Statistics of the hubble diagram. II. The form of the luminosity function and density variations with application to quasars
New techniques for deriving a luminosity function LF and a spatial density distribution rho (r) from magnitude-redshift data are presented. These techniques do not require iterative improvement of an initially guessed solution or the adoption of arbitrary analytic forms; instead, they provide explicit numerical estimates of the LF and rho (r). Thus, sources of systematic uncertainty are eliminated. This is achieved at the cost of an increase in the statistical noise. As in Paper I of this series, it is necessary to assume that the LF does not vary in functional form. An internal test of this assumption is described.These techniques are illustrated by application to a sample of 3 CR and 4C quasars. The radio luminosity function is found to be a steep power law with no features. The optical luminosity function is found to be a shallow power law cut off roughly exponentially above a characteristic luminosity L/sub opt/* (Z) corresponding roughly to M/sub B/=-22-6 log (1+Z) The comoving density evolution is not well fitted by any simple function of 1+Z (e.g., (1+Z)/sup 6/ errs by factors as large as approx.5 at some redshifts) but is well represented by an exponential of look-back time. Specific analytic fits and numerical tabulations are given for each of these functions. The constant LF form assumption is found to be a reasonable first approximation for the quasars.Other possible applications of the new methods to problems in extragalactic and stellar astronomy are suggested.
- Research Organization:
- Harvard-Smithsonian Center for Astrophysics
- OSTI ID:
- 5789074
- Journal Information:
- Astrophys. J.; (United States), Vol. 231:3
- Country of Publication:
- United States
- Language:
- English
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Statistics of the Hubble diagram. I. Determination of q/sub 2/ and luminosity evolution with application to quasars
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GENERAL PHYSICS
COSMOLOGY
LUMINOSITY
RED SHIFT
STATISTICS
QUASARS
COSMOLOGICAL MODELS
FUNDAMENTAL CONSTANTS
SPATIAL DISTRIBUTION
COSMIC RADIO SOURCES
DISTRIBUTION
MATHEMATICAL MODELS
MATHEMATICS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
640106* - Astrophysics & Cosmology- Cosmology