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Coherent alignments of galaxy shapes, often called "intrinsic alignments" (IA), are the most significant source of astrophysical uncertainty in weak lensing measurements. We develop the tidal alignment model of IA and demonstrate its…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-19 Jonathan Blazek , Uroš Seljak , Rachel Mandelbaum

Galaxy intrinsic alignments (IA) are a critical uncertainty for current and future weak lensing measurements. We describe a perturbative expansion of IA, analogous to the treatment of galaxy biasing. From an astrophysical perspective, this…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-13 Jonathan Blazek , Niall MacCrann , M. A. Troxel , Xiao Fang

The intrinsic alignments (IA) of galaxies, regarded as a contaminant in weak lensing analyses, represents the correlation of galaxy shapes due to gravitational tidal interactions and galaxy formation processes. As such, understanding IA is…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-23 Sneh Pandya , Yuanyuan Yang , Nicholas Van Alfen , Jonathan Blazek , Robin Walters

We show that the spatial correlation of the intrinsic alignments (IAs) of galaxies, measured in galaxy redshift surveys, offers a precision route to improve the geometrical and dynamical constraints on cosmology. The IA has been treated as…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-25 Atsushi Taruya , Teppei Okumura

In the context of cosmological weak lensing studies, intrinsic alignments (IAs) are one the most complicated astrophysical systematic to model, given the poor understanding of the physical processes that cause them. A number of modelling…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-10 Anya Paopiamsap , Natalia Porqueres , David Alonso , Joachim Harnois-Deraps , C. Danielle Leonard

The intrinsic alignments (IA) of galaxies, a key contaminant in weak lensing analyses, arise from correlations in galaxy shapes driven by tidal interactions and galaxy formation processes. Accurate IA modeling is essential for robust…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-03 Sneh Pandya , Yuanyuan Yang , Nicholas Van Alfen , Jonathan Blazek , Robin Walters

The intrinsic alignment (IA) of galaxies is potentially a major limitation in deriving cosmological constraints from weak lensing surveys. In order to investigate this effect we assign intrinsic shapes and orientations to galaxies in the…

We study intrinsic alignments (IA) of galaxy image shapes within the Illustris cosmic structure formation simulations. We investigate how IA correlations depend on observable galaxy properties such as stellar mass, apparent magnitude,…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-12 Stefan Hilbert , Dandan Xu , Peter Schneider , Volker Springel , Mark Vogelsberger , Lars Hernquist

The alignments between galaxies, their underlying matter structures, and the cosmic web constitute vital ingredients for a comprehensive understanding of gravity, the nature of matter, and structure formation in the Universe. We provide an…

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 intrinsic alignment (IA) of galaxy shapes probes the underlying gravitational tidal field, thus offering cosmological information complementary to galaxy clustering. In this paper, we perform a Fisher forecast to assess the benefit of…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-06 Junsup Shim , Teppei Okumura , Atsushi Taruya

The shapes of galaxies are not randomly oriented on the sky. During the galaxy formation and evolution process, environment has a strong influence, as tidal gravitational fields in the large-scale structure tend to align nearby galaxies.…

We extend current models of the halo occupation distribution (HOD) to include a flexible, empirical framework for the forward modeling of the intrinsic alignment (IA) of galaxies. A primary goal of this work is to produce mock galaxy…

Intrinsic alignments (IA) of galaxies is one of the key secondary signals to cosmic shear measurements, and must be modeled to interpret weak lensing data and infer the correct cosmology. There are large uncertainties in the physical…

Investigating intrinsic alignments (IAs) of galaxy shapes is important not only to constrain cosmological parameters unbiasedly from gravitational lensing but also to extract cosmological information complimentary to galaxy clustering…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-26 Teppei Okumura , Atsushi Taruya

The intrinsic alignment (IA) of galaxies is a major astrophysical contaminant to weak gravitational lensing measurements, and the study of its dependence on galaxy properties helps provide meaningful physical priors that aid cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-16 Christos Georgiou , Nora Elisa Chisari , Maciej Bilicki , Francesco La Barbera , Nicola R. Napolitano , Nivya Roy , Crescenzo Tortora

Intrinsic alignments (IA), correlations between the intrinsic shapes and orientations of galaxies on the sky, are both a significant systematic in weak lensing and a probe of the effect of large-scale structure on galactic structure and…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-18 Denise M. Schmitz , Christopher M. Hirata , Jonathan Blazek , Elisabeth Krause

The intrinsic alignment (IA) of galaxies acts as a systematic effect in weak lensing measurements and tends to introduce biases. It mimics the gravitational lensing signal which makes it difficult to distinguish it from the true…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-08 Abinash Das

The galaxy intrinsic alignment (IA) is a major challenge of weak lensing cosmology. To alleviate this problem, Zhang (2010, MNRAS, 406, L95) proposed a self-calibration method, independent of IA modeling. This proposal relies on several…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-05 Xian-guang Meng , Yu Yu , Pengjie Zhang , Yipeng Jing

We present measurements of the intrinsic alignments (IAs) of the star-forming gas of galaxies in the EAGLE simulations. Radio continuum imaging of this gas enables cosmic shear measurements complementary to optical surveys. We measure the…

Astrophysics of Galaxies · Physics 2022-02-16 Alexander D. Hill , Robert A. Crain , Ian G. McCarthy , Shaun T. Brown
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