Weak Gravitational Lensing by a Sample of X‐Ray–luminous Clusters of Galaxies. II. Comparison with Virial Masses

Irgens, R. J.; Lilje, P. B.; Dahle, H.; Maddox, S.

doi:10.1086/342751

Cited by 32 publications

(33 citation statements)

References 41 publications

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“…Our estimate of the velocity dispersion (σ V = 1302 +107 −71 km s −1 ) agrees with those of Patel et al (2000) and Irgens et al (2002) computed on a much smaller galaxy sample. This high value 4 See http://asc.harvard.edu/ciao/ Table 3).…”

Section: Discussionsupporting

confidence: 88%

“…Irgens et al (2002) confirm these measurements on the basis of 20 (unpublished) redshifts, six of them in common with those of Patel et al (2000), with z = 0.3207 ± 0.0001 and σ V = 1130 +150 −110 km s −1 . Moreover, they find good agreement between the galaxy velocity dispersion and the dark matter velocity dispersion obtained from the weak gravitational lensing analysis (σ DM = 1240 ± 80 km s −1 ).…”

Section: Introductionsupporting

confidence: 75%

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Structure of Abell 1995 from optical and X-ray data: a galaxy cluster with an elongated radio halo

Boschin

Girardi

Barrena

2012

A&A

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Context. Abell 1995 is a puzzling galaxy cluster hosting a powerful radio halo, but it has not yet been recognized as a obvious cluster merger, as usually expected for clusters with diffuse radio emission. Aims. We aim at an exhaustive analysis of the internal structure of Abell 1995 to verify that this cluster is really dynamically relaxed, as reported in previous studies. Methods. We base our analysis on new and archival spectroscopic and photometric data for 126 galaxies in the field of Abell 1995. The study of the hot intracluster medium was performed on X-ray archival data. Results. Based on 87 fiducial cluster members, we have computed the average cluster redshift z = 0.322 and the global radial velocity dispersion σ V ∼ 1300 km s −1 . We detect two main optical subclusters separated by 1.5 that cause the known NE-SW elongation of the galaxy distribution and a significant velocity gradient in the same direction. As for the X-ray analysis, we confirm that the intracluster medium is mildly elongated, but we also detect three X-ray peaks. Two X-ray peaks are offset with respect to the two galaxy peaks and lie between them, thus suggesting a bimodal merger caught in a phase of post core-core passage. The third X-ray peak lies between the NE galaxy peak and a third, minor galaxy peak suggesting a more complex merger. The difficulty of separating the two main systems leads to a large uncertainty on the line-of-sight (LOS) velocity separation and the system mass: ΔV rf,LOS = 600-2000 km s −1 and M sys = 2-5 × 10 15 h −1 70 M , respectively. Simple analytical arguments suggest a merging scenario for Abell 1995, where two main subsystems are seen just after the collision with an intermediate projection angle. Conclusions. The high mass of Abell 1995 and the evidence of merging suggest it is not atypical among clusters with known radio halos. Interestingly, our findings reinforce the previous evidence for the peculiar dichotomy between the dark matter and galaxy distributions observed in this cluster.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionsupporting

confidence: 75%

Structure of Abell 1995 from optical and X-ray data: a galaxy cluster with an elongated radio halo

Boschin

Girardi

Barrena

2012

A&A

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“…X-ray studies and virial analyses of this cluster are hence also more compatible with lensing studies (Patel et al 2000;Irgens et al 2002). The projected two-dimensional distribution of cluster galaxies in Abell 1995 is clearly elliptical (see Fig.…”

Section: Discussionsupporting

confidence: 80%

“…Analyses assuming a relaxed cluster will hence naturally differ from weak lensing analyses, where no assumption is made about the dynamical state of the cluster. One example is the virial analysis by Irgens et al (2002), where an unusually high velocity dispersion of σ v = 1680 +340 −229 km s −1 was obtained for Abell 1351, based on radial velocity measurements of 17 cluster galaxies. Such a high velocity dispersion is not uncommon in merging systems.…”

Section: Discussionmentioning

confidence: 99%

Weak lensing density profiles and mass reconstructions of the galaxy clusters Abell 1351 and Abell 1995

Holhjem

Schirmer

Dahle

2009

A&A

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Aims. The aim of the present work is to study the overall mass distribution of the galaxy clusters Abell 1351 and Abell 1995 using weak gravitational lensing. These clusters have a very different mass structure and dynamical state and are the two extremes from a larger sample of 38 X-ray luminous clusters of similar size and redshift. Methods. We measure the shear values of faint background galaxies and correct for PSF anisotropies using the KSB+ method. Twodimensional mass maps of the clusters are created using a finite-field mass reconstruction algorithm, and verified with aperture mass statistics. The masses inferred from the reconstructions are compared to those obtained from fitting spherically symmetric SIS-and NFW-models to the tangential shear profiles. We discuss the NFW concentration parameters in detail. Results. From the mass reconstructions we infer M 2D (< r 200 )-masses of 11.7 ± 3.1 × 10 14 h −1 70 M and 10.5 ± 2.7 × 10 14 h −1 70 M for Abell 1351 and Abell 1995, respectively. About 3 northeast of the main mass peak of Abell 1351, we detect a significant secondary peak both in the mass reconstruction and from aperture mass statistics. This feature is also traced by cluster members selected by means of their V − I colour, and is therefore likely a real substructure of Abell 1351. From our fits to the tangential shear we infer masses of the order of M 200 ∼ 8−9 × 10 14 h −1 70 M (Abell 1351) and M 200 ∼ 5−6 × 10 14 h −1 70 M (Abell 1995). The concentration parameters remain poorly constrained by our weak lensing analysis.

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“…2 , and ( ) K k ij is the complete elliptical integral of the first kind in Legendre's notation (form from Irgens et al 2002).…”

Section: Overdensity Dynamicsmentioning

confidence: 99%

The KMOS Cluster Survey (KCS). III. Fundamental Plane of Cluster Galaxies at z ≃ 1.80 in JKCS 041*

Prichard

Davies

Beifiori

et al. 2017

ApJ

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We present data for 16 galaxies in the overdensity JKCS 041 at z 1.80 as part of the K-band Multi-Object Spectrograph (KMOS) Cluster Survey (KCS). With 20-hour integrations, we have obtained deep absorption-line spectra from which we derived velocity dispersions for seven quiescent galaxies. We combined photometric parameters derived from Hubble Space Telescope images with the dispersions to construct a fundamental plane (FP) for quiescent galaxies in JKCS 041. From the zero-point evolution of the FP, we derived a formation redshift for the galaxies of z f orm = 3.0±0.3, corresponding to a mean age of 1.4 ± 0.2 Gyrs. We tested the effect of structural and velocity dispersion evolution on our FP zero point and found a negligible contribution when using dynamical mass-normalized parameters (∼ 3%), but a significant contribution from stellar-mass-normalized parameters (∼ 42%). From the relative velocities of the galaxies, we probed the three-dimensional structure of these 16 confirmed members of JKCS 041, and found that a group of galaxies in the south west of the overdensity had systematically higher velocities. We derived ages for the galaxies in the different groups from the FP. We found the east-extending group had typically older galaxies (2.1 +0.3 −0.2 Gyrs), than those in the south-west group (0.3 ± 0.2 Gyrs). Although based on small numbers, the overdensity dynamics, morphology, and age results could indicate that JKCS 041 is in formation and may comprise two merging groups of galaxies. The result could link large-scale structure to ages of galaxies for the first time at this redshift.

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Weak Gravitational Lensing by a Sample of X‐Ray–luminous Clusters of Galaxies. II. Comparison with Virial Masses

Cited by 32 publications

References 41 publications

Structure of Abell 1995 from optical and X-ray data: a galaxy cluster with an elongated radio halo

Structure of Abell 1995 from optical and X-ray data: a galaxy cluster with an elongated radio halo

Weak lensing density profiles and mass reconstructions of the galaxy clusters Abell 1351 and Abell 1995

The KMOS Cluster Survey (KCS). III. Fundamental Plane of Cluster Galaxies at z ≃ 1.80 in JKCS 041*

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