The PAU Survey: Intrinsic alignments and clustering of narrow-band photometric galaxies

Harry Johnston*, Benjamin Joachimi, Peder Norberg, Henk Hoekstra, Martin Eriksen, Maria Cristina Fortuna, Giorgio Manzoni, Santiago Serrano, Malgorzata Siudek, Luca Tortorelli, Jacobo Asorey, Laura Cabayol, Jorge Carretero, Ricard Casas, Francisco Castander, Martin Crocce, Enrique Fernandez, Juan García-Bellido, Enrique Gaztanaga, Hendrik HildebrandtRamon Miquel, David Navarro-Girones, Cristobal Padilla, Eusebio Sanchez, Ignacio Sevilla-Noarbe, Pau Tallada-Crespí

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We present the first measurements of the projected clustering and intrinsic alignments (IA) of galaxies observed by the Physics of the Accelerating Universe Survey (PAUS). With photometry in 40 narrow optical passbands (4500 Å-8500 Å), the quality of photometric redshift estimation is σz  ∼  0.01(1 + z) for galaxies in the 19 deg2 Canada-France-Hawaii Telescope Legacy Survey W3 field, allowing us to measure the projected 3D clustering and IA for flux-limited, faint galaxies (i  <  22.5) out to z  ∼  0.8. To measure two-point statistics, we developed, and tested with mock photometric redshift samples, 'cloned' random galaxy catalogues which can reproduce data selection functions in 3D and account for photometric redshift errors. In our fiducial colour-split analysis, we made robust null detections of IA for blue galaxies and tentative detections of radial alignments for red galaxies (∼1 - 3σ), over scales of 0.1 - 18  h-1 Mpc. The galaxy clustering correlation functions in the PAUS samples are comparable to their counterparts in a spectroscopic population from the Galaxy and Mass Assembly survey, modulo the impact of photometric redshift uncertainty which tends to flatten the blue galaxy correlation function, whilst steepening that of red galaxies. We investigate the sensitivity of our correlation function measurements to choices in the random catalogue creation and the galaxy pair-binning along the line of sight, in preparation for an optimised analysis over the full PAUS area.

Original languageEnglish
Article numberA147
Number of pages23
JournalAstronomy and Astrophysics
Publication statusPublished - 19 Feb 2021


  • Cosmology: Observations
  • Gravitational lensing: weak
  • Large-scale structure of Universe
  • UKRI
  • STFC
  • ST/P000541/1
  • ST/T000244/1
  • ST/P006744/1

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