scholarly journals Multimass Models for Clusters of Galaxies

1983 ◽  
Vol 104 ◽  
pp. 325-325
Author(s):  
A. Mazure ◽  
G. des Forêts ◽  
D. Gerbal ◽  
G. Mathez ◽  
E. Salvador-Solé
Keyword(s):  
Surface Brightness ◽  
Dynamical Analysis ◽  
Careful Examination ◽  
Numerical Density ◽  
Clusters Of Galaxies ◽  
Density Profiles ◽  
X Ray ◽  
Luminous Matter ◽  
Flat Rotation Curves ◽  
Massive Neutrinos

It is now a widely spread opinion that a ratio of 10:1 between dark and luminous matter exists. Supported by the existence of flat rotation curves at large radii for spirals, this fact reinforces cosmological scenarios with, for instance, massive neutrinos. This content of dark matter is often estimated from the dynamical analysis of clusters of galaxies based essentially on the application of the Virial theorem or the monomassive Emden sphere or deduced from numerical simulations. However, a careful examination shows crucial failures in such approaches1, at least the lack of a mass spectrum and/or of a dynamically influent Intra Cluster Medium. This has been included in simple models1 together with other realistic features such as temperature gradient, isovelocity and/or isothermicity of the gravitational plasma. Our aim is thus to account simultaneously for all the available data concerning both galaxies and ICM; namely, the Nonisothermal Multimass Models1 allow us to fit jointly the numerical density profiles of galaxies, the luminosity function, the velocity dispersion profiles versus magnitude or radius, the luminosity segregation2, the X-ray temperature, luminosity and surface brightness profiles.

scholarly journals ASCA Observations of Three Gravitational Lensing Clusters of Galaxies; CL0500-24, CL2244-02, and A370

1998 ◽  
Vol 188 ◽  
pp. 319-320
Author(s):  
Naomi Ota ◽  
Kazuhisa Mitsuda ◽  
Yasushi Fukazawa
Keyword(s):  
Gravitational Lensing ◽  
Surface Brightness ◽  
Clusters Of Galaxies ◽  
X Ray

We determined the X-ray temperatures of three gravitational lensing clusters, CL0500-24, CL2244-02, and A370, and obtained significant constraints on the surface brightness profile assuming the β-model and the King model profiles. The mass of the cluster estimated from these X-ray data is by a factor of two to three smaller than the mass estimated from lens models for two of the clusters.

scholarly journals Development of New Analysis Method for Mapping Observations of Clusters of Galaxies

1998 ◽  
Vol 188 ◽  
pp. 312-313
Author(s):  
K. Kikuchi ◽  
T. Ohashi ◽  
H. Ezawa ◽  
M. Hirayama ◽  
H. Honda ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Stray Light ◽  
Physical Parameters ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
X Ray ◽  
Hot Gas ◽  
Cluster Data ◽  
Metal Abundance ◽  
Analysis System

Mapping observations of nearby large-extended clusters of galaxies (Coma, Perseus, Virgo, etc.) are being performed with ASCA. Such clusters allow us to map physical parameters of hot gas in the clusters, such as temperature, metal abundance, and X-ray surface brightness. To determine such parameters at each part of a cluster, one should take careful care of X-ray contamination from outside of a pointed field, which is mainly due to “stray-light” X-rays (Honda et al. 1997). For this reason, the only way to obtain the distribution of hot gas parameter is to process the whole cluster data in a self-consistent way. For this purpose, we are developing the new analysis system called TERRA.

scholarly journals The Scaling Relations for Clusters of Galaxies

1998 ◽  
Vol 179 ◽  
pp. 268-269
Author(s):  
J. Annis
Keyword(s):  
Surface Brightness ◽  
Scaling Relations ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Large Samples

The dominant baryonic component of clusters of galaxies is their X-ray emitting atmosphere. X-ray surveys have made it possible to examine this component in large samples of clusters. David et al. (1993) provided a catalog of X-ray temperatures. I have measured 79 clusters from that list using Einstein IPC data (Harris et al. 1990), determining several measures of the radius. The most useful turns out to be the Petrosian radius. Given a radius, one can measure the surface brightness at that position.

scholarly journals Hot Gas in Clusters of Galaxies

1980 ◽  
Vol 5 ◽  
pp. 387-396
Author(s):  
J. L. Culhane
Keyword(s):  
Surface Brightness ◽  
Luminosity Function ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
Will Emit ◽  
X Ray ◽  
Hot Gas ◽  
Sky Survey ◽  
To Come ◽  
Einstein Observatory

The discovery of extended X-ray sources associated with clusters of galaxies which resulted from the Uhuru X-ray sky survey was one of the most important observations to come from that programme. Following Uhuru, the Ariel V and HEAO-1 sky surveys have found many more cluster X-ray sources and the recently launched Einstein observatory has begun to increase further the number of identifications. However there is in any case evidence from the X-ray cluster luminosity function that all rich clusters of galaxies will emit X-rays at some level.Preliminary results from the Einstein observatory (Murray, 1979) suggest that the extended X-ray emission from centrally condensed (cD) clusters is itself centrally condensed and spherically symmetrical in appearance. However irregular clusters have non-uniform X-ray surface brightness distributions. In addition there are some galaxies in clusters of irregular morphology that have associated X-ray halos.

scholarly journals X-Ray Substructures of BCS, NORAS, REFLEX, Radio Halos/Relics and Cooling Flow Clusters of Galaxies

2002 ◽  
Vol 12 ◽  
pp. 519-521 ◽  
Author(s):  
Peter Schuecker ◽  
Hans Böhringer ◽  
Luigina Feretti
Keyword(s):  
Systematic Study ◽  
Surface Brightness ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Radio Halo ◽  
Cooling Flow ◽  
Cluster Morphology ◽  
Density Relation ◽  
Radio Halos

AbstractThe results of a systematic study of substructures in X-ray surface brightness distributions of BCS, NORAS, REFLEX, radio halo, relic, and cooling flow clusters of galaxies based on RASS data are presented. At least 40 percent of the clusters show substructure. Indications for a cluster morphology-density relation are found. The fraction of clusters with substructure seems to be higher for halo and relic clusters and lower for clusters with cooling flow signature.

scholarly journals What does the Dynamical Analsis of Clusters of Galaxies Tell us About Massive Neutrinos?

1983 ◽  
Vol 104 ◽  
pp. 321-323
Author(s):  
G. Des Forêts ◽  
D. Gerbal ◽  
G. Mathez ◽  
A. Mazure ◽  
E. Salvador-Solé
Keyword(s):  
Numerical Density ◽  
Clusters Of Galaxies ◽  
Baryonic Matter ◽  
Missing Mass ◽  
Mass Problem ◽  
Inhomogeneous Systems ◽  
Massive Neutrinos ◽  
Jeans Instability

It is often claimed that massive neutrinos (v's) can solve the “missing mass” problem, but it is not so clear in the particular case of clusters of galaxies (C.O.G.). Let us assume that the unseen matter is composed by massive v's only. If they are cosmological, the v's should obey Fermi-Dirac statistics with a density of ∼ 100 v/cm3/species. But if “relic,” the v's would be so slow (1) that they cannot exist in this form (because of the previous Jeans instability or because they are trapped in wells generated by baryonic matter). Since the time when the v's decoupled from the primeval mixture (T ∼ 3–1 MeV), the v's can be considered as a “gravitational plasma,” so that violent relaxation occurs in inhomogeneous systems, leading to a Lynden-Bell distribution defined by three parameters: ην (numerical density), Vv (r.m.s. velocity) and the v-mass, mv, all unknown. All three of these parameters are, in fact, necessary to define a state of v-matter.

Sign in / Sign up

Export Citation Format

Share Document