Strong lensing in Abell 1703: constraints on the slope of the inner dark matter distribution (original) (raw)
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Astronomy & Astrophysics, 2022
Aims. From accurate photometric and spectroscopic information, we build the Fundamental Plane (FP) relation for the early-type galaxies of the cluster Abell S1063. We use this relation to develop an improved strong lensing model of the cluster, and we decompose the cluster’s cumulative projected total mass profile into its stellar, hot gas, and dark matter mass components. We compare our results with the predictions of cosmological simulations. Methods. We calibrate the FP using Hubble Frontier Fields photometry and data from the Multi Unit Spectroscopic Explorer on the Very Large Telescope. The FP allows us to determine the velocity dispersions of all 222 cluster members included in the model from their measured structural parameters. As for their truncation radii, we test a proportionality relation with the observed half-light radii. Fixing the mass contribution of the hot gas component from X-ray data, the mass density distributions of the diffuse dark matter haloes are optimised...
Testing phenomenological and theoretical models of dark matter density profiles with galaxy clusters
Monthly Notices of the Royal Astronomical Society, 2013
We use the stacked gravitational lensing mass profile of four high-mass (M 10 15 M ⊙ ) galaxy clusters around z ≈ 0.3 from Umetsu et al. to fit density profiles of phenomenological [Navarro-Frenk-White (NFW), Einasto, Sérsic, Stadel, Baltz-Marshall-Oguri (BMO) and Hernquist] and theoretical (non-singular Isothermal Sphere, DARKexp and Kang & He) models of the dark matter distribution. We account for large-scale structure effects, including a 2-halo term in the analysis. We find that the BMO model provides the best fit to the data as measured by the reduced χ 2 . It is followed by the Stadel profile, the generalized NFW profile with a free inner slope and by the Einasto profile. The NFW model provides the best fit if we neglect the 2-halo term, in agreement with results from Umetsu et al. Among the theoretical profiles, the DARKexp model with a single form parameter has the best performance, very close to that of the BMO profile. This may indicate a connection between this theoretical model and the phenomenology of dark matter halos, shedding light on the dynamical basis of empirical profiles which emerge from numerical simulations.
The Distribution of Dark Matter Over Three Decades in Radius in the Lensing Cluster Abell 611
The Astrophysical Journal, 2009
We present a detailed analysis of the baryonic and dark matter distribution in the lensing cluster Abell 611 (z=0.288), with the goal of determining the dark matter profile over an unprecedented range of cluster-centric distance. By combining three complementary probes of the mass distribution, weak lensing from multi-color Subaru imaging, strong lensing constraints based on the identification of multiply-imaged sources in Hubble Space Telescope images, and resolved stellar velocity dispersion measures for the brightest cluster galaxy (BCG) secured using the Keck telescope, we extend the methodology for separating the dark and baryonic mass components introduced by Sand et al. (2008). Our resulting dark matter profile samples the cluster from ∼3 kpc to 3.25 Mpc, thereby providing an excellent basis for comparisons with recent numerical models. We demonstrate that only by combining our three observational techniques can degeneracies in constraining the form of the dark matter profile be broken on scales crucial for detailed comparisons with numerical simulations. Our analysis reveals that a simple Navarro, Frenk, and White (NFW) profile is an unacceptable fit to our data. We confirm earlier claims based on less extensive analyses of other clusters that the inner profile of the dark matter profile deviates significantly from the NFW form and find a inner logarithmic slope β flatter than 0.3 (68%; where ρ DM ∝ r −β at small radii). In order to reconcile our data with cluster formation in a ΛCDM cosmology, we speculate that it may be necessary to revise our understanding of the nature of baryon-dark matter interactions in cluster cores. Comprehensive weak and strong lensing data, when coupled with kinematic information on the brightest cluster galaxy, can readily be applied to a larger sample of clusters to test the universality of these results.
Monthly Notices of the Royal Astronomical Society, 2012
We construct a fully self-consistent mass model for the lens galaxy SDSS J2141 at redshift 0.14, and use it to improve on previous studies by modelling its gravitational lensing effect, gas rotation curve and stellar kinematics simultaneously. We adopt a very flexible axisymmetric mass model constituted by a generalized NFW dark matter halo and a stellar mass distribution obtained by deprojecting the multi-Gaussian expansion (MGE) fit to the highresolution K'-band Laser Guide Star Adaptive Optics (LGSAO) imaging data of the galaxy, with the (spatially constant) mass-to-light ratio as a free parameter. We model the stellar kinematics by solving the anisotropic Jeans equations. We find that the inner logarithmic slope of the dark halo is weakly constrained, i.e. γ = 0.82 +0.65 −0.54 , and consistent with an unmodified NFW profile; we can conclude, however, that steep profiles (γ 1.5) are disfavoured (< 14% posterior probability). We marginalize over this parameter to infer the galaxy to have (i) a dark matter fraction within 2.2 disk radii of 0.28 +0.15 −0.10 , independent of the galaxy stellar population, implying a maximal disk for SDSS J2141; (ii) an apparently uncontracted dark matter halo, with concentration c −2 = 7.7 +4.2 −2.5 and virial velocity v vir = 242 +44 −39 km s −1 , consistent with ΛCDM predictions; (iii) a slightly oblate halo (q h = 0.75 +0.27 −0.16), consistent with predictions from baryon-affected models. Comparing the tightly constrained gravitational stellar mass inferred from the combined analysis (log 10 M ⋆ /M ⊙ = 11.12 +0.05 −0.09) with that inferred from stellar populations modelling of the galaxies colours, and accounting for an expected cold gas fraction of 20 ± 10 per cent, we determine a preference for a Chabrier IMF over Salpeter IMF by a Bayes factor of 5.7 (corresponding to substantial evidence). We infer a value β z ≡ 1 − σ 2 z /σ 2 R = 0.43 +0.08 −0.11 for the orbital anisotropy parameter in the meridional plane, in agreement with most studies of local disk galaxies, and ruling out at 99 per cent confidence level that the dynamics of this system can be described by a two-integral distribution function.
Dark Matter and Baryons in the X‐Ray Luminous Merging Galaxy Cluster RX J1347.5−1145
The Astrophysical Journal, 2008
The galaxy cluster RX J1347.5−1145 is one of the most X-ray luminous and most massive clusters known. Its extreme mass makes it a prime target for studying issues addressing cluster formation and cosmology. Despite the naive expectation that mass estimation for this cluster should be straightforward (high mass and favorable redshift make it an efficient lens, and in addition it is bright in X-rays and appears to be in a fairly relaxed state), some studies have reported very discrepant mass estimates from X-ray, dynamical and gravitational lensing. In this paper we present new high-resolution HST/ACS and Chandra X-ray data. The high resolution and sensitivity of ACS enabled us to detect and quantify several new multiply imaged sources, we now use a total of eight for the strong lensing analysis. Combining this information with shape measurements of weak lensing sources in the central regions of the cluster, we derive a high-resolution, absolutely-calibrated mass map. This map provides the best available quantification of the total mass of the central part of the cluster to date. We compare the reconstructed mass with that inferred from the new Chandra X-ray data, and conclude that both mass estimates agree extremely well in the observed region, namely within 400h −1 70 kpc of the cluster center. In addition we study the major baryonic components (gas and stars) and hence derive the dark matter distribution in the center of the cluster. We find that the dark matter and baryons are both centered on the BCG within the uncertainties (alignment is better than < 10 kpc). We measure the corresponding 1-D profiles and find that dark matter distribution is consistent with both NFW and cored profiles, indicating that a more extended radial analysis is needed to pinpoint the concentration parameter, and hence the inner slope of the dark matter profile.
Galaxy clustering and galaxy-galaxy lensing: a promising union to constrain cosmological parameters
Monthly Notices of the Royal Astronomical Society, 2009
Galaxy clustering and galaxy-galaxy lensing probe the connection between galaxies and their dark matter haloes in complementary ways. Since the clustering of dark matter haloes depends on cosmology, the halo occupation statistics inferred from the observed clustering properties of galaxies are degenerate with the adopted cosmology. Consequently, different cosmologies imply different mass-to-light ratios for dark matter haloes. Galaxy-galaxy lensing, which yields direct constraints on the actual mass-tolight ratios, can therefore be used to break this degeneracy, and thus to constrain cosmological parameters. In this paper we establish the link between galaxy luminosity and dark matter halo mass using the conditional luminosity function (CLF), Φ(L|M )dL, which gives the number of galaxies with luminosities in the range L±dL/2 that reside in a halo of mass M . We constrain the CLF parameters using the galaxy luminosity function and the luminosity dependence of the correlation lengths of galaxies. The resulting CLF models are used to predict the galaxy-galaxy lensing signal. For a cosmology that agrees with constraints from the cosmic microwave background, i.e. (Ω m , σ 8 ) = (0.238, 0.734), the model accurately fits the galaxy-galaxy lensing data obtained from the SDSS. For a comparison cosmology with (Ω m , σ 8 ) = (0.3, 0.9), however, we can accurately fit the luminosity function and clustering properties of the galaxy population, but the model predicts mass-to-light ratios that are too high, resulting in a strong overprediction of the galaxy-galaxy lensing signal. We conclude that the combination of galaxy clustering and galaxy-galaxy lensing is a powerful probe of the galaxy-dark matter connection, with the potential to yield tight constraints on cosmological parameters. Since this method mainly probes the mass distribution on relatively small (non-linear) scales, it is complementary to constraints obtained from the galaxy power-spectrum, which mainly probes the large-scale (linear) matter distribution.
The Astrophysical Journal, 2007
We present a weak gravitational lensing analysis of 22 early-type (strong) lens galaxies, based on deep Hubble Space Telescope images obtained as part of the Sloan Lens ACS Survey. Using advanced techniques to control systematic uncertainties related to the variable point spread function and charge transfer efficiency of the Advanced Camera for Surveys (ACS), we show that weak lensing signal is detected out to the edge of the Wide Field Camera ( 300 h −1 kpc at the mean lens redshift z = 0.2). We analyze blank control fields from the COSMOS survey in the same manner, inferring that the residual systematic uncertainty in the tangential shear is less than 0.3%. A joint strong and weak lensing analysis shows that the average total mass density profile is consistent with isothermal (i.e. ρ ∝ r −2 ) over two decades in radius (3-300 h −1 kpc, approximately 1-100 effective radii). This finding extends by over an order of magnitude in radius previous results, based on strong lensing and/or stellar dynamics, that luminous and dark component "conspire" to form an isothermal mass distribution. In order to disentangle the contributions of luminous and dark matter, we fit a twocomponent mass model (de Vaucouleurs + Navarro Frenk & White) to the weak and strong lensing constraints. It provides a good fit to the data with only two free parameters; i) the average stellar mass-to-light ratio M * /L V = 4.48±0.46 hM ⊙ /L ⊙ (at z = 0.2), in agreement with that expected for an old stellar population; ii) the average virial mass-to-light ratio M vir /L V = 246 +101 −87 hM ⊙ /L ⊙ . Taking into account the scatter in the mass-luminosity relation, this latter result is in good agreement with semi-analytical models of massive galaxies formation. The dark matter fraction inside the sphere of radius the effective radius is found to be 27±4%. Our results are consistent with galaxy-galaxy lensing studies of early-type galaxies that are not strong lenses, in the region of overlap (30-300 h −1 kpc). Thus, within the uncertainties, our results are representative of early-type galaxies in general.
On the Mass Profile of Galaxy Cluster C[CLC]l[/CLC] 0024+1654 Inferred from Strong Lensing
Astrophysical Journal, 2000
Observations of a flat density profile in the cores of dark-matter-dominated halos on the two extremes of mass for virialized objects in the universe, dwarf galaxies and galaxy clusters, present a serious challenge to the current standard theory of structure formation involving Cold Dark Matter (CDM). By contrast, N-body simulations of halo formation in the latter indicate density profiles which are singular and steeply rising towards the center. A flat-density core on the cluster scale is indicated by gravitational lensing observations, most significantly by the strong-lensing measurements of CL 0024+1654 by the Hubble Space Telescope. A recent re-analysis of this cluster has suggested that a uniform-density core is not demanded by the data, thereby eliminating a significant piece of the conflict between the observations and the CDM theoretical predictions. We show here, however, that the singular mass profile which that analysis reports as consistent with the lensing measurements of CL 0024+1654 implies a velocity dispersion which is much higher than the measured value for this cluster.
Monthly Notices of the Royal Astronomical Society, 2015
In this article we investigate the outer and inner mass distributions of the irregular galaxies UGC 4284 and UGC 11861, taking advantage of published HI and Hα high resolution rotation curves and constraining the stellar disk of both galaxies throughout stellar population synthesis studies. In addition we take into account the gas content of both galaxies deriving the HI+He rotation curve. The deduced baryonic rotation curves (star+gas) are inadequate to account for the total mass of UGC 4284 and UGC 11861, for that reason we examine the possibility of dark matter to explain the incongruity between the observed HI and Hα rotation curves of UGC 4284 and UGC 11861 and the derived baryonic rotation curves. We consider NFW, Burkert, DiCintio, Einasto, and the Stadel dark matter halos, to analyse the dark matter content of UGC 4284 and UGC 11861. The principal results of this work are that cored dark matter models better reproduce the dark matter Hα and HI rotation curves of UGC 11861 and the dark matter HI rotation curve of UGC 4284, while, the Hα rotation curve of UGC 4284 is better reproduced by a cuspy DiCintio DM model. In general, cored exponential two-parameters models Einasto and Stadel, give better fits than Burkert. This trend, as well as to confirm past results, presents for the first time a comparison between two different exponential dark matter models, Einasto and Stadel, in an attempt to better constrain the range of possible exponential dark matter models applied to real galaxies.
Some astrophysical implications of dark matter and gas profiles in a new galaxy cluster model
Astronomy and Astrophysics, 2005
proposed a new dynamical model for the mass density profile of clusters of galaxies as a result of a set of high resolution hydrodynamical simulations of structure formation. We investigate the lensing properties of this model evaluating the deflection angle, the lensing potential and the amplification of the images. We give particular attention to the structure and position of the critical curves to see whether this model is able to produce radial and tangential arcs. With this aim we also investigate the effect of taking into account the brightest cluster galaxy in the lensing potential and the deviations from spherical symmetry mimicked by an external shear. We also analyze the implication of the gas density and temperature profiles of the model for the properties of the X-ray emission and the comptonization parameter that determines the CMBR temperature decrement due to the Sunyaev-Zel'dovich effect.