authors reproduce the observed clustering and redshift distribution, while applying DR10/DR11 geometry and completeness masks. They fit the HOD to both the power spectrum and the smoothed n(z) distribution using a joint χ^2 approach, obtaining best-fit parameters and validating the mocks against DR10/DR11 data; covariance matrices are computed from the mock ensemble and the mocks are publicly released. These mocks enable robust BAO analyses and systematic error assessments for current and future large-scale structure surveys by providing accurate covariance estimates and realistic survey geometries.

Abstract

We present one thousand mock galaxy catalogues for the analysis of the Low Redshift Sample (LOWZ, effective redshift z ~ 10.32) of the Baryon Oscillation Spectroscopic Survey Data Releases 10 and 11. These mocks have been created following the PTHalos method of Manera13 et al. (2013) revised to include new developments. The main improvement is the introduction of a redshift dependence in the Halo Occupation Distribution in order to account for the change of the galaxy number density with redshift. These mock catalogues are used in the analyses of the LOWZ galaxy clustering by the BOSS collaboration.

Figures (6)

• Figure 1: DR10 (left) and DR11 (right) survey footprints in equatorial coordinates. Northern Galactic Caps on the top and Southern Galactic caps on the bottom. The color code shows the completeness of each sector.
• Figure 2: Footprints of the LOWZ DR10 NGC and SGC mock galaxy catalogues. Two of each can fit without overlap in the celestial sphere. The same is true for the DR11 footprints.
• Figure 3: Top: Average of the absolute magnitude of the LOWZ DR10 (solid line) and DR11 (dashed line) galaxy samples. Bottom: Number density of galaxies of the LOWZ DR10 (solid line) and DR11 (dashed line) galaxy samples. In both panels the blue lines show the NGC sample and the green lines the SGC.
• Figure 4: HOD parameters $M_{cut}$ and $M_{1}$ as a function of the number density of galaxies. The points are from the list of table A1 in Parejko13. Blue: SDSS LRG (2PCF), Zheng09; Mandelbaum06; Cyan: SDSS LRG (Photo-z, BCL), Blake08; Pink: SDSS LRG (Photo-z, PW), Padmanabhan09; Dark Blue: Combo-17 Phleps06; Purple: SDSS LRG (Lensing), Mandelbaum06; Red: SDSS LRG (3PCF),Kulkarni07; Orange: NDWFS, Brown08; Green: 2SLAQ Wake08; Kulkarni07; Yellow: BOSS CMASS, White11; Magenta: LOWZ Parejko13
• Figure 5: Number density of galaxies of the LOWZ DR10 galaxy sample for the NGC (blue dots, lower values) and the SGC (green dots, higher values). Error bars show the rms of the 1000 mock galaxy catalogues. The solid lines are fits to the data. The mock galaxy catalogues n(z) are shown in dashed lines; all the redshift dependence of the mocks n(z) comes through the variation of the HOD.