Weak‐Lensing Mass Reconstruction of the Interacting Cluster 1E 0657−558: Direct Evidence for the Existence of Dark Matter

Clowe, Douglas; Gonzalez, Anthony H.; Markevitch, M.

doi:10.1086/381970

Cited by 596 publications

(694 citation statements)

References 38 publications

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“…Since dark matter was modelled with a cusped profile, whereas the galaxy density was fitted with a cored distribution, the comparison cannot be extended to the remaining parameters. The agreement provides additional evidence of the collisionless nature of dark matter, as suggested by observations of the bullet cluster (Clowe et al 2004). This time, we have been able to establish that the agreement between galaxies and dark matter concerns not only the location but also the shape of the distribution.…”

Section: Collisionless Dark Mattersupporting

confidence: 73%

A multiwavelength strong lensing analysis of baryons and dark matter in the dynamically active cluster AC 114

Sereno

Lubini

Jetzer

2010

A&A

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Context. Strong lensing studies can provide detailed mass maps of the inner regions even in dynamically active galaxy clusters. Aims. We illustrate the important role of a proper modelling of the intracluster medium, i.e., the main baryonic component. We demonstrate that the addition of a new contribution accounting for the gas can increase the statistical significance of the lensing model. Methods. We propose a parametric method for strong lensing analyses that exploits multiwavelength observations. The mass model accounts for cluster-sized dark matter halos, galaxies (whose stellar mass can be obtained from optical analyses), and the intracluster medium. The gas distribution is fitted to lensing data exploiting prior knowledge from X-ray observations. This gives an unbiased insight into each matter component and allows us to study the dynamical status of a cluster. The method was applied to AC 114, an irregular X-ray cluster. Results. We find positive evidence of dynamical activity, the dark matter distribution being shifted and rotated with respect to the gas. On the other hand, the dark matter follows the galaxy density in terms of both shape and orientation, illustrating the collisionless nature of dark matter. The inner region ( < ∼ 250 kpc) is underluminous in optical bands, whereas the gas fraction (∼20 ± 5%) slightly exceeds typical values. Evidence of lensing and X-ray suggests that the cluster develops in the plane of the sky and is not affected by the lensing over-concentration bias. Despite the dynamical activity, the matter distribution seems to agree with predictions of N-body simulations. An universal cusped profile provides a good description of either the overall or the dark matter distribution, whereas theoretical scaling relations seem to be accurately fitted.

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Section: Collisionless Dark Mattersupporting

confidence: 73%

A multiwavelength strong lensing analysis of baryons and dark matter in the dynamically active cluster AC 114

Sereno

Lubini

Jetzer

2010

A&A

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“…It consists of two components, one main cluster and a smaller subcluster. Clowe et al (2004) fitted the main cluster to a NFW profile and measured the mass of the subcluster using aperture densitometry (Clowe et al 2000;Fahlman et al 1994). -Abell 2744 is made up of two subclusters aligned along the line-of-sight (Boschin et al 2006).…”

Section: Cluster Lens Models and Number Countsmentioning

confidence: 99%

A LABOCA survey of submillimeter galaxies behind galaxy clusters

Johansson

Sigurdarson

Horellou

2011

A&A

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Context. Submillimeter galaxies are a population of dusty star-forming galaxies at high redshift. Measuring their properties will help relate them to other types of galaxies, both at high and low redshift. This is needed in order to understand the formation and evolution of galaxies. Aims. The aim is to use gravitational lensing by galaxy clusters to probe the faint and abundant submillimeter galaxy population down to a lower flux density level than what can be achieved in blank-field observations. Methods. We use the LABOCA bolometer camera on the APEX telescope to observe five clusters of galaxies at a wavelength of 870 μm. The final maps have an angular resolution of 27.5 and a point source noise level of 1.2-2.2 mJy. We model the mass distribution in the clusters as superpositions of spherical NFW halos and derive magnification maps that we use to calculate intrinsic flux densities as well as area-weighted number counts. We also use the positions of Spitzer MIPS 24 μm sources in four of the fields for a stacking analysis. Results. We detected 37 submm sources, out of which 14 have not been previously reported. One source has a sub-mJy intrinsic flux density. The derived number counts are consistent with previous results, after correction for gravitational magnification and completeness levels. The stacking analysis reveals an intrinsic 870 μm signal of 390 ± 27 μJy at 14.5σ significance. We study the S 24 μm -S 870 μm relation by stacking on subsamples of the 24 μm sources and find a linear relation at S 24 μm < 300 μJy, followed by a flattening at higher 24 μm flux densities. The signal from the significantly detected sources in the maps accounts for 13% of the Extragalactic Background Light discovered by COBE, and the stacked signal accounts for 11%.

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“…For this reason, the interplay between baryons and dark matter, and its effects on the cluster internal structure, is less important in these than in smaller and older objects. Thus, they are ideal systems for testing the predictions of the cold-dark-matter paradigm on the internal structure of dark-matter halos (Yoshida et al 2000;Clowe et al 2004;Markevitch et al 2004;Sand et al 2008). Moreover, their mass function is highly sensitive to cosmology, since its evolution traces the growth of the linear density perturbations with exponential magnification (Press & Schechter 1974;Sheth & Tormen 2002;Jenkins et al 2001;Warren et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Weighing simulated galaxy clusters using lensing and X-ray

Meneghetti

Rasia

Merten

et al. 2010

A&A

292

409

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Context. Among the methods employed to measure the mass of galaxy clusters, the techniques based on lensing and X-ray analyses are perhaps the most widely used; however, the comparison between these mass estimates is often difficult and, in several clusters, the results apparently inconsistent. Aims. We aim at investigating potential biases in lensing and X-ray methods to measure the cluster mass profiles. Methods. We performed realistic simulations of lensing and X-ray observations that were subsequently analyzed using observational techniques. The resulting mass estimates were compared with the input models. Three clusters obtained from state-of-the-art hydrodynamical simulations, each of which projected along three independent lines-of-sight, were used for this analysis. Results. We find that strong lensing models can be trusted over a limited region around the cluster core. Extrapolating the strong lensing mass models to outside the Einstein ring can lead to significant biases in the mass estimates, if the BCG is not modeled properly, for example. Weak-lensing mass measurements can be strongly affected by substructures, depending on the method implemented to convert the shear into a mass estimate. Using nonparametric methods which combine weak and strong lensing data, the projected masses within R 200 can be constrained with a precision of ∼10%. Deprojection of lensing masses increases the scatter around the true masses by more than a factor of two because of cluster triaxiality. X-ray mass measurements have much smaller scatter (about a factor of two less than the lensing masses), but they are generally biased toward low values between 5 and 10%. This bias is entirely ascribable to bulk motions in the gas of our simulated clusters. Using the lensing and the X-ray masses as proxies for the true and the hydrostatic equilibrium masses of the simulated clusters and by averaging over the cluster sample, we are able to measure the lack of hydrostatic equilibrium in the systems we have investigated. Conclusions. Although the comparison between lensing and X-ray masses may be difficult in individual systems due to triaxiality and substructures, using a large number of clusters with both lensing and X-ray observations may lead to important information about their gas physics and allow use of lensing masses to calibrate the X-ray scaling relations.

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Weak‐Lensing Mass Reconstruction of the Interacting Cluster 1E 0657−558: Direct Evidence for the Existence of Dark Matter

Cited by 596 publications

References 38 publications

A multiwavelength strong lensing analysis of baryons and dark matter in the dynamically active cluster AC 114

A multiwavelength strong lensing analysis of baryons and dark matter in the dynamically active cluster AC 114

A LABOCA survey of submillimeter galaxies behind galaxy clusters

Weighing simulated galaxy clusters using lensing and X-ray

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