Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2011-05-07
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
13 pages, 14 figures, accepted for publication by A&A
Scientific paper
The anisotropies of the cosmic infrared background (CIB) are a powerful tool to study the evolution of galaxies and large-scale structures. However one of the main limitations to an accurate measurement is the contamination by Galactic dust emission. Our goal is to show that we can remove the Galactic cirrus contamination using HI data, and thus measure accurately the clustering of starburst galaxies in the CIB. We use observations of the extragalactic N1 field at far-infrared (100 and 160 um) and radio (21 cm) wavelengths. We compute the correlation between dust emission, as traced by far-infrared observations, and HI gas, and derive dust emissivities which enable us to subtract the cirrus emission from the far-infrared maps. We then derive the power spectrum of the CIB anisotropies and its mean level. We compute dust emissivities for each of the HI-velocity components. Using IRIS/IRAS data at 100 um, we demonstrate that we can use the measured emissivities to determine and remove the cirrus contribution to the power spectrum of the CIB. We then apply this method at 160 um with Spitzer/MIPS data. We measure correlated anisotropies at 160 um, and for the first time at 100 um. We also combine the HI data and Spitzer total power mode absolute measurements to determine the CIB mean level at 160 um. We find B160 = 0.77+/-0.04+/-0.12 MJy/sr where the first error is statistical and the second one is systematic. Combining this measurement with the 100/160 color of the correlated anisotropies, we also derive the cosmic infrared background mean at 100 um, B100 = 0.22+/-0.06+/-0.07 MJy/sr where the error are the same as previously. This measurement is in line with values obtained with recent models of infrared galaxy evolution and Herschel/PACS data, but is much smaller than the previous DIRBE measurements.
Blagrave Kevin
Grain Julien
Lagache Guilaine
Lockman Felix J.
Martin Peter
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