Intrinsic and extrinsic galaxy alignment

By P. Catelan, M. Kamionkowski, R. Blandford. 2000

333 citations recorded by the source corpus.

We show with analytic models that the assumption of uncorrelated intrinsic ellipticities of target sources that is usually made in searches for weak gravitational lensing arising from large-scale mass inhomogeneities (‘field lensing’) is unwarranted. If the orientation of the galaxy image is determined either by the angular momentum or by the shape of the halo in which it forms, then the image should be aligned preferentially with the component of the tidal gravitational field perpendicular to the line of sight. Long-range correlations in the tidal field will thus lead to long-range ellipticity–ellipticity correlations that mimic the shear correlations arising from weak gravitational lensing. We calculate the ellipticity–ellipticity correlation expected if halo shapes determine the observed galaxy shape, and we discuss uncertainties (which are still considerable) in the predicted amplitude of this correlation. The ellipticity–ellipticity correlation induced by angular momenta should be smaller. We consider several methods for discriminating between the weak-lensing (extrinsic) and intrinsic correlations, including the use of redshift information. An ellipticity–tidal-field correlation also implies the existence of an alignment of images of galaxies near clusters. Although the intrinsic alignment may complicate the interpretation of field-lensing results, it is inherently interesting as it may shed light on galaxy formation as well as on structure formation.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/471d01573ec4093ea010cf0756a07af1db87e008

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

The origin and implications of dark matter anisotropic cosmic infall on ~L * haloes (2004, methodology): “As recommended by Catelan et al. (2001), our measurement may also be used as a ‘numerical’ calibration of the relation between ellipticity and tidal fields.”
Spin-induced Galaxy Alignments and Their Implications for Weak-Lensing Measurements (2000, background): “The ellipticity correlation is therefore quartic in the angular momenta : This result shouldSvv@T P SLŒ LŒ LŒ @LŒ @T. be contrasted with the Ansatz of Catelan et al. (2001), which assumes the correlation to be quadratic in the angular momenta.8 The correlation strength Svv@T also depends on the mean”
Gravitational lensing (2010, background): “In shallow surveys, however, intrinsic source alignments may substantially contaminate any weak-shear signal [70, 92, 93, 176].”
Origins of weak lensing systematics, and requirements on future instrumentation (or knowledge of instrumentation) (2012, neutral): “…= (Pγ)−1〈εint〉+ (Pγ)−1Pγ 〈γ〉 (8) and we recover 〈γ̂〉 = 〈γ〉 so long as the intrinsic galaxy ellipticities are random and hence 〈εint〉 = 0 (but see Crittenden et al. 2001; Catelan et al. 2001; Natarajan et al. 2001; Joachimi & Schneider 2008; Schneider & Bridle 2010; Kirk et al. 2012, for…”
Cosmic Discordance: Are Planck CMB and CFHTLenS weak lensing measurements out of tune? (2014, methodology): “The NLA model is based on the linear alignment model (Catelan et al. 2001; Hirata & Seljak 2004), which assumes that galaxies are aligned with their haloes which are in turn are aligned with the local tidal gravitational field; for a given redshift the intrinsic galaxy ellipticity is taken to be…”
CFHTLenS tomographic weak lensing cosmological parameter constraints: Mitigating the impact of intrinsic galaxy alignments (2013, methodology): “In this analysis we have assumed a simple one-parameter model that scales the amplitude of the II and GI intrinsic alignment contamination expected from a linear tidal field alignment model of galaxy shape correlation (Catelan et al. 2001; Hirata & Seljak 2004; Bridle & King 2007).”
Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements (2007, methodology): “For this paper we simplify the linear alignment model presented in Catelan et al. (2001) and developed in Hirata et al. (2004) to use only the first term of Hirata et al. (2004) Equation 16, written P linγ̃I (k) = C21 ρ̄ 2 D̄2 P linδ (k) (6) where C1 is a normalization constant, and P lin δ (k) is…”
Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data (2018, background): “One is the correlation between the intrinsic shapes of two galaxies residing in the same local field (Heavens et al. 2000; Croft & Metzler 2000; Lee & Pen 2000; Catelan et al. 2001).”
Observational probes of cosmic acceleration (2012, background): “…for luminous red galaxies (Hirata et al., 2007; Mandelbaum et al., 2011), and that the linear alignment model, once considered a crude analytical tool (Catelan et al., 2001), is in fact an excellent description of the observations of early-type galaxies at ≥ 10h−1 Mpc scales (Blazek et al., 2011).”
The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts (2009, methodology): “In order to give fits with physical motivation, we fit the unknown amplitude in a linear alignment model (Catelan et al. 2001; Hirata & Seljak 2004).”
Galaxy Alignments: An Overview (2015, methodology): “Using a similar argument, but applying it directly in projection onto the sky, Catelan et al. (2001) proposed the following model for the intrinsic shear, γI,”
The Intrinsic Alignment of Galaxies and its Impact on Weak Gravitational Lensing in an Era of Precision Cosmology (2014, methodology): “, Catelan et al. (2001)) or by the mutual acquisition of angular momentum through tidal torquing (Sciama, 1955; Peebles, 1969; Doroshkevich, 1970; White, 1984) of aspherical protogalactic mass distributions during galaxy formation. This galaxy ellipticity or angular momentum alignment and the potent”
Core Cosmology Library: Precision Cosmological Predictions for LSST (2018, positive): “CCL supports the so-called “non-linear alignment model” (NLA), in which the intrinsic galaxy inertia tensor is proportional the local tidal tensor (Catelan et al. 2001; Hirata & Seljak 2004; Hirata et al. 2007): ∆IA` (k) = √ (`+ 2)!”