Statistics – Computation
Scientific paper
Oct 1989
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1989apj...345...52k&link_type=abstract
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 345, Oct. 1, 1989, p. 52-58.
Statistics
Computation
16
Computational Astrophysics, Cosmology, Lyman Alpha Radiation, Quasars, Background Radiation, Evolution (Development), Red Shift, Spectral Line Width
Scientific paper
At sufficient resolution, QSO spectra can be examined for patches of reduced H I column density in Ly-alpha clouds. Statistics of these clearings can constrain the fraction of the ionizing background contributed by compact sources and (possibly) their lifetimes and beaming. This is demonstrated first in a simple Euclidean setup and then in a model which takes into account the expansion of the universe and the cosmological evolution of the factors involved. The expected number of clearings in a Ly-alpha forest extending back to the formation epoch of compact sources of ionizing radiation (CSIRs) is about 1/4, if the CSIRs are important ionizing agents, and if the transience of CSIRs is unimportant. The particular properties of the CSIR population, e.g., their luminosity function, have little importance. However, expected number of clearings can be much larger if the CSIR lifetimes are short compared to the light crossing times of the domains of dominance, or if the CSIRs turned on sharply at a time when the ionization rate due to competing processes was low.
Kovner Israel
Rees Martin J.
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