EDP Sciences
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Volume 425, Number 1, October I 2004
Page(s) 9 - 14
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20034448

A&A 425, 9-14 (2004)
DOI: 10.1051/0004-6361:20034448

Dust from reionization

E. Elfgren1 and F.-X. Désert2

1  Department of Physics, Luleå University of Technology, 971 87 Luleå, Sweden
    e-mail: elf@ludd.luth.se
2  Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 414 rue de la piscine, 38041 Grenoble Cedex 9, France

(Received 6 October 2003 / Accepted 13 May 2004 )

The possibility that population III stars have reionized the Universe at redshifts greater than 6 has recently gained momentum with WMAP polarization results. Here we analyse the role of early dust produced by these stars and ejected into the intergalactic medium. We show that this dust, heated by the radiation from the same population III stars, produces a submillimetre excess. The electromagnetic spectrum of this excess could account for a significant fraction of the FIRAS (Far Infrared Absolute Spectrophotometer) cosmic far infrared background above 700 micron. This spectrum, a primary anisotropy ( $\Delta T$) spectrum times the  $\nu^2$ dust emissivity law, peaking in the submillimetre domain around 750 micron, is generic and does not depend on other detailed dust properties. Arcminute-scale anisotropies, coming from inhomogeneities in this early dust, could be detected by future submillimetre experiments such as Planck HFI.

Key words: cosmology: cosmic microwave background -- cosmology: early Universe

© ESO 2004