Remarkable gravitational lensing by the galaxy cluster Abell 3827

Physics Today ◽  
2015 ◽  
Vol 68 (6) ◽  
pp. 18-19 ◽  
Author(s):  
Steven K. Blau
Keyword(s):  
Gravitational Lensing ◽  
Galaxy Cluster ◽  
The Galaxy

scholarly journals Revising the merger scenario of the galaxy cluster Abell 1644: a new gas poor structure discovered by weak gravitational lensing

2020 ◽  
Vol 495 (2) ◽  
pp. 2007-2021 ◽  
Author(s):  
R Monteiro-Oliveira ◽  
L Doubrawa ◽  
R E G Machado ◽  
G B Lima Neto ◽  
M Castejon ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Elliptical Galaxy ◽  
Galaxy Cluster ◽  
X Ray ◽  
The North ◽  
Density Maps ◽  
Hydrodynamical Simulation ◽  
The Galaxy ◽  
Maximum Separation ◽  
Comprehensive Study

ABSTRACT The galaxy cluster Abell 1644 ($\bar{z}=0.047$) is known for its remarkable spiral-like X-ray emission. It was previously identified as a bimodal system, comprising the subclusters, A1644S and A1644N, each one centred on a giant elliptical galaxy. In this work, we present a comprehensive study of this system, including new weak lensing and dynamical data and analysis plus a tailor-made hydrodynamical simulation. The lensing and galaxy density maps showed a structure in the North that could not be seen on the X-ray images. We, therefore, rename the previously known northern halo as A1644N1 and the new one as A1644N2. Our lensing data suggest that those have fairly similar masses: $M_{200}^{\rm N1}=0.90_{-0.85}^{+0.45} \times 10^{14}$ and $M_{200}^{\rm N2}=0.76_{-0.75}^{+0.37} \times 10^{14}$ M⊙, whereas the southern structure is the main one: $M_{200}^{\rm S}=1.90_{-1.28}^{+0.89}\times 10^{14}$ M⊙. Based on the simulations, fed by the observational data, we propose a scenario where the remarkable X-ray characteristics in the system are the result of a collision between A1644S and A1644N2 that happened ∼1.6 Gyr ago. Currently, those systems should be heading to a new encounter, after reaching their maximum separation.

scholarly journals Galaxies and clusters of galaxies as peak patches of the density field

2019 ◽  
Vol 490 (2) ◽  
pp. 1693-1696 ◽  
Author(s):  
Masataka Fukugita ◽  
Hans Böhringer
Keyword(s):  
Gravitational Lensing ◽  
Mass Density ◽  
Galaxy Cluster ◽  
Mass Range ◽  
Mass Function ◽  
Clusters Of Galaxies ◽  
Density Fraction ◽  
The Galaxy ◽  
Consistent Picture ◽  
Low Mass

ABSTRACT The mass function of galaxies and clusters of galaxies can be derived observationally based on different types of observations. In this study we test if these observations can be combined to a consistent picture which is also in accord with structure formation theory. The galaxy data comprise the optical galaxy luminosity function and the gravitational lensing signature of the galaxies, while the galaxy cluster mass function is derived from the X-ray luminosity distribution of the clusters. We show the results of the comparison in the form of the mass density fraction that is contained in collapsed objects relative to the mean matter density in the Universe. The mass density fraction in groups and clusters of galaxies extrapolated to low masses agrees very well with that of the galaxies: both converge at the low mass limit to a mass fraction of about 28 per cent if the outer radii of the objects are taken to be r200. Most of the matter contained in collapsed objects is found in the mass range $M_{200} \sim 10^{12}\!-\!10^{14}\, h^{-1}_{70} \, \mathrm{M}_\odot$, while a larger amount of the cosmic matter resides outside of r200 of collapsed objects.

Mass Discrepancy in the Galaxy Cluster RBS 864 Derived from X-rays and Gravitational Lensing

2006 ◽  
Vol 20 ◽  
pp. 281-282
Author(s):  
M. Gitti ◽  
W. Kausch ◽  
T. Erben ◽  
S. Schindler
Keyword(s):  
Gravitational Lensing ◽  
Galaxy Cluster ◽  
X Rays ◽  
The Galaxy

scholarly journals Tightening the constraints on the mass distribution of the Frontier Fields MACSJ0416.1-2403 with VLT/MUSE spectroscopy

2015 ◽  
Vol 11 (A29B) ◽  
pp. 781-782
Author(s):  
Benjamin Clément ◽  
Johan Richard ◽  
Guillaume Mahler ◽  
Vera Patrício ◽  
David Lagattuta ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Gravitational Lensing ◽  
Previous Analysis ◽  
Galaxy Cluster ◽  
Field Of View ◽  
Cluster Core ◽  
Large Field ◽  
Mass Model ◽  
Optical Wavelength ◽  
The Galaxy

AbstractWe have combined the performances of the VLT/MUSE spectrograph together with the power of gravitational lensing by Frontier Fields galaxy clusters to offer a unique magnified view of the distant universe. The large field of view over a wide optical wavelength domain enables redshift measurements of numerous lensed galaxies in the cluster core. Spectroscopically-confirmed multiple-imaged systems are further used as strong constraints to improve the cluster mass model. Here, we focus on the galaxy cluster MACSJ0416.1-2403 and compare the revised magnification map with results from previous analysis.

scholarly journals Gravitational Lensing Of Quasar 0957+561 And The Determination Of H0

1996 ◽  
Vol 173 ◽  
pp. 49-50 ◽  
Author(s):  
George Rhee ◽  
Gary Bernstein ◽  
Tony Tyson ◽  
Phil Fischer
Keyword(s):  
Gravitational Lensing ◽  
Galaxy Cluster ◽  
Cluster Center ◽  
Center Location ◽  
Multiple Imaging ◽  
Unique Model ◽  
The Galaxy

The double quasar 0957+561 was the first discovered instance of multiple imaging via gravitational lensing. The galaxy cluster is an important deflector as well as the first ranked galaxy. This has so far precluded construction of a unique model of the lens, reducing the accuracy of the derived H0 value. We have obtained deep images of the system at CFHT. The cluster is sufficiently massive to cause distortions on distant background galaxy images. We have used a mass map derived from lensing distortions to improve the accuracy of the cluster center location and place new limits on H0.

scholarly journals Scale dependence of galaxy biasing investigated by weak gravitational lensing: An assessment using semi-analytic galaxies and simulated lensing data

2018 ◽  
Vol 613 ◽  
pp. A15 ◽  
Author(s):  
Patrick Simon ◽  
Stefan Hilbert
Keyword(s):  
Gravitational Lensing ◽  
Spatial Scales ◽  
Scale Dependence ◽  
Reconstruction Technique ◽  
Weak Gravitational Lensing ◽  
Physical Scale ◽  
The Galaxy ◽  
Galaxy Bias ◽  
The Impact ◽  
Lens Galaxies

Galaxies are biased tracers of the matter density on cosmological scales. For future tests of galaxy models, we refine and assess a method to measure galaxy biasing as a function of physical scalekwith weak gravitational lensing. This method enables us to reconstruct the galaxy bias factorb(k) as well as the galaxy-matter correlationr(k) on spatial scales between 0.01hMpc−1≲k≲ 10hMpc−1for redshift-binned lens galaxies below redshiftz≲ 0.6. In the refinement, we account for an intrinsic alignment of source ellipticities, and we correct for the magnification bias of the lens galaxies, relevant for the galaxy-galaxy lensing signal, to improve the accuracy of the reconstructedr(k). For simulated data, the reconstructions achieve an accuracy of 3–7% (68% confidence level) over the abovek-range for a survey area and a typical depth of contemporary ground-based surveys. Realistically the accuracy is, however, probably reduced to about 10–15%, mainly by systematic uncertainties in the assumed intrinsic source alignment, the fiducial cosmology, and the redshift distributions of lens and source galaxies (in that order). Furthermore, our reconstruction technique employs physical templates forb(k) andr(k) that elucidate the impact of central galaxies and the halo-occupation statistics of satellite galaxies on the scale-dependence of galaxy bias, which we discuss in the paper. In a first demonstration, we apply this method to previous measurements in the Garching-Bonn Deep Survey and give a physical interpretation of the lens population.

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

scholarly journals DeepChandraobservation of the galaxy cluster WARPJ1415.1+3612 atz=1

2012 ◽  
Vol 539 ◽  
pp. A105 ◽  
Author(s):  
J. S. Santos ◽  
P. Tozzi ◽  
P. Rosati ◽  
M. Nonino ◽  
G. Giovannini
Keyword(s):  
Galaxy Cluster ◽  
The Galaxy

scholarly journals Anisotropy of the galaxy cluster X-ray luminosity–temperature relation

2018 ◽  
Vol 611 ◽  
pp. A50 ◽  
Author(s):  
Konstantinos Migkas ◽  
Thomas H. Reiprich
Keyword(s):  
Galaxy Clusters ◽  
Statistical Significance ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
Luminosity Distance ◽  
Temperature Relation ◽  
X Ray ◽  
Two Samples ◽  
The Galaxy ◽  
Group A

We introduce a new test to study the cosmological principle with galaxy clusters. Galaxy clusters exhibit a tight correlation between the luminosity and temperature of the X-ray-emitting intracluster medium. While the luminosity measurement depends on cosmological parameters through the luminosity distance, the temperature determination is cosmology-independent. We exploit this property to test the isotropy of the luminosity distance over the full extragalactic sky, through the normalization a of the LX–T scaling relation and the cosmological parameters Ωm and H0. To this end, we use two almost independent galaxy cluster samples: the ASCA Cluster Catalog (ACC) and the XMM Cluster Survey (XCS-DR1). Interestingly enough, these two samples appear to have the same pattern for a with respect to the Galactic longitude. More specifically, we identify one sky region within l ~ (−15°, 90°) (Group A) that shares very different best-fit values for the normalization of the LX–T relation for both ACC and XCS-DR1 samples. We use the Bootstrap and Jackknife methods to assess the statistical significance of these results. We find the deviation of Group A, compared to the rest of the sky in terms of a, to be ~2.7σ for ACC and ~3.1σ for XCS-DR1. This tension is not significantly relieved after excluding possible outliers and is not attributed to different redshift (z), temperature (T), or distributions of observable uncertainties. Moreover, a redshift conversion to the cosmic microwave background (CMB) frame does not have an important impact on our results. Using also the HIFLUGCS sample, we show that a possible excess of cool-core clusters in this region, is not able to explain the obtained deviations. Furthermore, we tested for a dependence of the results on supercluster environment, where the fraction of disturbed clusters might be enhanced, possibly affecting the LX–T relation. We indeed find a trend in the XCS-DR1 sample for supercluster members to be underluminous compared to field clusters. However, the fraction of supercluster members is similar in the different sky regions, so this cannot explain the observed differences, either. Constraining Ωm and H0 via the redshift evolution of LX–T and the luminosity distance via the flux–luminosity conversion, we obtain approximately the same deviation amplitudes as for a. It is interesting that the general observed behavior of Ωm for the sky regions that coincide with the CMB dipole is similar to what was found with other cosmological probes such as supernovae Ia. The reason for this behavior remains to be identified.

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