Galaxies and their Evolution

How do the galaxies form and evolve ?
What are the physical processes driving the evolution ?

Since the late 90’s, it became clear that infrared galaxies (because they emit more than 95% of their energy in the infrared, ranging from 3 microns to 1 mm wavelength) play a critical role in the formation and evolution of galaxies. They are as much rare in the Local Universe as they are frequent at high redshift. We are working on infrared galaxies since the discovery by our team of the Cosmic Infrared Background in 1996. This research field is rapidly evolving, thanks to the new Spitzer data, and will continue to evolve with forthcoming data from the Herschel and Planck satellites. At the IAS, our main activities deal with:

• The nature of infrared galaxies

  • Individual Aspects

    • Luminosity, Spectral Energy Distributions

    • Energy Sources : Star Formation and/or Active Galactic Nuclei

    • Dust content

    • Stellar Content

  • Statistical Aspects

    • Evolution in Number and Luminosity

      • Source Counts

      • Luminosity Functions

    • Spatial Correlations

    • Biais with Dark Matter Distribution

• Characterization of the Cosmic Infrared Background:

  • Spectral Energy Distribution

  • Spatial Distribution

  • Nature of Galaxies contributing to the CIB at various wavelengths

Our analyses are based on:

• Deep Infrared Surveys conducted from Space

• Multi-wavelength Follow-up Observations (visible to radio) of these Deep Fields

• Modelling of IR Galaxies Evolution

• Knowledge of the Interstellar Medium of our Galaxy and of Local Galaxies (observations and models)

• Deep knowledge of space instruments we are using, thanks to our direct participation to their development : ground and flight calibration, characterization of the detector behavior.

Involved scientists are:

    Nicolas Bavouzet (Doctorant)
    Alexandre Beelen (Post-doctorant)
    François Boulanger (Directeur de Recherche)   
    Hervé Dole (Maître de Conférences)
    Nestor Férnandez-Conde (Doctorant)
    Guilaine Lagache (Astronome Adjointe)
    Delphine Marcillac (Post-doctorante)
    Nicolas Ponthieu (Chargé de Recherche)
    Jean-Loup Puget (Directeur de Recherche)

ancien membres de l'équipe:

    Karina Caputi

The COsmic Infrared Background resolved by Spitzer. 

Stacking ~1800 faint galaxies seen at 24um (left, blue) allows Dole and his team to securely detect "invisible" galaxies at 70um (middle, green) and 160um (right, red) which are not detected individually. This strong signal (center of the two right panels) is the signature of galaxies accounting for most of the cosmic infrared background. Dole et al., 2006.
Read the Press Release 2006 NASA/CNRS.

One of the first Spitzer images in the infrared, showing galaxies.
Read the 2004 Press Release.