Field-level inference of galaxy intrinsic alignment from the SDSS-III BOSS survey. Issue 8 (1st August 2022)

• Record Type: Journal Article
• Authors: Tsaprazi, Eleni; Nguyen, Nhat-Minh; Jasche, Jens; Schmidt, Fabian; Lavaux, Guilhem
• Is Part Of: Journal of cosmology and astroparticle physics. Volume 2022:Issue 8(2022)
• Publication Date: 2022-08-01
• Subjects: cosmic web -- galaxy evolution -- galaxy formation -- weak gravitational lensing; Cosmology -- Periodicals; Astrophysics -- Periodicals; 523.0105
• DOI: 10.1088/1475-7516/2022/08/003
• Languages: English
• ISSNs: 1475-7516

Abstract

Abstract: As a large-scale overdensity collapses, it affects the orientation and shape of galaxies that form, by exerting tidal shear along their axes. Therefore, the shapes of elliptical galaxies align with the tidal field of cosmic structures. This intrinsic alignment provides insights into galaxy formation and the primordial universe, complements late-time cosmological probes and constitutes a significant systematic effect for weak gravitational lensing observations. In the present study, we provide constraints on the linear alignment model using a fully Bayesian field-level approach, using galaxy shape measurements from the SDSS-III BOSS LOWZ sample and three-dimensional tidal fields constrained with the LOWZ and CMASS galaxy samples of the SDSS-III BOSS survey. We find 4 σ evidence of intrinsic alignment, with an amplitude of AI = 2.9 ± 0.7 at 20 Mpch.