ar X iv : a st ro - p h / 98 03 03 0 v 1 4 M ar 1 99 8 The seeds of rich galaxy clusters in the Universe
نویسندگان
چکیده
The discovery[1] of a population of young galaxies at an epoch when the universe was about one tenth of its current age has shed new light on the question of when and how galaxies formed. Within the context of popular models[2] this is the population of primeval galaxies that built themselves up to the size of present–day galaxies through the process of repeated mergers. But the recent detection [3] of a large concentration of these primeval galaxies appears to be incompatible with hierarchical clustering models, which generally predict that clusters of this size are fully formed later in time. Here we use a combination of two powerful theoretical techniques –semi-analytic modelling and N-body simulations– to show that such large concentrations should be quite common in a universe dominated by cold dark matter, and that they are the progenitors of the rich galaxy clusters seen today. We predict the clustering properties of primeval galaxies which should, when compared with data that will be collected in the near future, test our understanding of galaxy formation within the framework of a universe dominated by cold dark matter. The longstanding search for primeval galaxies was recently brought to fruition by the combination of deep imaging and Keck Telescope spectroscopy [4]. Because they were originally identified by a sharp break in their spectrum, at the wavelength corresponding to the limit of the Lyman series of hydrogen, these galaxies are called " Lyman break " galaxies. The most distant examples have redshift z ≃ 3.5, corresponding to the time when the universe was only about 10% of its current age. The structure discovered by Steidel and collaborators[3] appears as a spike in the redshift distribution at z = 3.09. It contains 15 Lyman-break galaxies in a 9 × 18 arcminute field [3]. The comoving spatial dimensions of this structure are huge, approximately 8×10×13h −1 Mpc in a Universe with critical density. (Throughout, we denote Hubble's constant as H 0 = 100hkms −1 Mpc −1 .) The current paradigm for the formation of cosmic structure is the cold dark matter theory [5]. For suitable values of the parameters, this theory provides a good description of large-scale structure, from scales probed by microwave background anisotropy measurements to those mapped by galaxy surveys [6]. In this theory, galaxies form by gas cooling and condensing into dark matter halos which grow by accretion and mergers in a hierarchical fashion. There …
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 / 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 کاملX iv : a st ro - p h / 98 03 05 9 v 1 6 M ar 1 99 8 On the role of shock waves in galaxy cluster evolution
Received ; accepted – 2 – ABSTRACT Numerical simulations of galaxy clusters including two species – baryonic gas and dark matter particles – are presented. Cold Dark Matter spectrum, Gaussian statistics and flat universe are assumed. The dark matter component is evolved numerically by means of a standard particle mesh method. The evolution of the baryonic component has been studied numerically ...
متن کاملar 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
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 ...
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 03 10 8 v 1 1 0 M ar 1 99 8 Mid - infrared [ NeII ] line emission from the nucleus of NGC 253
We report on mid-infrared (MIR) continuum and line emission mapping of the nucleus of NGC 253. The data, with a resolution of 1.4, reveal a double-peaked arc-like [NeII] emission region. Comparison with published data shows that the [NeII] arc is centered on the nucleus of the galaxy. The brightest [NeII] source coincides with the infrared continuum peak. The interpretation of these results is ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1998