Gravitational Lens Statistics and the Density Profile of Dark Halos

Takahashi, Ryuichi; Chiba, Takeshi

doi:10.1086/323961

Cited by 28 publications

(32 citation statements)

References 54 publications

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“…For most surveys to date, such as JVAS/CLASS, the number of observed quasars is sufficiently small that each quasar can be returned to and observed in great detail. In such cases, for small‐to‐medium image separations the brightness of the lens system is seen as the total brightness of all the images, so the total magnification should be used in the bias (Takahashi & Chiba 2001; Cen et al 1994). However, for large angular separations, a lens system will only be identified if a second image is independently resolved in the survey, and therefore the magnification of the second brightest image should be used.…”

Section: Calculating the Image Separation Distributionmentioning

confidence: 99%

“…Statistics of strongly lensed images promise a wealth of information about luminous and dark matter distributions and the correlations between them. For example, these statistics have yielded general constraints on the radial mass profile of early‐type galaxies (Maoz & Rix 1993; Keeton 2001b; Keeton & Madau 2001; Rusin & Ma 2001; Sarbu, Rusin & Ma 2001; Takahashi & Chiba 2001; Wyithe, Turner & Spergel 2001; Oguri 2002; Oguri et al 2002; Huterer & Ma 2004; Kuhlen, Keeton & Madau 2004). Lensing by non‐spherical mass distributions shows rich phenomenology that may be used to probe the distribution of dark matter in galaxies and clusters.…”

Section: Introductionmentioning

confidence: 99%

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Effects of galaxy-halo alignment and adiabatic contraction on gravitational lens statistics

Minor

Kaplinghat

2008

Monthly Notices of the Royal Astronomical Society

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We study the strong gravitational lens statistics of triaxial cold dark matter haloes occupied by central early‐type galaxies. We calculate the image separation distribution for double, cusp and quad configurations. The ratios of image multiplicities at large separations are consistent with the triaxial NFW model, and at small separations are consistent with the singular isothermal ellipsoid model. At all the separations, the total lensing probability is enhanced by adiabatic contraction. If no adiabatic contraction is assumed, naked cusp configurations become dominant at ≈2.5 arcsec, which is inconsistent with the data. We also show that at small‐to‐moderate separations (≲5 arcsec) the image multiplicities depend sensitively on the alignment of the shapes of the luminous and dark matter projected density profiles. In contrast to other properties that affect these ratios, the degree of alignment does not have a significant effect on the total lensing probability. These correlations may therefore be constrained by comparing the theoretical image separation distribution to a sufficiently large lens sample from future wide and deep sky surveys such as Pan‐Stars, LSST and JDEM. Understanding the correlations in the shapes of galaxies and their dark matter halo is important for future weak lensing surveys.

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Section: Calculating the Image Separation Distributionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of galaxy-halo alignment and adiabatic contraction on gravitational lens statistics

Minor

Kaplinghat

2008

Monthly Notices of the Royal Astronomical Society

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“…The complementary semi‐analytic approaches often invoked simple spherically symmetric mass profiles, for calculational reasons (e.g. Hamana & Futamase 1997; Maoz et al 1997; Cooray 1999; Molikawa et al 1999; Keeton 2001; Kochanek & White 2001; Takahashi & Chiba 2001; Wyithe, Turner & Spergel 2001; Li & Ostriker 2003; Chen 2004, 2005; Huterer & Ma 2004; Kuhlen, Keeton & Madau 2004; Lopes & Miller 2004; Oguri 2006). A more advanced calculation adopted an ellipsoid for projected cluster mass distributions (Meneghetti et al 2003a; Fedeli & Bartelmann 2007; Fedeli et al 2007, 2008).…”

Section: Introductionmentioning

confidence: 99%

What is the largest Einstein radius in the universe?

Oguri

Blandford

2009

Monthly Notices of the Royal Astronomical Society

139

294

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The Einstein radius plays a central role in lens studies as it characterises the strength of gravitational lensing. The distribution of Einstein radii near the upper cutoff should probe the largest mass concentrations in the universe. Adopting a triaxial halo model, we compute expected distributions of large Einstein radii. To assess the cosmic variance, we generate a number of all-sky Monte-Carlo realisations. We find that the expected largest Einstein radius in the universe is sensitive to the cosmological model: for a source redshift z=1, they are 42^{+9}_{-7}, 35^{+8}_{-6}, and 54^{+12}_{-7} arcseconds, assuming best-fit parameters of the WMAP5, WMAP3 and WMAP1 data, respectively. These values are broadly consistent with current observations given their incompleteness. For the same source redshift, we expect in all-sky 35 (WMAP5), 15 (WMAP3), and 150 (WMAP1) clusters that have Einstein radii larger than 20". Whilst the values of the largest Einstein radii are almost unaffected by the primordial non-Gaussianity currently of interest, the abundance of large lens clusters should probe non-Gaussianity competitively with CMB, but only if other cosmological parameters are well-measured. We also find that these "superlens" clusters constitute a highly biased population. For instance, a substantial fraction of these superlens clusters have major axes preferentially aligned with the line-of-sight. As a consequence, the projected mass distributions of the clusters are rounder by an ellipticity of 0.2 and have 40%-60% larger concentrations compared with typical clusters with similar redshifts and masses. We argue that the large concentration measured in A1689 is consistent with our model prediction at the 1.2\sigma level. (Abridged)Comment: 17 pages, 12 figures, 1 table, accepted for publication in MNRA

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“…Keeton (2001) used the statistics of JVAS/CLASS lenses to indicate that CDM galaxies are too concentrated to agree with the lensing statistics, while Keeton & Madau (2001) used the absence of wide‐separation lenses in the CLASS to impose an upper bound on the concentration of dark matter haloes. Takahashi & Chiba (2001) have considered lensing by both singular isothermal sphere (SIS) and Navarro–Frenk–White (NFW) profile galaxies, and have found that the lack of observed large‐angle separation lenses indicates that the density profile is not too steep (β≲ 1.5, with ρ( r ) ∝ r −β ). Oguri, Taruya & Suto (2001) have obtained a similar result by using the statistics of tangential and radial arcs.…”

Section: Introductionmentioning

confidence: 99%

Strong lensing constraints on the velocity dispersion and density profile of elliptical galaxies

Davis

Huterer

Krauss

2003

Monthly Notices RAS

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We use the statistics of strong gravitational lensing from the Cosmic Lens All‐Sky Survey to impose constraints on the velocity dispersion and density profile of elliptical galaxies. This approach differs from much recent work, where the luminosity function, velocity dispersion and density profile have been typically assumed in order to constrain cosmological parameters. It is indeed remarkable that observational cosmology has reached the point where we can consider using cosmology to constrain astrophysics, rather than vice versa. We use two different observables to obtain our constraints: total optical depth and angular distributions of lensing events. In spite of the relatively poor statistics and the uncertain identification of lenses in the survey, we obtain interesting constraints on the velocity dispersion and density profiles of elliptical galaxies. For example, assuming the singular isothermal sphere density profile and marginalizing over other relevant parameters, we find 168 ≤σ*≤ 200 km s−1 (68 per cent confidence level), and 158 ≤σ*≤ 220 km s−1 (95 per cent confidence level). Furthermore, if we instead assume a generalized Navarro–Frenk–White density profile and marginalize over other parameters, the slope of the profile is constrained to be 1.50 ≤β≤ 2.00 (95 per cent confidence level). We also constrain the concentration parameter as a function of the density profile slope in these models. These results are essentially independent of the exact knowledge of cosmology. We briefly discuss the possible impact on these constraints of allowing the galaxy luminosity function to evolve with redshift, and also possible useful future directions for exploration.

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Gravitational Lens Statistics and the Density Profile of Dark Halos

Cited by 28 publications

References 54 publications

Effects of galaxy-halo alignment and adiabatic contraction on gravitational lens statistics

Effects of galaxy-halo alignment and adiabatic contraction on gravitational lens statistics

What is the largest Einstein radius in the universe?

Strong lensing constraints on the velocity dispersion and density profile of elliptical galaxies

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