Arc Statistics in Triaxial Dark Matter Halos: Testing the Collisionless Cold Dark Matter Paradigm

Oguri, Masamune; Lee, Jounghun; Suto, Yasushi

doi:10.1086/379223

Cited by 116 publications

(189 citation statements)

References 82 publications

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“…Both observations and simulations agree that strong lenses have high concentrations (Hennawi et al 2007;Fedeli et al 2007a;Kneib et al 2003;Gavazzi et al 2003;Broadhurst et al 2008). Triaxiality is also relevant, because clusters seen along their major axis are more efficient lenses (Oguri et al 2003). Although cluster galaxies statistically do not change the distributions of the arc properties (Meneghetti et al 2000;Flores et al 2000;Hilbert et al 2008), cD galaxies sitting at the bottom of the cluster potential well increase the ability to produce long and thin arcs by ∼30-50% (Meneghetti et al 2003a).…”

Section: Introductionmentioning

confidence: 57%

Strong lensing in the MARENOSTRUM UNIVERSE

Meneghetti

Fedeli

Pace

et al. 2010

A&A

152

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Context. Strong lensing is one of the most direct probes of mass distribution in the inner regions of galaxy clusters. It can be used to constrain the density profiles and to measure the mass of the lenses. Moreover, the abundance of strong lensing events can be used to constrain structure formation and cosmological parameters through the so-called "arc-statistics" approach. However, several issues related to the use of strong lensing clusters in cosmological applications are still controversial, leading to the suspicion that several biases may affect this very peculiar class of objects. Aims. With this study we aim a better understanding of the properties of galaxy clusters that can potentially act as strong lenses. Methods. We do so by investigating the properties of a large sample of galaxy clusters extracted from the N-body/hydrodynamical simulation MareNostrum Universe. We perform ray-tracing simulations with each of them and identify those objects capable of producing strong lensing effects. We explore the correlation between the cross section for lensing and many properties of clusters, such as mass, three-dimensional and projected shapes, their concentrations, the X-ray luminosity, and the dynamical activity. Results. We quantify the minimal cluster mass required for producing both multiple images and large distortions. While we do not measure a significant excess of triaxiality in strong lensing clusters, we find that the probability of strong alignments between the major axes of the lenses and the line of sight is a growing function of the lensing cross section. In projection, the strong lenses appear rounder within R 200 , but we find that their cores tend to be more elliptical as the lensing cross section increases. As a result of the orientation bias, we also find that the cluster concentrations estimated from the projected density profiles tend to be biased high. The X-ray luminosity of strong lensing clusters tend to be higher than for normal lenses of similar mass and redshift. This is particularly significant for the least massive lenses. Finally, we find that the strongest lenses generally exhibit an excess of kinetic energy within the virial radius, thus indicating that they are more dynamically active than the usual clusters. Conclusions. We conclude that strong lensing clusters are a very peculiar class of objects, affected by many selection biases that need to be properly modeled when using them to study the inner structure of galaxy clusters or to constrain the cosmological parameters.

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Section: Introductionmentioning

confidence: 57%

Strong lensing in the MARENOSTRUM UNIVERSE

Meneghetti

Fedeli

Pace

et al. 2010

A&A

152

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“…For instance, a very elongated halo that is directed along the line of sight can lead to a highly concentrated, projected surface mass-density profile, which causes a large tangential critical curve (see e.g. Oguri et al 2003;Dalal et al 2004;Meneghetti et al 2007Meneghetti et al , 2010. When sampling axis ratios from Eqs.…”

Section: The Impact Of Triaxialitymentioning

confidence: 99%

“…Here, assuming a fixed a sc , smaller A e correspond to smaller values of the mean concentration, and thus it is more likely that haloes have a smaller c e . Following Oguri et al (2003), we vary the value of A e between 0.8 and 1.6, with A e = 1.1 being the ΛCDM standard value, and present the resulting distributions in Fig. 8.…”

Section: The Impact Of the Inner Slope And The C-m Relationmentioning

confidence: 99%

“…On the basis of the study of Oguri et al (2003), the haloes are modelled using triaxial density profiles. By Monte Carlo (MC) sampling the distribution of the maximum for different underlying assumptions like the mass function, the allowed range of triaxiality, the inner slope and the massconcentration relation, we study the impact of different choices on the resulting distributions of the maximum.…”

Section: Introductionmentioning

confidence: 99%

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The strongest gravitational lenses

Waizmann

Redlich

Bartelmann

2012

A&A

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Context. With the amount and quality of galaxy cluster data increasing, the question arises whether or not the standard cosmological model can be questioned on the basis of a single observed extreme galaxy cluster. Usually, the word extreme refers directly to cluster mass, which is not a direct observable and thus subject to substantial uncertainty. Hence, it is desirable to extend studies of extreme clusters to direct observables, such as the Einstein radius. Aims. We aim to evaluate the occurrence probability of the large observed Einstein radius of MACS J0717.5+3745 within the standard ΛCDM cosmology. In particular, we want to model the distribution function of the single largest Einstein radius in a given cosmological volume and to study which underlying assumptions and effects have the strongest impact on the results. Methods. We obtain this distribution by a Monte Carlo approach, based on the semi-analytic modelling of the halo population on the past lightcone. After sampling the distribution, we fit the results with the general extreme value (GEV) distribution which we use for the subsequent analysis. Results. We find that the distribution of the maximum Einstein radius is particularly sensitive to the precise choice of the halo mass function, lens triaxiality, the inner slope of the halo density profile and the mass-concentration relation. Using the distributions so obtained, we study the occurrence probability of the large Einstein radius of MACS J0717.5+3745, finding that this system is not in tension with ΛCDM. We also find that the GEV distribution can be used to fit very accurately the sampled distributions and that all of them can be described by a (type-II) Fréchet distribution. Conclusions. With a multitude of effects that strongly influence the distribution of the single largest Einstein radius, it is more than doubtful that the standard ΛCDM cosmology can be ruled out on the basis of a single observation. If, despite the large uncertainties in the underlying assumptions, one wanted to do so, a much larger Einstein radius ( > ∼ 100 ) than that of MACS J0717.5+3745 would have to be observed.

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“…As a measure of the size of the tangential critical curve, it is very sensitive to a number of basic halo properties, such as the density profile, concentration, triaxiality, and the alignment of the halo with respect to the observer, but also to the lensing geometry, which is fixed by the redshifts of the lens and the sources (see e.g. Oguri et al 2003;Oguri & Blandford 2009). Moreover, the distribution of the sample of Einstein radii as a whole is strongly influenced by the underlying cosmological model.…”

Section: Introductionmentioning

confidence: 99%

The strongest gravitational lenses

Waizmann

Redlich

Meneghetti

et al. 2014

A&A

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Context. The Einstein radius of a gravitational lens is a key characteristic. It encodes information about decisive quantities such as halo mass, concentration, triaxiality, and orientation with respect to the observer. Therefore, the largest Einstein radii can potentially be utilised to test the predictions of the ΛCDM model. Aims. Hitherto, studies have focussed on the single largest observed Einstein radius. We extend those studies by employing order statistics to formulate exclusion criteria based on the n largest Einstein radii and apply these criteria to the strong lensing analysis of 12 MACS clusters at z > 0.5. Methods. We obtain the order statistics of Einstein radii by a Monte Carlo approach, based on the semi-analytic modelling of the halo population on the past lightcone. After sampling the order statistics, we fit a general extreme value distribution to the first-order distribution, which allows us to derive analytic relations for the order statistics of the Einstein radii. Results. We find that the Einstein radii of the 12 MACS clusters are not in conflict with the ΛCDM expectations. Our exclusion criteria indicate that, in order to exhibit tension with the concordance model, one would need to observe approximately twenty Einstein radii with θ eff > ∼ 30 , ten with θ eff > ∼ 35 , five with θ eff > ∼ 42 , or one with θ eff > ∼ 74 in the redshift range 0.5 ≤ z ≤ 1.0 on the full sky (assuming a source redshift of z s = 2). Furthermore, we find that, with increasing order, the haloes with the largest Einstein radii are on average less aligned along the line-of-sight and less triaxial. In general, the cumulative distribution functions steepen for higher orders, giving them better constraining power. Conclusions. A framework that allows the individual and joint order distributions of the n-largest Einstein radii to be derived is presented. From a statistical point of view, we do not see any evidence of an Einstein ring problem even for the largest Einstein radii of the studied MACS sample. This conclusion is consolidated by the large uncertainties that enter the lens modelling and to which the largest Einstein radii are particularly sensitive.

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Arc Statistics in Triaxial Dark Matter Halos: Testing the Collisionless Cold Dark Matter Paradigm

Cited by 116 publications

References 82 publications

Strong lensing in the MARENOSTRUM UNIVERSE

Strong lensing in the MARENOSTRUM UNIVERSE

The strongest gravitational lenses

The strongest gravitational lenses

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