CFHTLenS: weak lensing constraints on the ellipticity of galaxy-scale matter haloes and the galaxy-halo misalignment

Schrabback, T.; Hilbert, Stefan; Hoekstra, Henk; Simon, Patrick; Uitert, Edo van; Erben, T.; Heymans, Catherine; Hildebrandt, Hendrik; Kitching, Thomas D.; Mellier, Y.; Miller, L.; Waerbeke, Ludovic Van; Bett, Philip E.; Coupon, J.; Fu, Liping; Hudson, Michael J.; Joachimi, Benjamin; Kilbinger, M.; Kuijken, Konrad

doi:10.1093/mnras/stv2053

Cited by 28 publications

(50 citation statements)

References 153 publications

(234 reference statements)

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“…They found the strongest alignment for the brightest, red lenses, with a significance ∼ 2 − 3σ. Other work by van Uitert et al (2012) and Schrabback et al (2015) with the same estimator and other surveys found little alignment.…”

Section: Introductionmentioning

confidence: 68%

The ellipticity of galaxy cluster haloes from satellite galaxies and weak lensing

Shin

Clampitt

Jain

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We study the ellipticity of galaxy cluster halos as characterized by the distribution of cluster galaxies and as measured with weak lensing. We use monte-carlo simulations of elliptical cluster density profiles to estimate and correct for Poisson noise bias, edge bias and projection effects. We apply our methodology to 10,428 SDSS clusters identified by the redMaPPer algorithm with richness above 20. We find a mean ellipticity = 0.271 ± 0.002 (stat) ±0.031 (sys) corresponding to an axis ratio = 0.573 ± 0.002 (stat) ±0.039 (sys). We compare this ellipticity of the satellites to the halo shape, through a stacked lensing measurement using optimal estimators of the lensing quadrupole based on Clampitt and Jain (2016). We find a best-fit axis ratio of 0.56 ± 0.09 (stat) ±0.03 (sys), consistent with the ellipticity of the satellite distribution. Thus cluster galaxies trace the shape of the dark matter halo to within our estimated uncertainties. Finally, we restack the satellite and lensing ellipticity measurements along the major axis of the cluster central galaxy's light distribution. From the lensing measurements we infer a misalignment angle with an RMS of 30 • ± 10 • when stacking on the central galaxy. We discuss applications of halo shape measurements to test the effects of the baryonic gas and AGN feedback, as well as dark matter and gravity. The major improvements in signal-to-noise expected with the ongoing Dark Energy Survey and future surveys from LSST, Euclid and WFIRST will make halo shapes a useful probe of these effects.

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Section: Introductionmentioning

confidence: 68%

The ellipticity of galaxy cluster haloes from satellite galaxies and weak lensing

Shin

Clampitt

Jain

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Predictions for the alignments of the luminous shapes of galaxies can then be obtained by augmenting this information with models describing the galaxy content of the halos and how the shapes of the galaxy light relate to the host dark matter halo properties (Joachimi et al 2013a,b). This approach requires one to also specify the expected alignment of galaxies within their host halo, which is still quite uncertain (Mandelbaum et al 2006b;Bett 2012;Schrabback et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Intrinsic alignments of galaxies in the Illustris simulation

Hilbert

Schneider

et al. 2017

Monthly Notices of the Royal Astronomical Society

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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, redshift, and photometric type, and on the employed shape measurement method. The correlations considered include the matter density-intrinsic ellipticity (mI), galaxy density-intrinsic ellipticity (dI), gravitational shear-intrinsic ellipticity (GI), and intrinsic ellipticityintrinsic ellipticity (II) correlations. We find stronger correlations for more massive and more luminous galaxies, as well as for earlier photometric types, in agreement with observations. Moreover, the correlations significantly depend on the choice of shape estimator, even if calibrated to serve as unbiased shear estimators. In particular, shape estimators that down-weight the outer parts of galaxy images produce much weaker IA signals on intermediate and large scales than methods employing flat radial weights. The expected contribution of intrinsic alignments to the observed ellipticity correlation in tomographic cosmic shear surveys may be below one percent or several percent of the full signal depending on the details of the shape measurement method. A comparison of our results to a tidal alignment model indicates that such a model is able to reproduce the IA correlations well on intermediate and large scales, provided the effect of varying galaxy density is correctly taken into account. We also find that the GI contributions to the observed ellipticity correlations could be inferred directly from measurements of galaxy density-intrinsic ellipticity correlations, except on small scales, where systematic differences between mI and dI correlations are large.

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“…Observations such as gravitational lensing, or stellar and satellites kinematics, may place constraints on the shape of the haloes and the corresponding gravitational field (e.g., Bailin et al 2008;Howell & Brainerd 2010;Deason et al 2011;Bett 2012;Hayashi & Chiba 2012, 2015van Uitert et al 2012;Joachimi et al 2013aJoachimi et al , 2013bVera-Ciro & Helmi 2013;Schrabback et al 2015). These observations also place constraints on MOND as well.…”

Section: Start From a Model Of Gravitational Accelerationmentioning

confidence: 99%

On the Problem of Deformed Spherical Systems in Modified Newtonian Dynamics

2016

ApJ

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Based on Newtonian dynamics, observations show that the luminous masses of astrophysical objects that are the size of a galaxy or larger are not enough to generate the measured motions which they supposedly determine. This is typically attributed to the existence of dark matter, which possesses mass but does not radiate (or absorb radiation). Alternatively, the mismatch can be explained if the underlying dynamics is not Newtonian. Within this conceptual scheme, Modified Newtonian Dynamics (MOND) is a successful theoretical paradigm. MOND is usually expressed in terms of a nonlinear Poisson equation, which is difficult to analyze for arbitrary matter distributions. We study the MONDian gravitational field generated by slightly non-spherically symmetric mass distributions based on the fact that both Newtonian and MONDian fields are conservative (which we refer to as the compatibility condition). As the non-relativistic version of MOND has two different formulations (AQUAL and QuMOND) and the compatibility condition can be expressed in two ways, there are four approaches to the problem in total. The method involves solving a suitably defined linear deformation potential, which generally depends on the choice of MOND interpolation function. However, for some specific form of the deformation potential, the solution is independent of the interpolation function.

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CFHTLenS: weak lensing constraints on the ellipticity of galaxy-scale matter haloes and the galaxy-halo misalignment

Cited by 28 publications

References 153 publications

The ellipticity of galaxy cluster haloes from satellite galaxies and weak lensing

The ellipticity of galaxy cluster haloes from satellite galaxies and weak lensing

Intrinsic alignments of galaxies in the Illustris simulation

On the Problem of Deformed Spherical Systems in Modified Newtonian Dynamics

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