632 research outputs found
On mass and shape of galaxy clusters by comparison of X-ray, Sunyaev-Zel'dovich effect, and gravitational lensing observations
No full textThe accurate determination of the mass of galaxy clusters is crucial to precision astronomy. We have often to deal with either biased measurements or precise determinations of peculiar quantities. A better understanding of intrinsic shapes plays a major role. We consider how the shape of the intracluster medium (ICM) can be inferred by combining X-ray photometry and spectroscopy with the measurement of the Sunyaev-Zel'dovich effect (SZe). Together with gravitational lensing (GL), we can get unbiased estimates of mass and concentration and probe the hydrodynamical properties of the cluster
Mass, shape and thermal properties of Abell 1689 using a multiwavelength X-ray, lensing and Sunyaev-Zel'dovich analysis
No full textKnowledge of the mass and concentration of galaxy clusters is crucial for an understanding of their formation and evolution. Unbiased estimates require an understanding of the shape and orientation of the halo as well as its equilibrium status. We propose a novel method to determine the intrinsic properties of galaxy clusters from a multiwavelength data set, spanning from X-ray spectroscopic and photometric data to gravitational lensing to the Sunyaev-Zel'dovich effect. The method relies on two non-informative geometrical assumptions: the distributions of total matter or gas are approximately ellipsoidal and co-aligned; they have different, constant axial ratios but share the same degree of triaxiality. Weak and strong lensing probe the features of the total mass distribution in the plane of the sky. X-ray data measure the size and orientation of the gas in the plane of the sky. Comparison with the Sunyaev-Zel'dovich amplitude fixes the elongation of the gas along the line of sight. These constraints are deprojected as a result of Bayesian inference. The mass distribution is described as a Navarro-Frenk-White halo with arbitrary orientation, and the gas density and temperature are modelled with parametric profiles. We have applied the method to Abell 1689. Independently of the priors, the cluster is massive, M-200 = (1.3 +/- 0.2) x 10(15) M circle dot, and overconcentrated, c(200) = 8 +/- 1, but it is still consistent with theoretical predictions. The total matter is triaxial (minor to major axial ratio similar to 0.5 +/- 0.1, exploiting priors from N-body simulations) with the major axis nearly orientated along the line of sight. The gas is rounder (minor to major axial ratio similar to 0.6 +/- 0.1) and deviates from hydrostatic equilibrium. The contribution of non-thermal pressure is similar to 20-50 per cent in the inner regions, less than or similar to 300 kpc, and similar to 25 +/- 5 per cent at similar to 1.5 Mpc. This picture of A1689 was obtained with a small number of assumptions and in a single framework, suitable for application to a large variety of clusters
Testing Strict Hydrostatic Equilibrium in Simulated Clusters of Galaxies: Implications for A1689
No full textThree-dimensional structure of the complex between calmodulin mutant lacking the c-terminal five residues and the calmodulin-binding peptide derived from skeletal muscle myosin light-chain kinase
No full textIn our previous study, functional ability and conformational stability had been examined for C-terminal deletion mutants of a 148-residue Ca2+-binding protein, chicken calmodulin (CaM). In that study, we had reported that a mutant named CCMΔ5, missing five residues at the C-terminus, activates CaM-target as much as full-length CaM does. This finding is intriguing because CCMΔ5 lacks the key residues, Met144 and Met145, for the target activation. To uncover why CCMΔ5 displays proper function, here we report the three-dimensional structure of CCMΔ5 bound to the peptide derived from skeletal muscle myosin light-chain kinase (skMLCK). The structure determination was achieved using multidimensional nuclear magnetic resonance (NMR) spectroscopy. The complex structure of CCM∆5-skMLCK was compared to that of wild CaM-skMLCK. The results showed that the orientation of helix-1 and helix-5 in CCM∆5 differs from those in wild CaM. Moreover, distinctive hydrophobic interaction manner was found in the binding between CCM∆5 and peptide; Phe141, Ala128, Met109, Leu105 and Phe92 of CCM∆5 contribute to the interaction with Trp4 of the skMLCK peptide. Abbreviations: CaM, calmodulin; CCMΔX, a deletion mutant of CaM that lacks X C-terminal residues; NMR, Nuclear magnetic resonance; PDB, Protein date bank; skMLCK, skeletal muscle myosin light-chain kinase; TOF-MS, Time-of-flight mass spectrometry; RMSD, root mean square deviation; SDS-PAGE, Sodium dodecyl sulfate polyacrylamide gel electrophoresis Citation: Vu Van Dung, Umetsu Y., Ohki S., 2017. Three-dimensional structure of the complex between calmodulin mutant lacking the c-terminal five residues and the calmodulin-binding peptide derived from skeletal muscle myosin light-chain kinase. Tap chi Sinh hoc, 39(3): 309-319. DOI: 10.15625/0866-7160/v39n3.10111. *Corresponding author: [email protected] Received 19 June 2017, accepted 20 August 2017 </jats:p
Cluster Lensing Mass Inversion (CLUMI+): Combining Dynamics and Weak Lensing around Galaxy Clusters
No full textWe present clumi+ , a self-consistent, multiprobe methodology for reconstructing the mass distribution in and around galaxy clusters by combining gravitational lensing and dynamical observations. Building on the joint likelihood framework of K. Umetsu, clumi+ integrates weak-lensing shear and magnification data with projected escape velocity measurements in the cluster infall region, yielding tighter constraints on the gravitational potential without relying on equilibrium assumptions. The mass distribution is modeled using a flexible, piecewise-defined convergence profile that characterizes the azimuthally averaged surface mass density within the lensing field, transitioning to a projected power-law form at larger radii where phase-space constraints complement lensing. Additional strong-lensing constraints are incorporated via central aperture-mass measurements, enabling full-scale mass reconstruction from the cluster core to the outskirts. We validate clumi+ using synthetic weak-lensing and phase-space data for a massive cluster from the IllustrisTNG simulations, demonstrating unbiased recovery of projected and three-dimensional mass profiles and achieving 10%–30% improvement in precision at large radii. As a case study, we apply clumi+ to A2261, combining Subaru and Hubble Space Telescope weak+strong-lensing data with spectroscopic measurements from the Hectospec Cluster Survey. This analysis demonstrates the power of multiprobe, equilibrium-free modeling for robust cluster mass reconstruction
CLASH-VLT:a full dynamical reconstruction of the mass profile of Abell S1063 from 1 kpc out to the virial radius
Get PDFContext. The shape of the mass density profiles of cosmological halos informs us of the nature of dark matter (DM) and DM-baryons interactions. Previous estimates of the inner slope of the mass density profiles of clusters of galaxies are in opposition to predictions derived from numerical simulations of cold dark matter (CDM).
Aims. We determine the inner slope of the DM density profile of a massive cluster of galaxies, Abell S1063 (RXC J2248.7−4431) at z = 0.35, with a dynamical analysis based on an extensive spectroscopic campaign carried out with the VIMOS and MUSE spectrographs at the ESO VLT. This new data set provides an unprecedented sample of 1234 spectroscopic members, 104 of which are located in the cluster core (R ≲ 200 kpc), extracted from the MUSE integral field spectroscopy. The latter also allows the stellar velocity dispersion profile of the brightest cluster galaxy (BCG) to be measured out to 40 kpc.
Methods. We used an upgraded version of the MAMPOSSt technique to perform a joint maximum likelihood fit to the velocity dispersion profile of the BCG and to the velocity distribution of cluster member galaxies over a radial range from 1 kpc to the virial radius (r200 ≈ 2.7 Mpc).
Results. We find a value of γDM = 0.99 ± 0.04 for the inner logarithmic slope of the DM density profile after marginalizing over all the other parameters of the mass and velocity anisotropy models. Moreover, the newly determined dynamical mass profile is found to be in excellent agreement with the mass density profiles obtained from the independent X-ray hydrostatic analysis based on deep Chandra data, as well as the strong and weak lensing analyses.
Conclusions. Our value of the inner logarithmic slope of the DM density profile γDM is in very good agreement with predictions from cosmological CDM simulations. We will extend our analysis to more clusters in future works. If confirmed on a larger cluster sample, our result makes this DM model more appealing than alternative models
Corticosteroids Inhibit Il-12 Production In Human Monocytes And Enhance Their Capacity To Induce Il-4 Synthesis In Cd4+ Lymphocytes
No full textWe examined the effects of corticosteroids on IL-12 production by human monocytes and on cytokine synthesis in T cells. To distinguish the effects of corticosteroids on the APC used to activate the T cell from direct effects of corticosteroids on the T cell, experiments were performed by exposing the APC and not the T cell to corticosteroids. We found that corticosteroids significantly inhibited the production in monocytes of IL-12, a cytokine that is extremely potent in enhancing IFN-γ and inhibiting IL-4 synthesis in T cells. We demonstrated that reduced production of IL-12 in corticosteroid-treated monocytes resulted in a decreased capacity of the monocytes to induce IFN-γ and an increased ability to induce IL-4 in T cells. 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Dark matter fraction of low-mass cluster members probed by galaxy-scale strong lensing
No full textWe present a strong lensing system composed of four multiple images ofa source at z = 2.387 created by two lens galaxies G1 and G2belonging to the galaxy cluster MACS J1115.9+0129 at z = 0.353. We useobservations taken as part of the Cluster Lensing and Supernova surveywith Hubble and its spectroscopic follow-up programme at the Very LargeTelescope to estimate the total mass distributions of the two galaxiesand the cluster through strong gravitational lensing models. We findthat the total projected mass values within the half-light radiiR_e of the two lens galaxies areM_TG1(<R_e G1) = (3.6 ± 0.4) ×10^10 M_⊙ and M_TG2(<R_eG2) = (4.2 ± 1.6) × 10^10M_⊙. The effective velocity dispersion values of G1 and G2are (122 ± 7) km s^-1 and (137 ± 27) kms^-1 respectively. We remark that these values are relativelylow when compared to those of ≈200-300 km s^-1 typical oflens galaxies found in the field by previous surveys. By fitting thespectral energy distributions of G1 and G2 we measure projectedluminous over total mass fractions within R_e of 0.11 ±0.03 for G1 and 0.73 ± 0.32 for G2. The fact that the lessmassive galaxy G1 is dark matter-dominated in its inner regions raisesthe question of whether the dark matter fraction in the core ofearly-type galaxies depends on their mass. Further investigating stronglensing systems will help us understand the influence that dark matterhas on the structure and evolution of the inner regions of galaxies
CLASH-VLT: constraints on f(R) gravity models with galaxy clusters using lensing and kinematic analyses
No full textWe perform a maximum likelihood kinematic analysis of the two dynamically relaxed galaxy clusters MACS J1206.2-0847 at z = 0.44 and RXC J2248.7-4431 at z = 0.35 to determine the total mass profile in modified gravity models, using a modified version of the MAMPOSSt code of Mamon, Biviano and Boue. Our work is based on the kinematic and lensing mass profiles derived using the data from the Cluster Lensing And Supernova survey with Hubble (hereafter CLASH) and the spectroscopic follow-up with the Very Large Telescope (hereafter CLASH-VLT). We assume a spherical Navarro-Frenk-White (NFW hereafter) profile in order to obtain a constraint on the fifth force interaction range lambda for models in which the dependence of this parameter on the environment is negligible at the scale considered (i.e. lambda = const) and fixing the fifth force strength to the value predicted in f(R) gravity. We then use information from lensing analysis to put a prior on the other NFW free parameters. In the case of MACSJ 1206 the joint kinematic+lensing analysis leads to an upper limit on the effective interaction range lambda = 0.14 Mpc at Delta chi(2) = 2.71. This is consequence of the slight difference between the lensing and kinematic data, appearing in GR for this cluster, that could in principle be explained in terms of modifications of gravity. We discuss the impact of systematics and the limits of our analysis as well as future improvements of the results obtained. This work has interesting implications in view of upcoming and future large imaging and spectroscopic surveys, that will deliver lensing and kinematic mass reconstruction for a large number of galaxy clusters
The Concentration-Mass Relation from CLASH clusters using galaxy dynamics
No full textGalaxy clusters play a key role in testing cosmological models and in constraining the properties of dark matter. One of these key tests is the mass density profile of clusters - the concentration-mass relation. There is a reported tension between the observed concentration-mass relation and the one theoretically expected using simulated galaxy clusters, where the observed clusters appear to have higher concentration than simulated clusters of similar total mass. In The Cluster Lensing And Supernova survey with Hubble (CLASH), we use different and independent techniques to estimate the mass distribution in clusters. The comparison between different techniques offers an observational test of the techniques and understanding of the systematics. In this work, we estimate the concentration-mass relation for about 8 (at the 0.2< z &;lt; 0.6 redshift range) of the 20 X-ray selected CLASH clusters using galaxy dynamics. We use a unique spectroscopic data set with more than about 300 cluster members per cluster. Finally, we compare our results to the theoretical expected ones and to the estimations derived using the lensing technique
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