Issue |
A&A
Volume 416, Number 2, March III 2004
|
|
---|---|---|
Page(s) | 447 - 466 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20034298 | |
Published online | 27 February 2004 |
CMB observations and the production of chemical elements at the end of the dark ages
1
Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching, Germany
2
Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow 117810, Russia
Corresponding author: K. Basu, kaustuv@mpa-garching.mpg.de
Received:
9
September
2003
Accepted:
4
December
2003
The metallicity evolution and ionization history
of the universe must leave its imprint on
the Cosmic Microwave Background
through resonant scattering of CMB photons by atoms, ions and
molecules. These transitions partially erase original temperature
anisotropies of the CMB, and also generate new fluctuations.
In this paper we propose a method to
determine the abundance of these heavy species in low density
(over-densities less than )
optically thin regions of the universe by using the unprecedented
sensitivity of current and future CMB experiments. In particular,
we focus our analysis on the sensitivity of the Planck HFI
detectors in four spectral bands. We also present
results for
and 810 which are of interest for balloon and
ground-based instruments, like ACT, APEX and SPT. We use the
fine-structure transitions of atoms and ions as a source of
frequency dependent optical depth (
). These transitions give
different contributions to the power spectrum of CMB
in different observing channels. By comparing
results from those channels, it is possible to avoid the limit imposed
by the cosmic variance and
to extract information about the abundance of corresponding species at the
redshift of scattering. For Planck HFI we will be able to get strong
constraints (
solar fraction) on the abundances of
neutral atoms like C, O, Si, S, and Fe in the redshift
range 1-50.
Fine-structure transitions of ions like CII, NII or OIII set similar
limits in the very important redshift range 3-25 and can be used to
probe the ionization history of the universe.
Foregrounds and other
frequency dependent contaminants may set a serious limitation
for this method.
Key words: cosmology: cosmic microwave background / cosmology: theory / galaxies: intergalactic medium / atomic processes / nuclear reactions, nucleosynthesis, abundances
© ESO, 2004
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