HerMES: deep number counts at 250 μm, 350 μm and 500 μm in the COSMOS and GOODS-N fields and the build-up of the cosmic infrared background - CEA - Commissariat à l’énergie atomique et aux énergies alternatives Access content directly
Journal Articles Astronomy and Astrophysics - A&A Year : 2012

HerMES: deep number counts at 250 μm, 350 μm and 500 μm in the COSMOS and GOODS-N fields and the build-up of the cosmic infrared background

1 AIM (UMR_7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
2 IAS - Institut d'astrophysique spatiale
3 LAM - Laboratoire d'Astrophysique de Marseille
4 CASA - Center for Astrophysics and Space Astronomy [Boulder]
5 ARC - NASA Ames Research Center
6 ROE - Royal Observatory Edinburgh
7 MPE - Max-Planck-Institut für Extraterrestrische Physik
8 Computing and Mathematical Sciences [Pasadena]]
9 UH - University of Hawai'i [Honolulu]
10 IAC - Instituto de Astrofisica de Canarias
11 UCM - Universidad Complutense de Madrid = Complutense University of Madrid [Madrid]
12 Imperial College London
13 UC Irvine - University of California [Irvine]
14 Caltech Department of Astronomy [Pasadena]
15 School of Physics and Astronomy [Cardiff]
16 Astronomy Centre, University of Sussex
17 Dipartimento di Astronomia [Padova]
18 University of Colorado [Boulder]
19 ESO - European Southern Observatory
20 IAP - Institut d'Astrophysique de Paris
21 Dipartimento di Fisica e Astronomia "Galileo Galilei"
22 UBC - University of British Columbia
23 JPL - Jet Propulsion Laboratory
24 CALTECH - California Institute of Technology
25 MSSL - Mullard Space Science Laboratory
26 RAL Space - Space Science and Technology Department [Didcot]
27 University of Lethbridge
28 MPE - Max Planck Institute for Extraterrestrial Physics
29 Cardiff University
30 MPIA - Max-Planck-Institut für Astronomie
31 CfA - Harvard-Smithsonian Center for Astrophysics
32 ESA - Agence Spatiale Européenne = European Space Agency
Guilaine Lagache
H. Aussel
A. Boselli
V. Buat
M. Pohlen
  • Function : Author


Aims. The Spectral and Photometric Imaging REceiver (SPIRE) onboard the Herschel space telescope has provided confusion limited maps of deep fields at 250 μm, 350 μm, and 500 μm, as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). Unfortunately, due to confusion, only a small fraction of the cosmic infrared background (CIB) can be resolved into individually-detected sources. Our goal is to produce deep galaxy number counts and redshift distributions below the confusion limit at SPIRE wavelengths (~20 mJy), which we then use to place strong constraints on the origins of the cosmic infrared background and on models of galaxy evolution. Methods. We individually extracted the bright SPIRE sources (>20 mJy) in the COSMOS field with a method using the positions, the flux densities, and the redshifts of the 24 μm sources as a prior, and derived the number counts and redshift distributions of the bright SPIRE sources. For fainter SPIRE sources (<20 mJy), we reconstructed the number counts and the redshift distribution below the confusion limit using the deep 24 μm catalogs associated with photometric redshift and information provided by the stacking of these sources into the deep SPIRE maps of the GOODS-N and COSMOS fields. Finally, by integrating all these counts, we studied the contribution of the galaxies to the CIB as a function of their flux density and redshift. Results. Through stacking, we managed to reconstruct the source counts per redshift slice down to ~2 mJy in the three SPIRE bands, which lies about a factor 10 below the 5σ confusion limit. Our measurements place tight constraints on source population models. None of the pre-existing models are able to reproduce our results at better than 3-σ. Finally, we extrapolate our counts to zero flux density in order to derive an estimate of the total contribution of galaxies to the CIB, finding 10.1-2.3+2.6 nW m-2 sr-1, 6.5-1.6+1.7 nW m-2 sr-1, and 2.8-0.8+0.9 nW m-2 sr-1 at 250 μm, 350 μm, and 500 μm, respectively. These values agree well with FIRAS absolute measurements, suggesting our number counts and their extrapolation are sufficient to explain the CIB. We find that half of the CIB is emitted at z = 1.04, 1.20, and 1.25, respectively. Finally, combining our results with other works, we estimate the energy budget contained in the CIB between 8 μm and 1000 μm: 26-3+7 nW m-2 sr-1.
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Dates and versions

cea-00840110 , version 1 (20-10-2022)



M. Béthermin, E. Le Floc'H, O. Ilbert, A. Conley, Guilaine Lagache, et al.. HerMES: deep number counts at 250 μm, 350 μm and 500 μm in the COSMOS and GOODS-N fields and the build-up of the cosmic infrared background. Astronomy and Astrophysics - A&A, 2012, 542, pp.A58. ⟨10.1051/0004-6361/201118698⟩. ⟨cea-00840110⟩
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