Intrinsic correlation of galaxy shapes: implications for weak lensing measurements

By Alan Heavens, Alexandre Refregier, Catherine Heymans. 2000

253 citations recorded by the source corpus.

Weak gravitational lensing is now established as a powerful method to measure mass fluctuations in the universe. It relies on the measurement of small coherent distortions of the images of background galaxies. Even low-level correlations in the intrinsic shapes of galaxies could however produce a significant spurious lensing signal. These correlations are also interesting in their own right, since their detection would constrain models of galaxy formation. Using 3 × 10 4 10 5 halos found in N-body simulations, we compute the correlation functions of the intrinsic ellipticity of spiral galaxies assuming that the disk is perpendicular to the angular momentum of the dark matter halo. We also consider a simple model for elliptical galaxies, in which the shape of the dark matter halo is assumed to be the same as that of the light. For deep lensing surveys with median redshifts � 1, we find that intrinsic correlations of � 10 −4 on angular scales � � 0.1 10 ′ are generally below the expected lensing signal, and contribute only a small fraction of the excess signals reported on these scales. On larger scales we find limits to the intrinsic correlation function at a level � 10 −5 , which gives a (model-dependent) range of separations for which the intrinsic signal is about an order of magnitude below the ellipticity correlation function expected from weak lensing. Intrinsic correlations are thus negligible on these scales for dedicated weak lensing surveys. For wider but shallower surveys such as SuperCOSMOS, APM and SDSS, we cannot exclude the possibility that intrinsic correlations could dominate the lensing signal. We discuss how such surveys could be used to calibrate the importance of this effect, as well as study spin-spin correlations of spiral galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c635360fe9e12d108264c5926f3a0c4d13c1a249

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Citations in the corpus

The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts (2009, methodology): “While several analytical models for these alignments have also been developed (Croft & Metzler 2000; Heavens et al. 2000; Catelan et al. 2001; Crittenden et al. 2001; Jing 2002), they predict wildly varying levels of alignment, so observational constraints are necessary.”
Galaxy Alignments: Observations and Impact on Cosmology (2015, methodology): “The importance of the GI correlation was not fully appreciated in the earliest literature discussing mitigation (Croft & Metzler 2000; Heavens et al. 2000; Catelan et al. 2001).”
CFHTLenS tomographic weak lensing cosmological parameter constraints: Mitigating the impact of intrinsic galaxy alignments (2013, background): “The broad agreement in results between the first estimates from numerical simulations (Heavens et al. 2000; Croft & Metzler 2000), analytical studies (Catelan et al. 2001; Crittenden et al. 2001; Lee & Pen 2001), and the first low redshift observational constraints (Pen et al. 2000; Brown et al.…”
Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements (2007, methodology): “The HRH* model for the intrinsic alignment correlation function was proposed by Heavens et al. (2000b) and improved by Heymans et al. (2004b).”
Detection of large-scale intrinsic ellipticity—density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveys (2005, background): “HRH* model: This model is designed to make our results comparable to those of Heymans et al. (2004), who presented this modified version of the HRHmodel originated by Heavens et al. (2000).”
Potential sources of contamination to weak lensing measurements: constraints from N-body simulations (2006, background): “…(Catelan et al. 2001; Crittenden et al. 2001; Lee & Pen 2001; Porciani et al. 2002; Mackey et al. 2002) and through numerical simulations (Heavens et al. (2000), hereafter HRH, Croft & Metzler (2000); Jing (2002), H04), it is currently thought that this intrinsic alignment effect is…”
The Intrinsic Alignment of Galaxies and its Impact on Weak Gravitational Lensing in an Era of Precision Cosmology (2014, methodology): “smological parameters. These systematic eﬀects must be accounted for in order to make full use of the potential of ongoing and planned weak lensing surveys (see for example, Croft and Metzler (2000); Heavens et al. (2000); Bacon et al. (2001); Catelan et al. (2001); Erben et al. (2001); Bernstein an”