On the origin of intrinsic alignment in cosmic shear measurements: an analytic argument

Abstract

Galaxy intrinsic alignment can be a severe source of error in weak-lensing studies. The problem has been widely studied by numerical simulations and with heuristic models, but without a clear theoretical justification of its origin and amplitude. In particular, it is still unclear whether intrinsic alignment of galaxies is dominated by formation and accretion processes or by the effects of the instantaneous tidal field acting upon them. We investigate this question by developing a simple model of intrinsic alignment for elliptical galaxies, based on the instantaneous tidal field. Making use of the galaxy stellar distribution function, we estimate the intrinsic alignment signal and find that although it has the expected dependence on the tidal field, it is too weak to account for the observed signal. This is an indirect validation of the standard view that intrinsic alignment is caused by formation and/or accretion processes.

11 pages, 4 figures, accepted for publication on Astronomy & Astrophysics

References in corpus (8)

• Intrinsic galaxy alignments from the 2SLAQ and SDSS surveys: luminosity and redshift scalings and implications for weak lensing surveys
• Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample
• Potential sources of contamination to weak lensing measurements: constraints from N-body simulations
• Galaxy Shapes and Intrinsic Alignments in The MassiveBlack-II Simulation
• The universal nature of subhalo accretion
• Separating intrinsic alignment and galaxy-galaxy lensing
• The construction of non-spherical models of quasi-relaxed stellar systems
• Detection of the velocity shear effect on the spatial distributions of the galactic satellites in isolated systems

Cited by in corpus (5)

• Alignment of galaxies relative to their local environment in SDSS-DR8
• The mass dependence of dark matter halo alignments with large-scale structure
• Direct signatures of the formation time of galaxies
• A rising tide: Intrinsic alignments since the turn of the millennium
• Probabilistic Estimators of Lagrangian Shape Biases: Universal Relations and Physical Insights