LUNDI 12 mai 2003, à 14h, 77 avenue Denfert Rochereau
77 avenue Denfert Rochereau, Paris 14
Salle de l'Atelier, Observatoire de Paris
Feedback to the Rescue of Galaxy Formation in CDM Cosmology
Avishai DEKEL
The Hebrew University of Jerusalem
Résumé :
Galaxy formation theory within the CDM paradigm faces several difficulties
such as the cusp/core discrepancy, the angular-momentum loss, and the
missing dwarfs. These problems are modeled in simple terms within the
merger picture and a common solution is proposed: feedback effects from
supernovae and background radiation. In particular, new data from SDSS
and the Local Group refine the scaling relations obeyed by LSB/dwarf
galaxies over a range of 5 decades in stellar mass (representing 95\%
of the galaxies). A simple model of supernova feedback naturally
recovers these relations
and explains the distinction between LSB and bright galaxies, indicating
that the feedback effects have a primary role in determining the galaxy
properties along the LSB sequence. Radiative feedback is more effective
than previously thought -- it may explain dark mini-haloes with no
luminous component and the distinction between dwarf spheroidals
and irregulars.
