Lyman-alpha clouds as a relic of primordial density fluctuations

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165923· OSTI ID:5339104

Bond, J R; Szalay, A S; Silk, J

Primordial density fluctuations are studied using a CDM model and primordial clouds some of which are expanding, driven by pressure gradients created when the medium is photionized, and some of which are massive enough to continue collapsing in spite of the pressure. Normalization of CDM models to the clustering properties on large scales are used to predict the parameters of collapsing clouds of subgalactic mass at early epochs. It is shown that the abundance and dimensions of these clouds are comparable to those of the Lyman-alpha systems. The evolutionary history of the clouds is computed, utilizing a spherically symmetric hydrodynamics code with the dark matter treated as a collisionless fluid, and the H I column density distribution is evaluated as a function of N(H I) and redshift. The observed cloud parameters come out naturally in the CDM model and suggest that Lyman-alpha clouds are the missing link between primordial density fluctuations and the formation of galaxies. 31 references.

• Research Organization: Toronto Univ. (Canada); NASA/Fermi National Accelerator Laboratory, Batavia, IL (USA); Eotvos Lorand Tudomanyeyetem, Budapest (Hungary); California Univ., Berkeley (USA)
• OSTI ID: 5339104
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 324; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640106* -- Astrophysics & Cosmology-- Cosmology
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC GASES
COSMOLOGY
DENSITY
ELECTROMAGNETIC RADIATION
FLUCTUATIONS
FLUID MECHANICS
FLUIDS
GALACTIC EVOLUTION
GALAXY CLUSTERS
GASES
HYDRODYNAMICS
INTERGALACTIC SPACE
IONIZATION
LYMAN LINES
MASS
MECHANICS
MICROWAVE RADIATION
NONLUMINOUS MATTER
PHOTOIONIZATION
PHYSICAL PROPERTIES
PRESSURE GRADIENTS
RADIATIONS
RELICT RADIATION
SPACE
VARIATIONS