Infrared Galaxies at IAS, Orsay

The Cosmic Infrared Background
Resolving the Cosmic Far-Infrared Background The Cosmic Far Infrared Background has been measured by Puget et al, 1996 for the first time, and confirmed by Hauser et al., 1998 (see e.g Hauser and Dwek, 2001 for a review). The CIB is the relic emission at IR wavelengths of galaxy formation and evolution. Studying the extragalactic backgrounds (also known as the EBL, Extragalactic Background Light) is one of the observational challenges of today's cosmology.
Buildup of the Cosmic Far-Infrared Background since redshift 2 (2011) Spitzer observations in GOODS and COSMOS fields allowed Jauzac et al., 2011 AandA (in press, or ArXiv1009.0419) to reconstruct the buildup of the CIB at 70 and 160 microns since redshift 2. Download here the text file or IDL save file of the d(nuBnu)/dz vs z shown in figure 9.
CIB brighteness from Spitzer legacy number counts (2010) The Spitzer observations at 24 microns resolves 80% of the CIB at this wavelength. We estimate the total CIB brighteness from our legacy counts (Bethermin et al., 2010a, AandA). We extrapolate the faint-end slope of the counts to estimate the contribution of non-detected populations. At 70 and 160, the confusion limits the depth of Spitzer observations. We use a stacking analysis with 24 microns as a prior to produce deep counts. We then obtain an estimation of the CIB brighteness from these counts. Contribution of sources brighter than Scut to the CIB at 24, 70 and 160 microns (from Bethermin, Dole, Beelen and Aussel, 2010, AandA). A new SED of the EBL has been derived (see below). Download the CIB contributions as a function of flux density Scut on Spitzer source counts web page
Stacking 24um sources to estimate the Cosmic Far-Infrared Background (2006) Dole et al (2006, AandA, 451, 417) resolved the Cosmic IR Background in the Far-Infrared, and compiled the latest observations of the Extragalactic Background Light (EBL), in particular for the Cosmic Optical Background (COB) and the Cosmic Infrared Background (CIB). Load H. Dole's presentation (June 2006) explaining how Spitzer resolved the CIB. You can use these slides without permission as long as you cite the authors and references. [PDF][ppt] You can also read the joint US and French April 2006 Press Release (NASA/SSC and CNRS/INSU). Image of the stacked CIB with MIPS, for about 1800 sources around S24 120uJy. From left to right: 24um, 70um, and 160um. (Dole et al., 2006)
CIB Spectral Energy Distribution (SED) (update 2009) The EBL (Extragalactic Background Light) SED is now well constrained. You can use this IDL script to generate the plot of the CIB SED with the latest observational constraints, as of January 2007. You can also download an ascii table containing the CIB strict lower limits or the CIB best guess. 2009 Spectral energy distribution of the COB (left bump) and the CIB (rigth bump). Our strict lower limit are plotted in red. Our total extrapolated CIB brighteness is plotted in blue (from Bethermin, Dole, Beelen and Aussel, 2009, submitted to AandA). Plot of the CIB and COB, as generated by the IDL script. Use the ps option. (Dole et al., 2006) Plot of the CMB, CIB and COB. Their brightnesses (in nW/m2/sr) are written in the boxes.(Dole et al., 2006)
Lower Limit EBL: data and model (2010) Kneiske and Dole (2008,2010 AandA) compiled EBL data to derive a lower limit SED, and modeled the EBL. You can download the EBL lower limit data as well as the model output.
- http://www.ias.u-psud.fr/irgalaxies - Groupe Matière Interstellaire et Cosmologie Institut d'Astrophysique Spatiale (IAS), bat 121, F-91405 Orsay Cedex, France. Université Paris Sud 11 and CNRS (UMR 8617)