Systematic Perturbations of the Thermodynamic Properties in Cool Cores of HIFLUGCS Galaxy Clusters

Abstract We present an ensemble X-ray analysis of systematic perturbations in the central hot gas properties for a sample of 28 nearby strong cool-core systems, selected from the HIghest X-ray FLUx Galaxy Cluster Sample (HIFLUGCS). We analyze their cool-core features observed with the Chandra X-ray Observatory. All individual systems in our sample exhibit at least a pair of positive and negative excess perturbations in the X-ray residual image after subtracting the global brightness profile. We extract and analyze X-ray spectra of the intracluster medium (ICM) in the detected perturbed regions. To investigate possible origins of the gas perturbations, we characterize thermodynamic properties of the ICM in the perturbed regions and characterize their correlations between positive and negative excess regions. The best-fit relations for temperature and entropy show a clear offset from the one-to-one relation, T neg / T pos = 1.20 − 0.03 + 0.04 and K neg/K pos = 1.43 ± 0.07, whereas the best-fit relation for pressure is found to be remarkably consistent with the one-to-one relation P neg = P pos, indicating that the ICM in the perturbed regions is in pressure equilibrium. These observed features in the HIFLUGCS sample are in agreement with the hypothesis that the gas perturbations in cool cores are generated by gas sloshing. We also analyze synthetic observations of perturbed cluster cores created from binary merger simulations, finding that the observed temperature ratio agrees with the simulations, T neg/T pos ∼ 1.3. We conclude that gas sloshing induced by infalling substructures plays a major role in producing the characteristic gas perturbations in cool cores. The ubiquitous presence of gas perturbations in cool cores may suggest a significant contribution of gas sloshing to suppressing runaway cooling of the ICM.

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Unbinding of Hyaluronan Accelerates the Enzymatic Activity of Bee Hyaluronidase

Journal of Biological Chemistry ◽

10.1074/jbc.m111.263731 ◽

2011 ◽

Vol 286 (41) ◽

pp. 35699-35707 ◽

Cited By ~ 2

Author(s):

Attila Iliás ◽

Károly Liliom ◽

Brigitte Greiderer-Kleinlercher ◽

Stephan Reitinger ◽

Günter Lepperdinger

Keyword(s):

Experimental Data ◽

Quartz Crystal ◽

Surface Loop ◽

X Ray ◽

Site Model ◽

Substrate Interaction ◽

Close Proximity ◽

Binding Groove ◽

The One ◽

Best Fit

Hyaluronan (HA), a polymeric glycosaminoglycan ubiquitously present in higher animals, is hydrolyzed by hyaluronidases (HAases). Here, we used bee HAase as a model enzyme to study the HA-HAase interaction. Located in close proximity to the active center, a bulky surface loop, which appears to obstruct one end of the substrate binding groove, was found to be functionally involved in HA turnover. To better understand kinetic changes in substrate interaction, binding of high molecular weight HA to catalytically inactive HAase was monitored by means of quartz crystal microbalance technology. Replacement of the delimiting loop by a tetrapeptide interconnection increased the affinity for HA up to 100-fold, with a KD below 1 nm being the highest affinity among HA-binding proteins surveyed so far. The experimental data of HA-HAase interaction were further validated showing best fit to the theoretically proposed sequential two-site model. Besides the one, which had been shown previously in course of x-ray structure determination, a previously unrecognized binding site works in conjunction with an unbinding loop that facilitates liberation of hydrolyzed HA.

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The Skew of Polar Crown X-ray Arcades

International Astronomical Union Colloquium ◽

10.1017/s0252921100048041 ◽

1998 ◽

Vol 167 ◽

pp. 430-433 ◽

Cited By ~ 4

Author(s):

A.H. McAllister ◽

A.J. Hundhausen ◽

D. Mackay ◽

E. Priest

Keyword(s):

Magnetic Field ◽

Differential Rotation ◽

Flux Distribution ◽

Numerical Models ◽

Relative Orientation ◽

Axial Component ◽

Field Observations ◽

X Ray ◽

One To One ◽

The One

AbstractThe one-to-one relationship between the chirality of filament channels and the skew (relative orientation) of the overlying coronal arcades can be coupled with the predictions for the axial component of polar crown filaments based on past magnetic field observations to predict the skew of polar crown arcades in the recent cycle 22. We have surveyed the actual skew as seen in the Yohkoh SXT images over the declining phase of cycle 22 and found a result opposite to that expected. The SXT arcades have been compared with numerical models to show that while some of this result can be explained by flux distribution around switchbacks, other mechanisms such as differential rotation are also needed.

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DYNAMICS AND MAGNETIZATION IN GALAXY CLUSTER CORES TRACED BY X-RAY COLD FRONTS

The Astrophysical Journal ◽

10.1088/2041-8205/719/1/l74 ◽

2010 ◽

Vol 719 (1) ◽

pp. L74-L78 ◽

Cited By ~ 37

Author(s):

Uri Keshet ◽

Maxim Markevitch ◽

Yuval Birnboim ◽

Abraham Loeb

Keyword(s):

Galaxy Cluster ◽

X Ray ◽

Cold Fronts ◽

Cluster Cores

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Simulations of the merging galaxy cluster Abell 2034: what determines the level of separation between gas and dark matter

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3399 ◽

2020 ◽

Vol 500 (2) ◽

pp. 1858-1869 ◽

Cited By ~ 1

Author(s):

Micheli T Moura ◽

Rubens E G Machado ◽

Rogério Monteiro-Oliveira

Keyword(s):

Dark Matter ◽

Gravitational Lensing ◽

Galaxy Cluster ◽

X Rays ◽

X Ray ◽

History Of ◽

Hydrodynamical Simulations ◽

Cluster Mergers ◽

Cluster Cores ◽

Intracluster Gas

ABSTRACT Cluster mergers are an important laboratory for studying the behaviour of dark matter (DM) and intracluster gas. There are dissociative collisions that can separate the intracluster gas from the DM. Abell 2034 presents clear dissociative features observed by X-rays and gravitational lensing. The cluster, at z = 0.114, consists of two substructures with mass ratio of about 1:2.2, separated by ∼720 kpc. The X-ray emission peak is offcentred from the south DM peak by ∼350 kpc. Using N-body hydrodynamical simulations, we aim to reconstruct the dynamic history of the collision, reproducing the observed features, and also to explore the conditions that led to the dissociation. Our best model assuming that the collision is close to the plane of the sky, with a small impact parameter, observed 0.26 Gyr after central passage, reproduces the observed features of this cluster, such as the offset between X-ray and DM peaks, X-ray morphology, and temperatures. We explored several variations using different gas and DM concentrations for each cluster. The level of dissociation was quantified by the distances between X-ray and DM peaks, and also by the gas retention in the cluster cores. We found that the ratio of central gas densities is more important than the ratio of central DM densities in determining the level of dissociation.

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Thermal and non-thermal Sunyaev-Zel’dovich effect in the cavities of the galaxy cluster MS 0735.6+7421: the role of the thermal density in the cavity

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab732 ◽

2021 ◽

Author(s):

P Marchegiani

Keyword(s):

Galaxy Cluster ◽

Coulomb Interactions ◽

Frequency Range ◽

High Frequencies ◽

X Ray ◽

The Galaxy ◽

Sunyaev Zel'dovich Effect ◽

The One ◽

Very High

Abstract The galaxy cluster MS 0735.6+7421 hosts two large X-ray cavities, filled with radio emission, where a decrease of the Sunyaev-Zel’dovich (SZ) effect has been detected, without establishing if its origin is thermal (from a gas with very high temperature) or non-thermal. In this paper we study how thermal and non-thermal contributions to the SZ effect in the cavities are related; in fact, Coulomb interactions with the thermal gas modify the spectrum of low energy non-thermal electrons, which dominate the non-thermal SZ effect; as a consequence, the intensity of the non-thermal SZ effect is stronger for lower density of the thermal gas inside the cavity. We calculate the non-thermal SZ effect in the cavities as a function of the thermal density, and compare the SZ effects produced by thermal and non-thermal components, and with the one from the external Intra Cluster Medium (ICM), searching for the best frequency range where it is possible to disentangle the different contributions. We find that for temperatures inside the cavities higher than ∼1500 keV the non-thermal SZ effect is expected to dominate on the thermal one, particularly at high frequencies (ν > 500 GHz), where it can also be a non-negligible fraction of the SZ effect from the external ICM. We also discuss the possible sources of astrophysical bias (as kinetic SZ effect and foreground emission from Galactic dust) and possible ways to address them, as well as necessary improvements in the modeling of the properties of cavities and the ICM.

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The XMM Cluster Outskirts Project (X-COP): Thermodynamic properties of the intracluster medium out to R200 in Abell 2319

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731748 ◽

2018 ◽

Vol 614 ◽

pp. A7 ◽

Cited By ~ 25

Author(s):

V. Ghirardini ◽

S. Ettori ◽

D. Eckert ◽

S. Molendi ◽

F. Gastaldello ◽

...

Keyword(s):

Thermodynamic Properties ◽

Large Scale ◽

Signal To Noise Ratio ◽

Galaxy Cluster ◽

Pressure Profile ◽

Joint Analysis ◽

Gas Temperature ◽

X Ray ◽

The Galaxy ◽

High Level

Aims. We present the joint analysis of the X-ray and Sunyaev–Zel’dovich (SZ) signals in Abell 2319, the galaxy cluster with the highest signal-to-noise ratio in SZ Planck maps and that has been surveyed within our XMM-Newton Cluster Outskirts Project (X-COP), a very large program which aims to grasp the physical condition in 12 local (z < 0.1) and massive (M200 > 3 × 1014 M⊙) galaxy clusters out to R200 and beyond. Methods. We recover the profiles of the thermodynamic properties by the geometrical deprojection of the X-ray surface brightness, of the SZ Comptonization parameter, and accurate and robust spectroscopic measurements of the gas temperature out to 3.2 Mpc (1.6 R200), 4 Mpc (2 R200), and 1.6 Mpc (0.8 R200), respectively. We resolve the clumpiness of the gas density to be below 20% over the entire observed volume. We also demonstrate that most of this clumpiness originates from the ongoing merger and can be associated with large-scale inhomogeneities (the “residual” clumpiness). We estimate the total mass through the hydrostatic equilibrium equation. This analysis is done both in azimuthally averaged radial bins and in eight independent angular sectors, enabling us to study in detail the azimuthal variance of the recovered properties. Results. Given the exquisite quality of the X-ray and SZ datasets, their radial extension, and their complementarity, we constrain at R200 the total hydrostatic mass, modelled with a Navarro–Frenk–White profile at very high precision (M200 = 10.7 ± 0.5stat. ± 0.9syst. × 1014 M⊙). We identify the ongoing merger and how it is affecting differently the gas properties in the resolved azimuthal sectors. We have several indications that the merger has injected a high level of non-thermal pressure in this system: the clumping free density profile is above the average profile obtained by stacking Rosat/PSPC observations; the gas mass fraction recovered using our hydrostatic mass profile exceeds the expected cosmic gas fraction beyond R500; the pressure profile is flatter than the fit obtained by the Planck Collaboration; the entropy profile is flatter than the mean profile predicted from non-radiative simulations; the analysis in azimuthal sectors has revealed that these deviations occur in a preferred region of the cluster. All these tensions are resolved by requiring a relative support of about 40% from non-thermal to the total pressure at R200.

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Correlating sampling and intensity statistics in nanoparticle diffraction experiments

Journal of Applied Crystallography ◽

10.1107/s1600576715011747 ◽

2015 ◽

Vol 48 (4) ◽

pp. 1212-1227 ◽

Cited By ~ 6

Author(s):

Hande Öztürk ◽

Hanfei Yan ◽

John P. Hill ◽

I. Cevdet Noyan

Keyword(s):

Size Range ◽

Previous Article ◽

Diffraction Spot ◽

Reflection Band ◽

X Ray ◽

One To One ◽

The One ◽

Sampling Statistics ◽

Selection Of

In a previous article [Öztürk, Yan, Hill & Noyan (2014).J. Appl. Cryst.47, 1016–1025] it was shown that the sampling statistics of diffracting particle populations within a polycrystalline ensemble depended on the size of the constituent crystallites: broad X-ray peak breadths enabled some nano-sized particles to contribute more than one diffraction spot to Debye–Scherrer rings. Here it is shown that the equations proposed by Alexander, Klug & Kummer [J. Appl. Phys.(1948),19, 742–753] (AKK) to link diffracting particle and diffracted intensity statistics are not applicable if the constituent crystallites of the powder are below 10 nm. In this size range, (i) the one-to-one correspondence between diffracting particles and Laue spots assumed in the AKK analysis is not satisfied, and (ii) the crystallographic correlation between Laue spots originating from the same grain invalidates the assumption that all diffracting plane normals are randomly oriented and uncorrelated. Such correlation produces unexpected results in the selection of diffracting grains. For example, three or more Laue spots from a given grain for a particular reflection can only be observed at certain wavelengths. In addition, correcting the diffracted intensity values by the traditional Lorentz term, 1/cos θ, to compensate for the variation of particles sampled within a reflection band does not maintain fidelity to the number of poles contributing to the diffracted signal. A new term, cos θB/cos θ, corrects this problem.

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Influence of Rim Run-Out on the Nonuniformity of Tire-Wheel Assemblies

Tire Science and Technology ◽

10.2346/1.2139538 ◽

1994 ◽

Vol 22 (2) ◽

pp. 99-120 ◽

Cited By ~ 1

Author(s):

T. B. Rhyne ◽

R. Gall ◽

L. Y. Chang

Keyword(s):

Finite Element ◽

Radial Force ◽

Membrane Model ◽

Model Experiments ◽

Force Variation ◽

One To One ◽

The One

Abstract An analytical membrane model is used to study how wheel imperfections are converted into radial force variation of the tire-wheel assembly. This model indicates that the radial run-out of the rim generates run-out of the tire-wheel assembly at slightly less than the one to one ratio that was expected. Lateral run-out of the rim is found to generate radial run-out of the tire-wheel assembly at a ratio that is dependent on the tire design and the wheel width. Finite element studies of a production tire validate and quantify the results of the membrane model. Experiments using a specially constructed precision wheel demonstrate the behavior predicted by the models. Finally, a population of production tires and wheels show that the lateral run-out of the rims contribute a significant portion to the assembly radial force variation. These findings might be used to improve match-mounting results by taking lateral rim run-out into account.

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