Skewering the universe with QSO lines of sight: Lyman alpha clouds as probes of large scale structure

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:7060287

Babul, A

The magnitude and the scale of clustering of Quasi-Stellar Objects (QSO) absorption lines provide potentially important clues about their origin and their spatial distribution. Such clues may aid in distinguishing between theories for the formation of large scale structure such as the Cold Dark Matter (CDM) models and explosion scenarios. Formation of low-mass objects is inevitable in the standard CDM cosmogony. Models were proposed seeking to identify these isolated low-mass condensates as Ly alpha clouds. However, the accompanying estimates of quantities such as the epoch of formation, or the number density of clouds, are not based on characteristics of isolated density peaks. Isolated peaks result primarily from power in a narrow band at the mass scale of the structures. First, a filter designed to study isolated density fluctuations is introduced. The filter is used to identify Ly alpha cloud candidates in a biased CDM model. If Ly alpha clouds have their origins in primordial density fluctuations, the CDM power spectrum does not have sufficient power on subgalactic scales to account for the observed structures. Further, theories such as the CDM model and the explosion scenario predict different spatial distributions for the Ly alpha clouds. Second, a formalism is developed for testing specific models for the three-dimensional spatial distributions of clouds against line-of-sight observations. The formalism is used to compute the redshift density of lines and the distribution of line intervals along a line-of-sight for the models, for comparison with the observations. Three simple models were considered: clouds arising from density fluctuations with a white noise power spectrum, clouds distributed on shells of constant comoving radii, and clouds restricted to shells expanding in a self-similar fashion.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 7060287
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIO SOURCES
COSMOLOGY
DATA
DISTRIBUTION
INFORMATION
LYMAN LINES
MASS
MATHEMATICAL MODELS
NONLUMINOUS MATTER
NUMERICAL DATA
QUASARS
RED SHIFT
SPATIAL DISTRIBUTION
STAR EVOLUTION
STAR MODELS
THEORETICAL DATA
UNIVERSE