Published in ApJ, 503, 518, 1998.
For a PDF version of the article, click
here.
ABSTRACT. We present an estimate of the global budget of
baryons in all states, with conservative estimates of the
uncertainties, based on all relevant information we have been
able to marshal. Most of the baryons today are still in the
form of ionized gas, which contributes a mean density uncertain
by a factor of about four.
Stars and their remnants are a relatively minor component,
comprising or our best-guess plasma density
only about 17% of the baryons, while
populations contributing most of the blue starlight comprise
less than 5%. The formation of galaxies and of stars within
them appears to be a globally inefficient process.
The sum over our budget, expressed as a fraction
of the critical Einstein-de Sitter density, is in the range
0.007 
B 0.041,
with a best guess B ~ 0.021 (at Hubble constant
70 km s-1 Mpc-1). The central value agrees with the
prediction from the theory of light element production and
with measures of the density of intergalactic plasma at redshift
z ~ 3. This apparent concordance
suggests we may be
close to a complete survey of the major states of the baryons.
Keywords : cosmology: observations - galaxies: fundamental parameters
Table of Contents
