ar X iv : a st ro - p h / 98 03 27 7 v 1 2 4 M ar 1 99 8 The Most Massive Distant Clusters : Determining Ω and σ 8
نویسندگان
چکیده
The existence of the three most massive clusters of galaxies observed so far at z > 0.5 is used to constrain the mass density parameter of the universe, Ω, and the amplitude of mass fluctuations, σ 8. We find Ω=0.2 −0.4 (95 %). We show that the existence of even the single most distant cluster at z=0.83, MS1054–03, with its large gravitational lensing mass, high temperature, and large velocity dispersion, is sufficient to establish powerful constraints. High-density, Ω=1 (σ 8 ≃0.5–0.6) Gaussian models are ruled out by these data (∼ < 10 −6 probability); the Ω=1 models predict only ∼ 10 −5 massive clusters at z > 0.65 (∼ 10 −3 at z > 0.5) instead of the 1 (3) clusters observed.
منابع مشابه
ar X iv : a st ro - p h / 98 03 21 2 v 1 1 8 M ar 1 99 8 Anisotropy of CMB & Cosmological Model
In this brief review I will touch upon the main points and trends of observational and theoretical cosmology, that influence and change today our understanding of the Universe.
متن کاملar X iv : a st ro - p h / 97 11 03 5 v 1 4 N ov 1 99 7 CLUSTERS IN VARIOUS COSMOLOGICAL MODELS : ABUNDANCE AND EVOLUTION
The combination of measurements of the local abundance of rich clusters of galaxies and its evolution to higher redshift offers the possibility of a direct measurement of Ω 0 with little contribution from other cosmological parameters. We investigate the significance of recent claims that this evolution indicates that Ω 0 must be small. The most recent cluster velocity dispersion function 1 fro...
متن کاملar X iv : a st ro - p h / 98 03 15 5 v 1 1 3 M ar 1 99 8 Deep ISOCAM Observations of Abell 2218
We report on the mid-infrared imaging at 5, 7, 10 & 15 µm of the galaxy cluster Abell 2218 obtained with the ISOCAM instrument onboard ESA's Infrared Space Observatory (ISO), as part of an ongoing program to image gravitational arcs and arclets in distant clusters. Several cluster galaxies as well as field galaxies are detected. We discuss their mid-IR flux properties.
متن کاملar X iv : a st ro - p h / 98 04 15 2 v 1 1 6 A pr 1 99 8 New aspects in the theory of magnetic winds from massive hot stars
متن کامل
ar X iv : a st ro - p h / 98 03 03 9 v 1 4 M ar 1 99 8 Cosmology With High - Redshift Water Masers
Multi-epoch VLBA observations of the maser in NGC 4258 have yielded a 4% geometrical distance to the galaxy. The potential scientific payoffs of finding similar objects at large distances, in the Hubble flow, are considerable. In this contribution, I discuss the plausibility of detecting high-redshift water masers, and describe a search strategy that we have implemented to realize this objective.
متن کامل