Galaxy Alignments: Observations and Impact on Cosmology

By Donnacha Kirk, Michael L. Brown, H. Hoekstra, B. Joachimi, Thomas D. Kitching, Rachel Mandelbaum, C. Sifón, M. Cacciato, A. Choi, Alina A. Kiessling and 3 more. 2015

134 citations recorded by the source corpus.

Galaxy shapes are not randomly oriented, rather they are statistically aligned in a way that can depend on formation environment, history and galaxy type. Studying the alignment of galaxies can therefore deliver important information about the physics of galaxy formation and evolution as well as the growth of structure in the Universe. In this review paper we summarise key measurements of galaxy alignments, divided by galaxy type, scale and environment. We also cover the statistics and formalism necessary to understand the observations in the literature. With the emergence of weak gravitational lensing as a precision probe of cosmology, galaxy alignments have taken on an added importance because they can mimic cosmic shear, the effect of gravitational lensing by large-scale structure on observed galaxy shapes. This makes galaxy alignments, commonly referred to as intrinsic alignments, an important systematic effect in weak lensing studies. We quantify the impact of intrinsic alignments on cosmic shear surveys and finish by reviewing practical mitigation techniques which attempt to remove contamination by intrinsic alignments.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/7c43c04f43dad9cd4776f072b377b853f7ce8997

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Citations in the corpus

Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data (2018, background): “Intrinsic shape correlations due to tidal interactions also result in systematics in cosmic shear measurements (Hirata & Seljak 2004; Joachimi et al. 2015; Kirk et al. 2015).”
The first-year shear catalog of the Subaru Hyper Suprime-Cam Subaru Strategic Program Survey (2017, background): “…for the ensemble of galaxies, avoiding certain systematic errors in the process. alignments of galaxy shapes (Joachimi et al. 2015; Kiessling et al. 2015; Kirk et al. 2015; Troxel & Ishak 2015) and the impact of baryonic effects on the matter power spectrum (Zentner et al. 2013; Mead et al. 2015).”
Cosmological constraints from cosmic shear two-point correlation functions with HSC survey first-year data (2019, background): “4.2 Intrinsic alignment model The so-called intrinsic alignment (IA) of galaxy shapes is another major astrophysical systematic in the measurement of the cosmic shear TPCFs (see Kirk et al. 2015; Troxel & Ishak 2015, for recent reviews).”
Galaxy Alignments: An Overview (2015, background): “2015) as well as observational results and the impact on cosmology (Kirk et al. 2015).”