Dark matter halo concentrations in the Wilkinson Microwave Anisotropy Probe year 5 cosmology

We use the first 100 deg 2 of overlap between the Kilo-Degree Survey (KiDS) and the Galaxy And Mass Assembly (GAMA) survey to determine the galaxy halo mass of ∼10,000 spectroscopically-confirmed satellite galaxies in massive (M > 10 13 h −1 M ) galaxy groups. Separating the sample as a function of projected distance to the group centre, we jointly model the satellites and their host groups with Navarro-Frenk-White (NFW) density profiles, fully accounting for the data covariance. The probed satellite galaxies in these groups have total masses log M sub /(h −1 M ) ≈ 11.7 − 12.2 consistent across group-centric distance within the errorbars. Given their typical stellar masses, log M ,sat /(h −2 M ) ∼ 10.5, such total masses imply stellar mass fractions of M ,sat /M sub ≈ 0.04 h −1 . The average subhalo hosting these satellite galaxies has a mass M sub ∼ 0.015M host independent of host halo mass, in broad agreement with the expectations of structure formation in a ΛCDM universe.

“…We find that the normalization of the c(M, z) relation is significantly lower than the fiducial Duffy et al (2008) …”

Section: Group Masses and Mass-concentration Relationmentioning

confidence: 85%

Section: Satellite Contributionmentioning

confidence: 99%

Section: Fitting Proceduresmentioning

confidence: 99%

See 1 more Smart Citation

The masses of satellites in GAMA galaxy groups from 100 square degrees of KiDS weak lensing data

Sifón¹,

Cacciato²,

Hoekstra³

et al. 2015

“…Numerous dark-matter-only simulations have shown that the concentration of halos is expected to vary with both redshift and mass on average, and to have an intrinsic scatter of ∼ 20 per cent driven primarily by differences in accretion history (Navarro et al 1997;Bullock et al 2001;Zhao et al 2003Zhao et al , 2009Tasitsiomi et al 2004;Neto et al 2007;Gao et al 2008;Duffy et al 2008;Klypin et al 2011Klypin et al , 2016Ludlow et al 2012Ludlow et al , 2014Prada et al 2012;Dutton & Macciò 2014). Early work suggested a scaling relation similar to c ∝ (1 + z) −1 M −0.13 (Bullock et al 2001).…”

Section: Nfw Concentration-mass Relationmentioning

confidence: 99%

Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

Mantz

Allen

Morris

2016

This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the Cold Dark Matter (CDM) paradigm. We present constraints on the concentration-mass relation for massive clusters, finding a power-law mass dependence with a slope of κ m = −0.16 ± 0.07, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κ ζ = −0.17 ± 0.26), with an intrinsic scatter of σ ln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ∼ 50 kpc-1 Mpc), and test for departures from the simple Navarro, Frenk & White (NFW) form, for which the logarithmic slope of the density profile tends to −1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σ β = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σ α = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

“…In order to explore the parameter space, we will consider models with log Mvir = (14.0, 14.5, 15.0), (z d = 0.3, 0.9, 1.4), and q = (0.75, 0.85, 0.95) and their different combinations. For each (log Mvir, z) combination, we set the concentration cvir using the cvir -Mvir relation of Duffy et al (2008) neglecting its scatter. Note that weak lensing data are presently available for clusters mainly in the mass range (1, 40) × 10 14 M⊙ and redshift 0.2 z 1.4 (Sereno 2015; Groener et al 2015) so that our choice is representative of actual samples.…”

Section: Fiducial Modelmentioning

confidence: 99%

Improving lensing cluster mass estimate with flexion

Cardone

Vicinanza

et al. 2016

Gravitational lensing has long been considered as a valuable tool to determine the total mass of galaxy clusters. The shear profile as inferred from the statistics of ellipticity of background galaxies allows to probe the cluster intermediate and outer regions thus determining the virial mass estimate. However, the mass sheet degeneracy and the need for a large number of background galaxies motivate the search for alternative tracers which can break the degeneracy among model parameters and hence improve the accuracy of the mass estimate. Lensing flexion, i.e. the third derivative of the lensing potential, has been suggested as a good answer to the above quest since it probes the details of the mass profile. We investigate here whether this is indeed the case considering jointly using weak lensing, magnification and flexion. We use a Fisher matrix analysis to forecast the relative improvement in the mass accuracy for different assumptions on the shear and flexion signal -to -noise (S/N) ratio also varying the cluster mass, redshift, and ellipticity. It turns out that the error on the cluster mass may be reduced up to a factor ∼ 2 for reasonable values of the flexion S/N ratio. As a general result, we get that the improvement in mass accuracy is larger for more flattened haloes, but it extracting general trends is a difficult because of the many parameters at play. We nevertheless find that flexion is as efficient as magnification to increase the accuracy in both mass and concentration determination.