The determination of Q[SUB]0[/SUB] using X-ray and microwave observations of galaxy clusters

1978 ◽  
Vol 226 ◽  
pp. L103 ◽  
Author(s):  
J. Silk ◽  
S. D. M. White
Keyword(s):  
Galaxy Clusters ◽  
X Ray

scholarly journals A first determination of the surface density of galaxy clusters at very low x-ray fluxes

1995 ◽  
Vol 445 ◽  
pp. L11 ◽  
Author(s):  
Piero Rosati ◽  
Roberta della Ceca ◽  
Richard Burg ◽  
Colin Norman ◽  
Riccardo Giacconi
Keyword(s):  
Galaxy Clusters ◽  
Surface Density ◽  
X Ray ◽  
Low X

scholarly journals Mass determination of 5 relaxed galaxy clusters with Chandra X-ray data

2019 ◽  
Vol 1354 ◽  
pp. 012014
Author(s):  
H Wulandari ◽  
A H Fikri ◽  
K Vierdayanti ◽  
A N I Putri ◽  
D G Ramadhan
Keyword(s):  
Galaxy Clusters ◽  
Mass Determination ◽  
X Ray

scholarly journals Diffuse galaxy cluster emission at 168 MHz within the Murchison Widefield Array Epoch of Reionization 0-h field

2021 ◽  
Vol 38 ◽  
Author(s):  
S. W. Duchesne ◽  
M. Johnston-Hollitt ◽  
A. R. Offringa ◽  
G. W. Pratt ◽  
Q. Zheng ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Scaling Relations ◽  
Cluster Emission ◽  
X Ray ◽  
Diffuse Sources ◽  
Radio Halo ◽  
The Galaxy ◽  
Murchison Widefield Array

Abstract We detect and characterise extended, diffuse radio emission from galaxy clusters at 168 MHz within the Epoch of Reionization 0-h field: a $45^{\circ} \times 45^{\circ}$ region of the southern sky centred on R. A. ${}= 0^{\circ}$ , decl. ${}=-27^{\circ}$ . We detect 29 sources of interest; a newly detected halo in Abell 0141; a newly detected relic in Abell 2751; 4 new halo candidates and a further 4 new relic candidates; and a new phoenix candidate in Abell 2556. Additionally, we find nine clusters with unclassifiable, diffuse steep-spectrum emission as well as a candidate double relic system associated with RXC J2351.0-1934. We present measured source properties such as their integrated flux densities, spectral indices ( $\alpha$ , where $S_\nu \propto \nu^\alpha$ ), and sizes where possible. We find several of the diffuse sources to have ultra-steep spectra including the halo in Abell 0141, if confirmed, showing $\alpha \leq -2.1 \pm 0.1$ with the present data making it one of the steepest-spectrum haloes known. Finally, we compare our sample of haloes with previously detected haloes and revisit established scaling relations of the radio halo power ( $P_{1.4}$ ) with the cluster X-ray luminosity ( $L_{\textrm{X}}$ ) and mass ( $M_{500}$ ). We find that the newly detected haloes and candidate haloes are consistent with the $P_{1.4}$ – $L_{\textrm{X}}$ and $P_{1.4}$ – $M_{500}$ relations and see an increase in scatter in the previously found relations with increasing sample size likely caused by inhomogeneous determination of $P_{1.4}$ across the full halo sample. We show that the MWA is capable of detecting haloes and relics within most of the galaxy clusters within the Planck catalogue of Sunyaev–Zel’dovich sources depending on exact halo or relic properties.

scholarly journals Comparing different mass estimators for a large subsample of the Planck-ESZ clusters

2020 ◽  
Vol 644 ◽  
pp. A78
Author(s):  
L. Lovisari ◽  
S. Ettori ◽  
M. Sereno ◽  
G. Schellenberger ◽  
W. R. Forman ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Small Sample ◽  
Weak Lensing ◽  
Mass Measurements ◽  
X Ray ◽  
Mass Bias ◽  
Significant Difference ◽  
The Mean ◽  
Cluster Abundance

Context. Total mass is arguably the most fundamental property for cosmological studies with galaxy clusters. The individual cluster masses can be obtained with different methods, each with its own biases and limitations. Systematic differences in mass measurements can strongly impact the determination of the hydrostatic bias and of the mass-observable relations, key requirements of many cluster abundance studies. Aims. We investigate the present differences in the mass estimates obtained through independent X-ray, weak-lensing, and dynamical studies using a large subsample of the Planck-ESZ clusters. We also discuss the implications for mass bias analyses. Methods. After assessing the systematic differences in the X-ray-derived masses reported by distinct groups, we examine the mass estimates obtained with independent methods and quantify the differences as the mean ratio 1-b = MHE/MWL, dyn, where HE refers to hydrostatic masses obtained from X-ray observations, WL refers to the results of weak-lensing measurements, and dyn refers to the mass estimates either from velocity dispersion or from the caustic technique. So defined, the 1-b parameter includes all possible astrophysical, observational, and methodological biases in one single value. Results. Recent X-ray masses reported by independent groups show average differences smaller than ∼10%, posing a strong limit on the systematics that can be ascribed to the differences in the X-ray analysis when studying the hydrostatic bias. The mean ratio between our X-ray masses and the weak-lensing masses in the LC2-single catalog is 1-b = 0.74 ± 0.06, which corresponds to a mass bias of 26 ± 6%, a value insufficient to reconcile the Planck cluster abundance and cosmic microwave background results. However, the mean mass ratios inferred from the WL masses of different projects vary by a large amount, with APEX-SZ showing a bias consistent with zero (1-b = 1.02 ± 0.12), LoCuSS and CCCP/MENeaCS showing a significant difference (1-b = 0.76 ± 0.09 and 1-b = 0.77 ± 0.10, respectively), and WtG pointing to the largest deviation (1-b = 0.61 ± 0.12), which would substantially reduce the tension between the Planck results. Because of small differences between our M − YX relation and the one used by the Planck collaboration, our X-ray masses are on average 7% lower (4% at the same physical radius) than the Planck masses and can further reduce the required bias. At odds with the WL results, the dynamical mass measurements show better agreement with the X-ray hydrostatic masses, although there are significant differences when relaxed or disturbed clusters are used. However, the comparison is currently limited by the small sample sizes. Conclisions. The systematic differences between total masses obtained with recent independent X-ray analyses are smaller than those found in previous studies. This shifts the focus to WL and dynamical studies for a better convergence of the level of mass bias. However, the ratios obtained using different mass estimators suggest that there are still systematics that are not accounted for in all the techniques used to recover cluster masses. This prevents the determination of firm constraints on the level of hydrostatic mass bias in galaxy clusters.

scholarly journals Measurement of the cosmological distance scale using X-ray and Sunyaev–Zel'dovich effect observations of galaxy clusters

2012 ◽  
Vol 8 (S289) ◽  
pp. 339-343
Author(s):  
Massimiliano Bonamente ◽  
John Carlstrom ◽  
Eric Leitch ◽  
Marshall Joy ◽  
Daniel Marrone ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Owens Valley ◽  
Radio Observatory ◽  
X Ray ◽  
Cosmological Distance Scale ◽  
Systematic Uncertainties ◽  
Sunyaev Zel'dovich Effect

AbstractX-ray and Sunyaev–Zeldovich effect (SZE) observations of galaxy clusters can be used to measure their distances independently of the cosmic distance ladder. We have determined the distance to 38 clusters of galaxies in the redshift range 0.14 ≤ z ≤ 0.89 using X-ray data from the Chandra X-ray Observatory and SZE data from the Owens Valley Radio Observatory and the Berkeley–Illinois–Maryland Association interferometric arrays. We measure a Hubble constant of H0 = 76.9+3.9−3.4+10.0−8.0 km s−1 Mpc−1 (statistical followed by systematic uncertainties at 68% confidence) for an ΩM=0.3, ΩΛ=0.7 cosmology. Our determination of the Hubble parameter in the distant Universe agrees with measurements from the Hubble Space Telescope Key Project that probed the nearby Universe.

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

Polarity Determination in Sphalerite and Wurtzite Structures

1990 ◽  
Vol 48 (2) ◽  
pp. 500-501
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Opposite Polarity ◽  
Single Domain ◽  
Polar Material ◽  
Electron Microscopic ◽  
Dynamical Interaction ◽  
X Ray ◽  
Polarity Determination ◽  
The Absolute ◽  
Microscopic Techniques

The determination of the absolute polarity of a polar material is often crucial to the understanding of the defects which occur in such materials. Several methods exist by which this determination may be performed. In bulk, single-domain specimens, macroscopic techniques may be used, such as the different etching behavior, using the appropriate etchant, of surfaces with opposite polarity. X-ray measurements under conditions where Friedel’s law (which means that the intensity of reflections from planes of opposite polarity are indistinguishable) breaks down can also be used to determine the absolute polarity of bulk, single-domain specimens. On the microscopic scale, and particularly where antiphase boundaries (APBs), which separate regions of opposite polarity exist, electron microscopic techniques must be employed. Two techniques are commonly practised; the first [1], involves the dynamical interaction of hoLz lines which interfere constructively or destructively with the zero order reflection, depending on the crystal polarity. The crystal polarity can therefore be directly deduced from the relative intensity of these interactions.

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