Unlensing Multiple Arcs in 0024+1654: Reconstruction of the Source Image

Colley, Wesley N.; Tyson, J. A.; Turner, Edwin L.

doi:10.1086/310015

Cited by 67 publications

(84 citation statements)

References 19 publications

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“…1) that were first observed by Koo (1988) and subsequently studied by Mellier et al (1991), Kassiola et al (1994), Wallington et al (1995) and Smail et al (1997). The main arc is split into segments (Colley et al 1996;Tyson et al 1998) and is the lensed image of a background blue galaxy at redshift z = 1.675 (Broadhurst et al 2000). Unlike other clusters of galaxies, such as Abell 2218 or Abell 2390 that have arclike features, Cl 0024+1654 does not have a central dominant cD galaxy.…”

Section: The Clustermentioning

confidence: 94%

An ISOCAM survey through gravitationally lensing galaxy clusters

Metcalfe

Kneib²,

McBreen³

et al. 2005

A&A

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Abstract.Observations of the core of the massive cluster Cl 0024+1654, at a redshift z ∼ 0.39, were obtained with the Infrared Space Observatory using ISOCAM at 6.7 µm (hereafter 7 µm) and 14.3 µm (hereafter 15 µm). Thirty five sources were detected at 15 µm and thirteen of them are spectroscopically identified with cluster galaxies. The remaining sources consist of four stars, one quasar, one foreground galaxy, three background galaxies and thirteen sources with unknown redshift. The sources with unknown redshift are all likely to be background sources that are gravitationally lensed by the cluster. The spectral energy distributions (SEDs) of twelve cluster galaxies were fit from a selection of 20 models using the program GRASIL. The ISOCAM sources have best-fit SEDs typical of spiral or starburst models observed 1 Gyr after the main starburst event. The star formation rates were obtained for cluster members. The median infrared luminosity of the twelve cluster galaxies is ∼1.0 × 10 11 L , with 10 having infrared luminosity above 9 × 10 10 L , and so lying near or above the 1 × 10 11 L threshold for identification as a luminous infrared galaxy (LIRG). The [O ] star formation rates obtained for 3 cluster galaxies are one to two orders of magnitude lower than the infrared values, implying that most of the star formation is missed in the optical because it is enshrouded by dust in the starburst galaxy. The cluster galaxies in general are spatially more concentrated than those detected at 15 µm. However the velocity distributions of the two categories are comparable. The colour−magnitude diagramme is given for the galaxies within the ISOCAM map. Only 20% of the galaxies that are significantly bluer than the cluster main sequence were detected at 15 µm, to the limiting sensitivity recorded. The counterparts of about half of the 15 µm cluster sources are blue, luminous, star-forming systems and the type of galaxy that is usually associated with the Butcher-Oemler effect. HST images of these galaxies reveal a disturbed morphology with a tendency for an absence of nearby companions. Surprisingly the counterparts of the remaining 15 µm cluster galaxies lie on the main sequence of the colour-magnitude diagramme. However in HST images they all have nearby companions and appear to be involved in interactions and mergers. Dust obscuration may be a major cause of the 15 µm sources appearing on the cluster main sequence. The majority of the ISOCAM sources in the Butcher-Oemler region of the colourmagnitude diagram are best fit by spiral-type SEDs whereas post-starburst models are preferred on the main sequence, with the starburst event probably triggered by interaction with one or more galaxies. Finally, the mid-infrared results on Cl 0024+1654 are compared with four other clusters observed with ISOCAM. Scaling the LIRG count in Cl 0024+1654 to the clusters Abell 370, Abell 1689, Abell 2218 and Abell 2390 with reference to their virial radii, masses, distances, and the sky area scanned in each case, we compared the number o...

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Section: The Clustermentioning

confidence: 94%

An ISOCAM survey through gravitationally lensing galaxy clusters

Metcalfe

Kneib²,

McBreen³

et al. 2005

A&A

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“…2 10 2⌺ will produce gravitational lensing of multiple images, where the source and the observer are connected by more than one null geodesic, and two or more images of a background quasar (first discovered by Walsh, Carswell, & Weyman 1979) or galaxy (for an impressive recent example see Colley, Turner, & Tyson 1995) can be seen. This happens along a trivial fraction of lines of sight estimated to be a fraction 13 ϫ 10 Ϫ3 from observations of double quasars.…”

mentioning

confidence: 99%

Effects of Weak Gravitational Lensing from Large-Scale Structure on the Determination of [CLC][ITAL]q[/ITAL][TINF]0[/TINF][/CLC]

Wambsganß

Cen

et al. 1997

The Astrophysical Journal

126

146

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Weak gravitational lensing by large-scale structure affects the determination of the cosmological deceleration parameter q 0 . We find that the lensing induced dispersions on truly standard candles are 0.04 and 0.02 mag at redshift z ϭ 1 and z ϭ 0.5, respectively, in a COBE-normalized cold dark matter universe with ⍀ 0 ϭ 0.40, ⌳ 0 ϭ 0.6, H ϭ 65 km s Ϫ1 Mpc Ϫ1, and 8 ϭ 0.79. It is shown that one would observe q 0 ϭ Ϫ0.395 Ϫ0.095 ϩ0.125 and q 0 ϭ Ϫ0.398 Ϫ0.077 ϩ0.048 (the error bars are 2 limits) with standard candles with zero intrinsic dispersion at redshift z ϭ 1 and z ϭ 0.5, respectively, compared to the truth of q 0 ϭ Ϫ0.400. A standard COBE normalized ⍀ 0 ϭ 1 CDM model would produce three times as much variance and a mixed (hot and cold) dark matter model would lead to an intermediate result. One unique signature of this dispersion effect is its non-Gaussianity. Although the lensing induced dispersion at lower redshift is still significantly smaller than the currently best observed (total) dispersion of 0.12 mag in a sample of type Ia supernovae, selected with the multicolor light curve shape method, it becomes significant at higher redshift. We show that there is an optimal redshift, in the range z 1 0.5-2.0 depending on the amplitude of the intrinsic dispersion of the standard candles, at which q 0 can be most accurately determined.

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“…Four strongly lensed arcs can be clearly seen around the tangential critical curve (see also, Smail et al 1996;Broadhurst et al 2000). These arcs have been used to constrain the mass in the central region of the cluster (Colley et al 1996;Tyson et al 1998;Broadhurst et al 2000;Comerford et al 2006). These mass constraints have been compared with those derived from X-ray measurements with Chandra (Ota et al 2004) and XMM-Newton (Zhang et al 2005).…”

Section: A Ring Of Dark Matter Around Cl0024+17?mentioning

confidence: 99%

Systematics in lensing reconstruction: dark matter rings in the sky?

Ponente

Diego

2011

A&A

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Context. Non-parametric lensing methods are a useful way of reconstructing the lensing mass of a cluster without making assumptions about the way the mass is distributed in the cluster. These methods are particularly powerful in the case of galaxy clusters with a large number of constraints. The advantage of not assuming implicitly that the luminous matter follows the dark matter is particularly interesting in those cases where the cluster is in a non-relaxed dynamical state. On the other hand, non-parametric methods have several limitations that should be taken into account carefully. Aims. We explore some of these limitations and focus on their implications for the possible ring of dark matter around the galaxy cluster CL0024+17. Methods. We project three background galaxies through a mock cluster of known radial profile density and obtain a map for the arcs (θ map). We also calculate the shear field associated with the mock cluster across the whole field of view (3.3 arcmin). Combining the positions of the arcs and the two-direction shear, we perform an inversion of the lens equation using two separate methods, the biconjugate gradient, and the quadratic programming (QADP) to reconstruct the convergence map of the mock cluster. Results. We explore the space of the solutions of the convergence map and compare the radial density profiles to the density profile of the mock cluster. When the inversion matrix algorithms are forced to find the exact solution, we encounter systematic effects resembling ring structures, that clearly depart from the original convergence map. Conclusions. Overfitting lensing data with a non-parametric method can produce ring-like structures similar to the alleged one in CL0024.

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Unlensing Multiple Arcs in 0024+1654: Reconstruction of the Source Image

Cited by 67 publications

References 19 publications

An ISOCAM survey through gravitationally lensing galaxy clusters

An ISOCAM survey through gravitationally lensing galaxy clusters

Effects of Weak Gravitational Lensing from Large-Scale Structure on the Determination of [CLC][ITAL]q[/ITAL][TINF]0[/TINF][/CLC]

Systematics in lensing reconstruction: dark matter rings in the sky?

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