Bibcode
Béthermin, M.; Le Floc'h, E.; Ilbert, O.; Conley, A.; Lagache, G.; Amblard, A.; Arumugam, V.; Aussel, H.; Berta, S.; Bock, J.; Boselli, A.; Buat, V.; Casey, C. M.; Castro-Rodríguez, N.; Cava, A.; Clements, D. L.; Cooray, A.; Dowell, C. D.; Eales, S.; Farrah, D.; Franceschini, A.; Glenn, J.; Griffin, M.; Hatziminaoglou, E.; Heinis, S.; Ibar, E.; Ivison, R. J.; Kartaltepe, J. S.; Levenson, L.; Magdis, G.; Marchetti, L.; Marsden, G.; Nguyen, H. T.; O'Halloran, B.; Oliver, S. J.; Omont, A.; Page, M. J.; Panuzzo, P.; Papageorgiou, A.; Pearson, C. P.; Pérez-Fournon, I.; Pohlen, M.; Rigopoulou, D.; Roseboom, I. G.; Rowan-Robinson, M.; Salvato, M.; Schulz, B.; Scott, D.; Seymour, N.; Shupe, D. L.; Smith, A. J.; Symeonidis, M.; Trichas, M.; Tugwell, K. E.; Vaccari, M.; Valtchanov, I.; Vieira, J. D.; Viero, M.; Wang, L.; Xu, C. K.; Zemcov, M.
Bibliographical reference
Astronomy and Astrophysics, Volume 542, id.A58
Advertised on:
6
2012
Journal
Citations
175
Refereed citations
168
Description
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.
Related projects
Formation and Evolution of Galaxies: Observations in Infrared and other Wavelengths
This IAC research group carries out several extragalactic projects in different spectral ranges, using space as well as ground-based telescopes, to study the cosmological evolution of galaxies and the origin of nuclear activity in active galaxies. The group is a member of the international consortium which built the SPIRE instrument for the
Ismael
Pérez Fournon