Cluster Mass Estimate and a Cusp of the Mass‐Density Distribution in Clusters of Galaxies

1999 ◽  
Vol 512 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Nobuyoshi Makino ◽  
Katsuaki Asano
Keyword(s):  
Density Distribution ◽  
Mass Density ◽  
Clusters Of Galaxies ◽  
Cluster Mass ◽  
Mass Estimate

scholarly journals Measuring the Autocorrelation Function of Nanoscale Three-Dimensional Density Distribution in Individual Cells Using Scanning Transmission Electron Microscopy, Atomic Force Microscopy, and a New Deconvolution Algorithm

2017 ◽  
Vol 23 (3) ◽  
pp. 661-667 ◽  
Author(s):  
Yue Li ◽  
Di Zhang ◽  
Ilker Capoglu ◽  
Karl A. Hujsak ◽  
Dhwanil Damania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Density Distribution ◽  
Scanning Transmission Electron Microscopy ◽  
Mass Density ◽  
Three Dimensional ◽  
Force Microscopy ◽  
Statistical Measures ◽  
Atomic Force ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractEssentially all biological processes are highly dependent on the nanoscale architecture of the cellular components where these processes take place. Statistical measures, such as the autocorrelation function (ACF) of the three-dimensional (3D) mass–density distribution, are widely used to characterize cellular nanostructure. However, conventional methods of reconstruction of the deterministic 3D mass–density distribution, from which these statistical measures can be calculated, have been inadequate for thick biological structures, such as whole cells, due to the conflict between the need for nanoscale resolution and its inverse relationship with thickness after conventional tomographic reconstruction. To tackle the problem, we have developed a robust method to calculate the ACF of the 3D mass–density distribution without tomography. Assuming the biological mass distribution is isotropic, our method allows for accurate statistical characterization of the 3D mass–density distribution by ACF with two data sets: a single projection image by scanning transmission electron microscopy and a thickness map by atomic force microscopy. Here we present validation of the ACF reconstruction algorithm, as well as its application to calculate the statistics of the 3D distribution of mass–density in a region containing the nucleus of an entire mammalian cell. This method may provide important insights into architectural changes that accompany cellular processes.

The Effect of Neutrinos on the Formation Time of Rich Clusters of Galaxies

1981 ◽  
Vol 4 (2) ◽  
pp. 181-182 ◽  
Author(s):  
B. M. Lewis
Keyword(s):  
Globular Clusters ◽  
Relaxation Mechanism ◽  
Elliptical Galaxies ◽  
Formation Time ◽  
Clusters Of Galaxies ◽  
Cluster Mass ◽  
Cluster Of Galaxies ◽  
Universal Expansion ◽  
Hubble Time

Both the radial and the velocity distributions of galaxies within rich clusters are well described by the isothermal distribution (e.g. Lewis 1978 and 1979). It is tempting to ascribe this apparently relaxed state to the operation of Lynden-BeU’s (1967) violent relaxation mechanism, during the initial coherent collapse on the proto-cluster, after it brakes itself against the universal expansion. This scenario explains the isothermal distribution observed in elliptical galaxies and globular clusters. When applied to a cluster of galaxies made up of baryons, however, the timescale for the scenario is comparable with the Hubble time H−1. The situation changes if most of the cluster mass is contributed by neutrinos.

scholarly journals Scattering of Planetesimals from Young Planetary Disks: Application to the β Pictoris System

2002 ◽  
Vol 12 ◽  
pp. 225-228
Author(s):  
Hervé Beust ◽  
Philippe Thébault
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Mass Density ◽  
Mean Motion Resonances ◽  
Dynamical Characteristics ◽  
Mean Motion ◽  
Mass Estimate ◽  
Plausible Mechanism ◽  
Dynamical Origin

AbstractTransient redshifted events monitored in the spectrum ofβPictoris have been interpreted as resulting from the evaporation of numerous comet-like bodies in the vicinity of this star. The dynamical origin for this phenomenon is attributed to mean-motion resonances (4:1 and 3:1) with a Jovian-like planet. Numerical simulations of this phenomenon are able to correctly reproduce the dynamical characteristics of the star-grazers observed. The numerical study allows to estimate the density of the planetesimal disk from which the bodies are supposed to originate, i.e. ∼ a few 108bodies per AU. A key issue with this model is the refilling of the resonances, as without refilling they should be cleared within a few 105yr and the observed phenomenon should stop. Collisions among planetesimals are a plausible mechanism. Collisional simulations show that collisions are able to sustain the observed phenomenon over much more than 106yr, provided the population of the disk is high enough. The mass density of this population is estimated to a few tens of Earth masses per AU, which is only marginally realistic. However, the mass estimate is very poorly constrained.

scholarly journals Beltrami Equation And Cluster Lensing

1996 ◽  
Vol 173 ◽  
pp. 153-154
Author(s):  
T. Schramm
Keyword(s):  
Mass Density ◽  
Beltrami Equation ◽  
Clusters Of Galaxies

Arclets in clusters of galaxies can be used to determine the lens mapping and not only to constrain the mass density of the cluster. Multiply imaged arclets are therefore easily identified without further modeling.

scholarly journals The dark matter halos of spheroidal galaxies and clusters of galaxies

2004 ◽  
Vol 220 ◽  
pp. 159-164 ◽  
Author(s):  
Tommaso Treu ◽  
Léon V. E. Koopmans ◽  
David J. Sand ◽  
Graham P. Smith ◽  
Richard S. Ellis
Keyword(s):  
Dark Matter ◽  
Mass Density ◽  
Hubble Constant ◽  
Dark Matter Halo ◽  
Dynamical Analysis ◽  
Delay Systems ◽  
Clusters Of Galaxies ◽  
Dark Matter Halos ◽  
Gravitational Lenses ◽  
Stellar Component

We describe the first results from two observational projects aimed at measuring the amount and spatial distribution of dark matter in distant early-type galaxies (E/S0s) and clusters of galaxies. At the galaxy scale, the Lenses Structure and Dynamics (LSD) Survey is gathering kinematic data for distant (up to z ⋐ 1) E/S0s that are gravitational lenses. A joint lensing and dynamical analysis constrains the fraction of dark matter within the Einstein radius, the mass-to-light ratio of the stellar component, and the total slope of the mass density profile. These properties and their evolution with redshift are briefly discussed in terms of the formation and evolution of E/S0 galaxies and measurement of the Hubble Constant from gravitational time delay systems. At the cluster scale – after careful removal of the stellar component with a joint lensing and dynamical analysis – systems with giant radial arcs can be used to measure precisely the inner slope of the dark matter halo. An HST search for radial arcs and the analysis of a first sample are briefly discussed in terms of the universal dark matter halos predicted by CDM simulations.

AXIAL ELECTROMAGNETIC FORCE DENSITY IN MPD THRUSTERS

1992 ◽  
Vol 06 (23) ◽  
pp. 1465-1474
Author(s):  
T.S. SHESHADRI
Keyword(s):  
Density Distribution ◽  
Axial Force ◽  
Electromagnetic Force ◽  
Mass Density ◽  
Force Density ◽  
Viscous Effects ◽  
Inlet Velocity ◽  
Large Force ◽  
Hall Parameter ◽  
Mpd Thrusters

An MPD thruster formulation involving coupled aerothermodynamic-electromagnetic equations and including viscous effects is developed and solved. The electromagnetic force density distribution in the thruster interior is studied. Axial force densities are found to be largest on the cathode longitudinal surface. Very large force densities are found at the cathode upstream end and this is attributed to large values of the Hall parameter. Over the rest of the cathode longitudinal surface, axial force densities increase with increasing inlet velocities and mass densities and larger plasma viscosities. Equivalent increases in inlet velocity and mass density produce effects of different magnitudes.

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