scholarly journals AStroLens: automatic strong-lens modelling of X-ray selected galaxy clusters

2020 ◽  
Vol 498 (1) ◽  
pp. 1121-1139
Author(s):  
Lukas Zalesky ◽  
Harald Ebeling
Keyword(s):  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Gravitational Lens ◽  
X Ray ◽  
Cluster Galaxies ◽  
The Public ◽  
Optical Images ◽  
Strong Lensing ◽  
Massive Cluster ◽  
Good Agreement

ABSTRACT We use AStroLens, a newly developed gravitational lens-modelling code that relies only on geometric and photometric information of cluster galaxies as input, to map the strong-lensing regions and estimate the lensing strength of 96 galaxy clusters at z = 0.5–0.9. All clusters were identified during the extended Massive Cluster Survey (eMACS) based on their X-ray flux and optical appearance. Building on the well-tested assumption that the distribution of both luminous and dark matter in galaxy clusters is approximately traced by the distribution of light, i.e. that light traces mass, AStroLens uses three global parameters to automatically model the deflection from strong-gravitational lensing for all galaxy clusters in this diverse sample. We test the robustness of our code by comparing AStroLens estimates derived solely from shallow optical images in two passbands with the results of in-depth lens-modelling efforts for two well-studied eMACS clusters and find good agreement, both with respect to the size and the shape of the strong-lensing regime delineated by the respective critical lines. Our study finds 31 eMACS clusters with effective Einstein radii (θE) in excess of 20″ and eight with θE > 30″, thereby underlining the value of X-ray selection for the discovery of powerful cluster lenses that complement giants like MACSJ0717 at ever-increasing redshift. As a first installment towards the public release of the eMACS sample, we list physical properties of the 10 calibration clusters as well as of the 10 most powerful eMACS cluster lenses, according to AStroLens.

scholarly journals Constraints on Dark Energy Models from Selected Galaxy Clusters (S-Z + X-Ray Data) and Gravitational Lensing Data

2016 ◽  
Author(s):  
Alexander Bonilla Rivera ◽  
Jairo Ernesto Castillo Hernandez
Keyword(s):  
Dark Energy ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Information Criterion ◽  
Gravitational Lens ◽  
X Rays ◽  
Hot Electron ◽  
X Ray ◽  
Angular Diameter Distance ◽  
Energy Models

The Sunyaev-Zeldovich effect (SZe) is a global distortion of Cosmic Microwave Bckground (CMB) spectrum as result of its interaction with a hot electron plasma in the intracluster medium for large gravitational virialized structures such as galaxy clusters. Furthermore, this hot gas of electrons emits X-Rays due to its fall in the gravitational potential well of the cluster. The analysis of SZe and X-Ray data, provide a method for calculating distances to galaxy clusters at any redshift (Angular diameter distance (dA) and gas mass fraction (fgas)). On the other side, many of these galaxy clusters produce a Strong Gravitational Lens effect (SGL), which has become an useful astrophysical tool for cosmology. We use these cosmological tests, in addition to the more traditional ones (SNIa, CMB, BAO), to constraint alternative models of dark energy (ωCDM, CPL, IDE, EDE) and study the history of expansion through the cosmographic parameters (H(z), q(z), j(z)). Using Akaike and Bayesian Information Criterion (AIC, BIC) we find that the ωCDM and ΛCDM models are the most favored by the observational data. In addition, we found that at low redshift appears an peculiar behavior of slowdown of aceleration, which occurs only on dynamical dark energy models using only galaxy clusters (dA,clusters + fgas).

scholarly journals Observable tests of self-interacting dark matter in galaxy clusters: cosmological simulations with SIDM and baryons

2019 ◽  
Vol 488 (3) ◽  
pp. 3646-3662 ◽  
Author(s):  
Andrew Robertson ◽  
David Harvey ◽  
Richard Massey ◽  
Vincent Eke ◽  
Ian G McCarthy ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Interaction Strength ◽  
Matter Distribution ◽  
Cosmological Simulations ◽  
X Ray ◽  
Critical Curves ◽  
Strong Lensing ◽  
Dark Matter Distribution

ABSTRACT We present bahamas-SIDM, the first large-volume, $(400 \, h^{-1} \mathrm{\, Mpc})^{3}$, cosmological simulations including both self-interacting dark matter (SIDM) and baryonic physics. These simulations are important for two primary reasons: (1) they include the effects of baryons on the dark matter distribution and (2) the baryon particles can be used to make mock observables that can be compared directly with observations. As is well known, SIDM haloes are systematically less dense in their centres, and rounder, than CDM haloes. Here, we find that that these changes are not reflected in the distribution of gas or stars within galaxy clusters, or in their X-ray luminosities. However, gravitational lensing observables can discriminate between DM models, and we present a menu of tests that future surveys could use to measure the SIDM interaction strength. We ray-trace our simulated galaxy clusters to produce strong lensing maps. Including baryons boosts the lensing strength of clusters that produce no critical curves in SIDM-only simulations. Comparing the Einstein radii of our simulated clusters with those observed in the CLASH survey, we find that at velocities around $1000 \mathrm{\, km \, s^{-1}}$ an SIDM cross-section of $\sigma /m \gtrsim 1 \, \mathrm{cm^2 \, g^{-1}}$ is likely incompatible with observed cluster lensing.

scholarly journals Constraints on Dark Energy Models from Selected Galaxy Clusters (S-Z + X-Ray Data) and Gravitational Lensing Data

2016 ◽  
Author(s):  
Alexander Bonilla Rivera ◽  
Jairo Ernesto Castillo Hernandez
Keyword(s):  
Dark Energy ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Information Criterion ◽  
Gravitational Lens ◽  
X Rays ◽  
Hot Electron ◽  
X Ray ◽  
Angular Diameter Distance ◽  
Energy Models

The Sunyaev-Zeldovich effect (SZe) is a global distortion of Cosmic Microwave Bckground (CMB) spectrum as result of its interaction with a hot electron plasma in the intracluster medium for large gravitational virialized structures such as galaxy clusters. Furthermore, this hot gas of electrons emits X-Rays due to its fall in the gravitational potential well of the cluster. The analysis of SZe and X-Ray data, provide a method for calculating distances to galaxy clusters at any redshift (Angular diameter distance (dA) and gas mass fraction (fgas)). On the other side, many of these galaxy clusters produce a Strong Gravitational Lens effect (SGL), which has become an useful astrophysical tool for cosmology. We use these cosmological tests, in addition to the more traditional ones (SNIa, CMB, BAO), to constraint alternative models of dark energy (ωCDM, CPL, IDE, EDE) and study the history of expansion through the cosmographic parameters (H(z), q(z), j(z)). Using Akaike and Bayesian Information Criterion (AIC, BIC) we find that the ωCDM and ΛCDM models are the most favored by the observational data. In addition, we found that at low redshift appears an peculiar behavior of slowdown of aceleration, which occurs only on dynamical dark energy models using only galaxy clusters (dA,clusters + fgas).

The AGN dependence on cluster mass

2018 ◽  
Vol 14 (S342) ◽  
pp. 145-148
Author(s):  
Elias Koulouridis ◽  
Keyword(s):  
Galaxy Clusters ◽  
High Velocity ◽  
High Redshift ◽  
High Mass ◽  
X Ray ◽  
Cluster Galaxies ◽  
Cluster Mass ◽  
Bona Fide ◽  
Low Mass ◽  
Velocity Dispersions

AbstractWe present the results of a study of the AGN density in a homogeneous and well studied sample of 167 bona-fide X-ray galaxy clusters (0.1<z<0.5). Our aim is to study the AGN activity in 167 XXL X-ray galaxy clusters as a function of the cluster mass and the location of the AGN in the cluster. We report a significant AGN excess in our low-mass cluster sub-sample between 0.5r500 and 2r500. In contrast, the high-mass sub-sample presents no AGN excess. The AGN excess in poor clusters indicates AGN triggering, supporting previous studies that reported enhanced galaxy merging in the cluster outskirts. This effect is probably prevented by high velocity dispersions in high-mass clusters. Comparing also with previous studies of massive or high-redshift clusters, we conclude that the AGN fraction in cluster galaxies anti-correlates strongly with cluster mass.

scholarly journals Applying MOG to Lensing: Einstein Rings, Abell 520 and the Bullet Cluster

Galaxies ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 43 ◽  
Author(s):  
John Moffat ◽  
Sohrab Rahvar ◽  
Viktor Toth
Keyword(s):  
Gravitational Lensing ◽  
Equations Of Motion ◽  
Astronomical Observations ◽  
Test Particles ◽  
Strong Lensing ◽  
Modified Theory Of Gravity ◽  
Small Set ◽  
Modified Theory ◽  
Bending Of Light ◽  
Good Agreement

We investigate gravitational lensing in the context of the MOG modified theory of gravity. Using a formulation of the theory with no adjustable or fitted parameters, we present the MOG equations of motion for slow, nonrelativistic test particles and for ultrarelativistic test particles, such as rays of light. We demonstrate how the MOG prediction for the bending of light can be applied to astronomical observations. Our investigation first focuses on a small set of strong lensing observations where the properties of the lensing objects are found to be consistent with the predictions of the theory. We also present an analysis of the colliding clusters 1E0657-558 (known also as the Bullet Cluster) and Abell 520; in both cases, the predictions of the MOG theory are in good agreement with observation.

scholarly journals New observational constraints on interacting dark energy using galaxy clusters virial equilibrium states

2019 ◽  
Vol 490 (2) ◽  
pp. 1944-1952
Author(s):  
M Le Delliou ◽  
R J F Marcondes ◽  
G B Lima Neto
Keyword(s):  
Dark Energy ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Coupling Parameter ◽  
Interaction Strength ◽  
Dynamical Evolution ◽  
Optical Observations ◽  
Dark Sector ◽  
X Ray ◽  
Tightly Coupled

ABSTRACT The nature of the dark sector components of the Universe still remains one of the largest unknown. Among many possibilities, it has been speculated that dark matter and dark energy may be more tightly coupled than usually thought, one component interacting with the other. Here, we continue to explore the possible dark sector interaction through means of the Layzer–Irvine equation together with a model of an interacting dark sector applied to clusters of galaxies. We have selected galaxy clusters that have their mass profiles determined by gravitational lensing effect (optical observations) and have their intracluster gas temperatures measured from X-ray observations and spectral fit found in the literature. Using a simple model based on semi-analytical simulations, we derived a putative dynamical evolution of the clusters and used it to estimate the coupling parameter of the dark sector interaction. Through a Bayesian analysis, we obtain a 3σ detection of the interaction strength for 11 clusters at −0.027 ± 0.009 that translates in a compounded Universal equilibrium virial ratio, U/T, of $-0.61^{+0.04}_{-0.03}$. We note that the X-ray temperature determination is sometimes inconsistent, depending on the instrument and/or methodology used. The level of detection and these inconsistencies call for caution. We expect that future observations will give us a clearer indication of an eventual dark sector interaction.

scholarly journals Shapes and alignments of dark matter haloes and their brightest cluster galaxies in 39 strong lensing clusters

2020 ◽  
Vol 496 (3) ◽  
pp. 2591-2604 ◽  
Author(s):  
Taizo Okabe ◽  
Masamune Oguri ◽  
Sébastien Peirani ◽  
Yasushi Suto ◽  
Yohan Dubois ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Hubble Space Telescope ◽  
Mean Value ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Strong Lensing ◽  
The Mean ◽  
The Difference ◽  
Massive Clusters

ABSTRACT We study shapes and alignments of 45 dark matter (DM) haloes and their brightest cluster galaxies (BCGs) using a sample of 39 massive clusters from Hubble Frontier Field (HFF), Cluster Lensing And Supernova survey with Hubble (CLASH), and Reionization Lensing Cluster Survey (RELICS). We measure shapes of the DM haloes by strong gravitational lensing, whereas BCG shapes are derived from their light profiles in Hubble Space Telescope images. Our measurements from a large sample of massive clusters presented here provide new constraints on DM and cluster astrophysics. We find that DM haloes are on average highly elongated with the mean ellipticity of 0.482 ± 0.028, and position angles of major axes of DM haloes and their BCGs tend to be aligned well with the mean value of alignment angles of 22.2 ± 3.9 deg. We find that DM haloes in our sample are on average more elongated than their BCGs with the mean difference of their ellipticities of 0.11 ± 0.03. In contrast, the Horizon-AGN cosmological hydrodynamical simulation predicts on average similar ellipticities between DM haloes and their central galaxies. While such a difference between the observations and the simulation may well be explained by the difference of their halo mass scales, other possibilities include the bias inherent to strong lensing measurements, limited knowledge of baryon physics, or a limitation of cold DM.

scholarly journals Reconstruction of the two-dimensional gravitational potential of galaxy clusters from X-ray and Sunyaev-Zel’dovich measurements

2018 ◽  
Vol 614 ◽  
pp. A38 ◽  
Author(s):  
C. Tchernin ◽  
M. Bartelmann ◽  
K. Huber ◽  
A. Dekel ◽  
G. Hurier ◽  
...  
Keyword(s):  
Covariance Matrix ◽  
Galaxy Clusters ◽  
Gravitational Potential ◽  
Gravitational Lensing ◽  
Simulated Data ◽  
Forthcoming Paper ◽  
X Rays ◽  
Two Dimensional ◽  
X Ray ◽  
Joint Reconstruction

Context. The mass of galaxy clusters is not a direct observable, nonetheless it is commonly used to probe cosmological models. Based on the combination of all main cluster observables, that is, the X-ray emission, the thermal Sunyaev–Zel’dovich (SZ) signal, the velocity dispersion of the cluster galaxies, and gravitational lensing, the gravitational potential of galaxy clusters can be jointly reconstructed. Aims. We derive the two main ingredients required for this joint reconstruction: the potentials individually reconstructed from the observables and their covariance matrices, which act as a weight in the joint reconstruction. We show here the method to derive these quantities. The result of the joint reconstruction applied to a real cluster will be discussed in a forthcoming paper. Methods. We apply the Richardson-Lucy deprojection algorithm to data on a two-dimensional (2D) grid. We first test the 2D deprojection algorithm on a β-profile. Assuming hydrostatic equilibrium, we further reconstruct the gravitational potential of a simulated galaxy cluster based on synthetic SZ and X-ray data. We then reconstruct the projected gravitational potential of the massive and dynamically active cluster Abell 2142, based on the X-ray observations collected with XMM-Newton and the SZ observations from the Planck satellite. Finally, we compute the covariance matrix of the projected reconstructed potential of the cluster Abell 2142 based on the X-ray measurements collected with XMM-Newton. Results. The gravitational potentials of the simulated cluster recovered from synthetic X-ray and SZ data are consistent, even though the potential reconstructed from X-rays shows larger deviations from the true potential. Regarding Abell 2142, the projected gravitational cluster potentials recovered from SZ and X-ray data reproduce well the projected potential inferred from gravitational-lensing observations. We also observe that the covariance matrix of the potential for Abell 2142 reconstructed from XMM-Newton data sensitively depends on the resolution of the deprojected grid and on the smoothing scale used in the deprojection. Conclusions. We show that the Richardson-Lucy deprojection method can be effectively applied on a grid and that the projected potential is well recovered from real and simulated data based on X-ray and SZ signal. The comparison between the reconstructed potentials from the different observables provides additional information on the validity of the assumptions as function of the projected radius.

scholarly journals The impact of disturbed galaxy clusters on the kinematics of active galactic nuclei

2020 ◽  
Vol 499 (3) ◽  
pp. 3792-3805
Author(s):  
Lawrence E Bilton ◽  
Kevin A Pimbblet ◽  
Yjan A Gordon
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Cluster Galaxies ◽  
Sky Survey ◽  
The Impact

ABSTRACT We produce a kinematic analysis of AGN-hosting cluster galaxies from a sample of 33 galaxy clusters selected using the X-ray Clusters Database (BAX) and populated with galaxies from the Sloan Digital Sky Survey Data Release 8. The 33 galaxy clusters are delimited by their relative intensity of member galaxy substructuring as a proxy to core merging to derive two smaller sub-samples of 8 dynamically active (merging) and 25 dynamically relaxed (non-merging) states. The AGN were selected for each cluster sub-sample by employing the WHAN diagram to the strict criteria of log10([N ii]/Hα) ≥ −0.32 and EWHα ≥ 6 Å, providing pools of 70 mergings and 225 non-merging AGN sub-populations. By co-adding the clusters to their respective dynamical states to improve the signal-to-noise ratio of our AGN sub-populations we find that merging galaxy clusters on average host kinematically active AGN between 0–1.5r200 as r200 → 0, where their velocity dispersion profile (VDP) presents a significant deviation from the non-AGN sub-population VDP by ≳3σ. This result is indicative that the AGN-hosting cluster galaxies have recently coalesced on to a common potential. Further analysis of the composite distributions illustrates non-merging AGN-hosting sub-populations have, on average, already been accreted and predominantly lie within backsplash regions of the projected phase-space. This suggests merging cluster dynamical states hold relatively younger AGN sub-populations kinematically compared with those found in non-merging cluster dynamical states.

scholarly journals Spectroscopic Evidences for Star Formation in Cooling Flow Galaxies

1996 ◽  
Vol 171 ◽  
pp. 349-349
Author(s):  
N. Cardiel ◽  
J. Gorgas ◽  
A. Aragon-Salamanca
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
X Ray ◽  
Cluster Galaxies ◽  
Cooling Flows ◽  
Cooling Flow ◽  
Brightest Cluster Galaxies

X-ray observations have led to the conclusion that many galaxy clusters are hosting cooling flows. The brightest cluster galaxies could have accreted masses of the order of 1011–1012M⊙, but is still uncertain what the final fate of the accreted gas may be.

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