Halo shapes constrained from a pure sample of central galaxies in KiDS-1000

Abstract

We present measurements of $f_h$, the ratio of the aligned components of the projected halo and galaxy ellipticities, for a sample of central galaxies using weak gravitational lensing data from the Kilo-Degree Survey (KiDS). Using a lens galaxy shape estimation that is more sensitive to outer galaxy regions, we find $f_{\mathrm{h}}=0.50\pm 0.20$ for our full sample and $f_{\mathrm{h}}=0.55\pm 0.19$ for an intrinsically red (and therefore higher stellar-mass) sub-sample, rejecting the hypothesis of round halos and/or galaxies being un-aligned with their parent halo at $2.5\sigma$ and $2.9\sigma$, respectively. We quantify the 93.4% purity of our central galaxy sample using numerical simulations and overlapping spectroscopy from the Galaxy and Mass Assembly survey. This purity ensures that the interpretation of our measurements is not complicated by the presence of a significant fraction of satellite galaxies. Restricting our central galaxy ellipticity measurement to the inner isophotes, we find $f_{\mathrm{h}}=0.34\pm 0.17$ for our red sub-sample, suggesting that the outer galaxy regions are more aligned with their dark matter halos compared to the inner regions. Our results are in agreement with previous studies and suggest that lower mass halos are rounder and/or less aligned with their host galaxy than samples of more massive galaxies, studied in galaxy groups and clusters.

Accepted for publication in A&A

References in corpus (17)

• Galaxies in the Hubble Ultra Deep Field: I. Detection, Multiband Photometry, Photometric Redshifts, and Morphology
• The fourth data release of the Kilo-Degree Survey: ugri imaging and nine-band optical-IR photometry over 1000 square degrees
• Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -I. Methodology and a Fast Fitting Algorithm
• Intrinsic alignments of SDSS-III BOSS LOWZ sample galaxies
• An algorithm to build mock galaxy catalogues using MICE simulations
• KiDS-1000 catalogue: Weak gravitational lensing shear measurements
• The Masses and Shapes of Dark Matter Halos from Galaxy-Galaxy Lensing in the CFHTLS
• Galaxy Shapes and Intrinsic Alignments in The MassiveBlack-II Simulation
• A New Look at Massive Clusters: weak lensing constraints on the triaxial dark matter halos of Abell 1689, Abell 1835, & Abell 2204
• Alignment between galaxies and large-scale structure
• Angular distribution of satellite galaxies from the Sloan Digital Sky Survey Data Release 4
• Measuring the growth of matter fluctuations with third-order galaxy correlations
• The Anisotropic Distribution of Satellite Galaxies
• Luminous Satellites of Early-Type Galaxies I: Spatial Distribution
• The Flattened Dark Matter Halo of M31 as Deduced from the Observed HI Scale Heights
• Warm Dark Haloes Accretion Histories and their Gravitational Signatures
• Tightening weak lensing constraints on the ellipticity of galaxy-scale dark matter haloes

Cited by in corpus (7)

• KiDS-1000: Weak lensing and intrinsic alignment around luminous red galaxies
• Anisotropic Satellite Galaxy Quenching: A Unique Signature of Energetic Feedback by Supermassive Black Holes?
• The dark matter halo masses of elliptical galaxies as a function of observationally robust quantities
• Enhancing Photometric Redshift Catalogs Through Color-Space Analysis: Application to KiDS-Bright Galaxies
• The shape of dark matter haloes: results from weak lensing in the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS)
• Informed total-error-minimizing priors: Interpretable cosmological parameter constraints despite complex nuisance effects
• Ellipticities of Galaxy Cluster Halos from Halo-Shear-Shear Correlations