EDP Sciences
Free Access
Volume 393, Number 3, October III 2002
Page(s) 749 - 756
Section Cosmology
DOI https://doi.org/10.1051/0004-6361:20020929

A&A 393, 749-756 (2002)
DOI: 10.1051/0004-6361:20020929

Power spectrum of the cosmic infrared background at 60 and 100  $\mu$m with IRAS

M.-A. Miville-Deschênes1, G. Lagache2 and J.-L. Puget2

1  Laboratoire de Radioastronomie, École Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
2  Institut d'Astrophysique Spatiale, Université Paris-Sud, Bât. 121, 91405 Orsay, France

(Received 29 January 2002 / Accepted 17 June 2002)

Based on a power spectrum analysis of the IRAS ISSA maps, we present the first detection of the Cosmic far-Infrared Background (CIB) fluctuations at 60 and 100   $\mu$m. The power spectrum of 12 low cirrus emission regions is characterized by a power excess at spatial frequencies higher than $k \sim 0.02$ arcmin -1. Most of this excess is due to noise and to nearby point sources with a flux stronger than 1 Jy. But we show that when these contributions are carefully removed, there is still a power excess that is the signature of the CIB fluctuations. The power spectrum of the CIB at 60 and 100   $\mu$m is compatible with a Poissonian distribution, at spatial frequencies between 0.025 and 0.2 arcmin -1. The fluctuation level is ~ $ 1.6\times10^{3}$ Jy 2/sr and ~ $ 5.8\times10^{3}$ Jy 2/sr at 60 and 100   $\mu$m respectively. The levels of the fluctuations are used in a larger framework, with other observationnal data, to constrain the evolution of IR galaxies (Lagache et al. 2002). The detections reported here, coupled with the level of the fluctuations at 170  $\mu$m, give strong constraints on the evolution of the IR luminosity function. The combined results at 60, 100 and 170  $\mu$m for the CIB and its fluctuations allows, on the CIB at 60  $\mu$m, to put a firm upper limit of 0.27 MJy/sr and to give an estimate of 0.18 MJy/sr.

Key words: cosmology: diffuse radiation -- infrared: ISM -- infrared: general

Offprint request: M.-A. Miville-Deschênes, miville@lra.ens.fr

© ESO 2002

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