Dark matter in MS 1224 from distortion of background galaxies

Fahlman, G. G.; Kaiser, Nick; Squires, G.; Woods, David

doi:10.1086/174974

Cited by 219 publications

(243 citation statements)

References 14 publications

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“…We find that the tangential shear profile at large radii (r > 200 ) is well described by a singular isothermal sphere (SIS) with σ v = 987 ± 49 km s −1 , which is consistent with the estimate of 1028 ± 80 km s −1 from M07. We estimate that the aperture mass (Fahlman et al 1994) within r = 710 kpc is (4.47 ± 0.48) × 10 14 M , again statistically consistent with the previous measurement (5.00 ± 0.55) × 10 14 M .…”

Section: Mass Luminosity and Significance Estimationsupporting

confidence: 91%

A STUDY OF THE DARK CORE IN A520 WITH THEHUBBLE SPACE TELESCOPE: THE MYSTERY DEEPENS

Jee

Mahdavi

Hoekstra

et al. 2012

ApJ

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We present a Hubble Space Telescope/Wide Field Planetary Camera 2 weak-lensing study of A520, where a previous analysis of ground-based data suggested the presence of a dark mass concentration. We map the complex mass structure in much greater detail, leveraging more than a factor of three increase in the number density of source galaxies available for lensing analysis. The "dark core" that is coincident with the X-ray gas peak, but not with any stellar luminosity peak, is now detected with more than 10σ significance. The ∼1.5 Mpc filamentary structure elongated in the NE-SW direction is also clearly visible. Taken at face value, the comparison among the centroids of dark matter, intracluster medium, and galaxy luminosity is at odds with what has been observed in other merging clusters with a similar geometric configuration. To date, the most remarkable counterexample might be the Bullet Cluster, which shows a distinct bow-shock feature as in A520, but no significant weak-lensing mass concentration around the X-ray gas. With the most up-to-date data, we consider several possible explanations that might lead to the detection of this peculiar feature in A520. However, we conclude that none of these scenarios can be singled out yet as the definite explanation for this puzzle.

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Section: Mass Luminosity and Significance Estimationsupporting

confidence: 91%

A STUDY OF THE DARK CORE IN A520 WITH THEHUBBLE SPACE TELESCOPE: THE MYSTERY DEEPENS

Jee

Mahdavi

Hoekstra

et al. 2012

ApJ

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“…The lower panels of Fig. 8 show the size (r h )-magnitude (i AB ) diagram (Fahlman et al 1994). Due to statistical measurement errors of r h and to the large PSF variation over the MegaCam field of view the dispersion of the r h distribution is broad.…”

Section: Size Selectionmentioning

confidence: 99%

Photometric redshifts for the CFHTLS T0004 deep and wide fields

Coupon¹,

Ilbert

Kilbinger³

et al. 2009

A&A

189

303

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Aims. We compute photometric redshifts in the fourth public release of the Canada-France-Hawaii Telescope Legacy Survey. This unique multi-colour catalogue comprises u * , g , r , i , z photometry in four deep fields of 1 deg 2 each and 35 deg 2 distributed over three wide fields. Methods. We used a template-fitting method to compute photometric redshifts calibrated with a large catalogue of 16 983 high-quality spectroscopic redshifts from the VVDS-F02, VVDS-F22, DEEP2, and the zCOSMOS surveys. The method includes correction of systematic offsets, template adaptation, and the use of priors. We also separated stars from galaxies using both size and colour information.Results. Comparing with galaxy spectroscopic redshifts, we find a photometric redshift dispersion, σ Δz/(1+zs) , of 0.028-0.30 and an outlier rate, |Δz| ≥ 0.15 × (1 + z s ), of 3-4% in the deep field at i AB < 24. In the wide fields, we find a dispersion of 0.037-0.039 and an outlier rate of 3-4% at i AB < 22.5. Beyond i AB = 22.5 in the wide fields the number of outliers rises from 5% to 10% at i AB < 23 and i AB < 24, respectively. For the wide sample the systematic redshift bias stays below 1% to i AB < 22.5, whereas we find no significant bias in the deep fields. We investigated the effect of tile-to-tile photometric variations and demonstrated that the accuracy of our photometric redshifts is reduced by at most 21%. Application of our star-galaxy classifier reduced the contamination by stars in our catalogues from 60% to 8% at i AB < 22.5 in our field with the highest stellar density while keeping a complete galaxy sample. Our CFHTLS T0004 photometric redshifts are distributed to the community. Our release includes 592 891 (i AB < 22.5) and 244 701 (i AB < 24) reliable galaxy photometric redshifts in the wide and deep fields, respectively.

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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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Dark matter in MS 1224 from distortion of background galaxies

Cited by 219 publications

References 14 publications

A STUDY OF THE DARK CORE IN A520 WITH THEHUBBLE SPACE TELESCOPE: THE MYSTERY DEEPENS

A STUDY OF THE DARK CORE IN A520 WITH THEHUBBLE SPACE TELESCOPE: THE MYSTERY DEEPENS

Photometric redshifts for the CFHTLS T0004 deep and wide fields

A LABOCA survey of submillimeter galaxies behind galaxy clusters

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