The dependence of intrinsic alignment of galaxies on wavelength using KiDS and GAMA

Georgiou, Christos; Johnston, Harry; Hoekstra, Henk; Viola, Massimo; Kuijken, Konrad; Joachimi, Benjamin; Chisari, Nora Elisa; Farrow, Daniel J.; Hildebrandt, Hendrik; Holwerda, Benne W.; Kannawadi, Arun

doi:10.1051/0004-6361/201834219

Cited by 26 publications

(47 citation statements)

References 79 publications

(90 reference statements)

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“…As tidal processes typically affect larger galactic radii, the IA signal may then depend on the choice of filter width. This was confirmed most convincingly by Georgiou et al (2019a), but also see Singh & Mandelbaum (2016).…”

Section: Galaxy Shape Estimationmentioning

confidence: 53%

“…GAMA achieved high completeness ( 98%) down to r < 19.8 over 180 deg 2 within the equatorial fields G9, G12, G15 (60 deg 2 apiece). We compare the correlation functions we measure in PAUS with analogous measurements made in GAMA and presented in Johnston et al (2019), where details of shape measurements (from Kilo Degree Survey imaging: de Jong et al 2013;Georgiou et al 2019a), sample characteristics, covariance estimation etc., can be found. The observed and absolute Notes.…”

Section: Gamamentioning

confidence: 99%

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The PAU Survey: Intrinsic alignments and clustering of narrow-band photometric galaxies

Johnston

Joachimi

Norberg

et al. 2021

A&A

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We present the first measurements of the projected clustering and intrinsic alignments (IA) of galaxies observed by the Physics of the Accelerating Universe Survey (PAUS). With photometry in 40 narrow optical passbands (4500 Å–8500 Å), the quality of photometric redshift estimation is σz ∼ 0.01(1 + z) for galaxies in the 19 deg2 Canada-France-Hawaii Telescope Legacy Survey W3 field, allowing us to measure the projected 3D clustering and IA for flux-limited, faint galaxies (i < 22.5) out to z ∼ 0.8. To measure two-point statistics, we developed, and tested with mock photometric redshift samples, ‘cloned’ random galaxy catalogues which can reproduce data selection functions in 3D and account for photometric redshift errors. In our fiducial colour-split analysis, we made robust null detections of IA for blue galaxies and tentative detections of radial alignments for red galaxies (∼1 − 3σ), over scales of 0.1 − 18 h−1 Mpc. The galaxy clustering correlation functions in the PAUS samples are comparable to their counterparts in a spectroscopic population from the Galaxy and Mass Assembly survey, modulo the impact of photometric redshift uncertainty which tends to flatten the blue galaxy correlation function, whilst steepening that of red galaxies. We investigate the sensitivity of our correlation function measurements to choices in the random catalogue creation and the galaxy pair-binning along the line of sight, in preparation for an optimised analysis over the full PAUS area.

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Section: Galaxy Shape Estimationmentioning

confidence: 53%

Section: Gamamentioning

confidence: 99%

The PAU Survey: Intrinsic alignments and clustering of narrow-band photometric galaxies

Johnston

Joachimi

Norberg

et al. 2021

A&A

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“…2, in which we plot the constraints on f h versus M 200c for the individual surveys and stellar mass bins. Our results can also be compared to a recent halo shape analysis of the fourth KiDS data release (Georgiou et al 2019b, see Fig. 2), which we discuss further in Sect.…”

Section: Resultsmentioning

confidence: 68%

Tightening weak lensing constraints on the ellipticity of galaxy-scale dark matter haloes

Schrabback

Hoekstra

Waerbeke

et al. 2021

A&A

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Cosmological simulations predict that galaxies are embedded into triaxial dark matter haloes, which appear approximately elliptical in projection. Weak gravitational lensing allows us to constrain these halo shapes and thereby test the nature of dark matter. Weak lensing has already provided robust detections of the signature of halo flattening at the mass scales of groups and clusters, whereas results for galaxies have been somewhat inconclusive. Here we combine data from five weak lensing surveys (NGVSLenS, KiDS/KV450, CFHTLenS, CS82, and RCSLenS, listed in order of most to least constraining) in order to tighten observational constraints on galaxy-scale halo ellipticity for photometrically selected lens samples. We constrain fh, the average ratio between the aligned component of the halo ellipticity and the ellipticity of the light distribution, finding fh = 0.303−0.079+0.080 for red lens galaxies and fh = 0.217−0.159+0.160 for blue lens galaxies when assuming elliptical Navarro-Frenk-White density profiles and a linear scaling between halo ellipticity and galaxy ellipticity. Our constraints for red galaxies constitute the currently most significant (3.8σ) systematics-corrected detection of the signature of halo flattening at the mass scale of galaxies. Our results are in good agreement with expectations from the Millennium Simulation that apply the same analysis scheme and incorporate models for galaxy–halo misalignment. Assuming these misalignment models and the analysis assumptions stated above are correct, our measurements imply an average dark matter halo ellipticity for the studied red galaxy samples of ⟨|ϵh|⟩ = 0.174 ± 0.046, where |ϵh| = (1 − q)/(1 + q) relates to the ratio q = b/a of the minor and major axes of the projected mass distribution. Similar measurements based on larger upcoming weak lensing data sets can help to calibrate models for intrinsic galaxy alignments, which constitute an important source of systematic uncertainty in cosmological weak lensing studies.

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“…The area A iso of the galaxy's isophote is computed using the ISOAREA_IMAGE by SExtractor (Bertin & Arnouts 1996). The shape measurement procedure is the same as described in Georgiou et al (2019b) and we point the interested reader to their Section 2 for a detailed description of the algorithm. In Appendix A we report our analysis of the measured shape bias for different setups, which led to our final choice reported above.…”

Section: Deimosmentioning

confidence: 99%

“…We also explore the dependence of our signal on the shape measurement algorithm used to create the shape catalogue. We compare the signal as measured by two complementary algorithms: DEIMOS (DEconvolution In MOment Space; Melchior et al 2011), which has been widely used in IA studies (Georgiou et al 2019b;Johnston et al 2019;Georgiou et al 2019a), and lensfit (Miller et al 2007(Miller et al , 2013 which has been used for the cosmological analysis of the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS; Heymans et al 2013) and the Kilo-Degree Survey (KiDS; see Asgari et al 2021, and references therein).…”

Section: Introductionmentioning

confidence: 99%

KiDS-1000: Constraints on the intrinsic alignment of luminous red galaxies

Fortuna,

Hoekstra,

Johnston

et al. 2021

Preprint

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We constrain the luminosity and redshift dependence of the intrinsic alignment (IA) of a nearly volume-limited sample of luminous red galaxies selected from the fourth public data release of the Kilo-Degree Survey (KiDS-1000). To measure the shapes of the galaxies, we used two complementary algorithms, finding consistent IA measurements for the overlapping galaxy sample. The global significance of IA detection across our two independent luminous red galaxy samples, with our favoured method of shape estimation, is ∼ 10.7σ. We find no significant dependence with redshift of the IA signal in the range 0.2 < z < 0.8, nor a dependence with luminosity below L r 2.9 × 10 10 h −2 L r, . Above this luminosity, however, we find that the IA signal increases as a power law, although our results are also compatible with linear growth within the current uncertainties. This behaviour motivates the use of a broken power law model when accounting for the luminosity dependence of IA contamination in cosmic shear studies.

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The dependence of intrinsic alignment of galaxies on wavelength using KiDS and GAMA

Cited by 26 publications

References 79 publications

The PAU Survey: Intrinsic alignments and clustering of narrow-band photometric galaxies

The PAU Survey: Intrinsic alignments and clustering of narrow-band photometric galaxies

Tightening weak lensing constraints on the ellipticity of galaxy-scale dark matter haloes

KiDS-1000: Constraints on the intrinsic alignment of luminous red galaxies

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