On the Direct Detectability of the Cosmic Dark Ages: 21-cm Emission from Minihalos


In the standard Cold Dark Matter (CDM) theory of structure formation, virialized minihalos (with Tvir . 10 4 K) form in abundance at high redshift (z > 6), during the cosmic “dark ages.” The hydrogen in these minihalos, the first nonlinear baryonic structures to form in the universe, is mostly neutral and sufficiently hot and dense to emit strongly at the 21-cm line. We calculate the emission from individual minihalos and the radiation background contributed by their combined effect. Minihalos create a “21-cm forest” of emission lines. We predict that the angular fluctuations in this 21-cm background should be detectable with the planned LOFAR and SKA radio arrays, thus providing a direct probe of structure formation during the “dark ages.” Such a detection will serve to confirm the basic CDM paradigm while constraining the background cosmology parameters, the shape of the power-spectrum of primordial density fluctuations, the onset and duration of the reionization epoch, and the conditions which led to the first stars and quasars. We present results here for the currentlyfavored, flat ΛCDM model, for different tilts of the primordial power spectrum. Subject headings: cosmology: theory — diffuse radiation — intergalactic medium — large-scale structure of universe — galaxies: formation — radio lines: galaxies

Cite this paper

@inproceedings{Iliev2002OnTD, title={On the Direct Detectability of the Cosmic Dark Ages: 21-cm Emission from Minihalos}, author={Ilian T. Iliev and Paul R . Shapiro and Andrea Ferrara and Hugo Martel}, year={2002} }