Two-phase galaxy formation: the evolutionary properties of galaxies

Authors

  • M. Cook,

    Corresponding author
    1. Astrophysics Sector, SISSA/ISAS, Via Beirut 2-4, I-34014 Trieste, Italy
    2. INAF, Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova, Italy
    Search for more papers by this author
  • E. Barausse,

    1. Astrophysics Sector, SISSA/ISAS, Via Beirut 2-4, I-34014 Trieste, Italy
    2. Centre for Fundamental Physics, University of Maryland, College Park, MD 20742-4111, USA
    Search for more papers by this author
  • C. Evoli,

    1. Astrophysics Sector, SISSA/ISAS, Via Beirut 2-4, I-34014 Trieste, Italy
    Search for more papers by this author
  • A. Lapi,

    1. Astrophysics Sector, SISSA/ISAS, Via Beirut 2-4, I-34014 Trieste, Italy
    2. Department of Physics, Univ. di Roma ‘Tor Vergata’, Via della Ricerca Scientifica 1, I-00133 Rome, Italy
    3. INAF, Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste, Italy
    Search for more papers by this author
  • G. L. Granato

    1. INAF, Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova, Italy
    2. INAF, Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste, Italy
    Search for more papers by this author

E-mail: cook@sissa.it

ABSTRACT

We use our model for the formation and evolution of galaxies within a two-phase galaxy formation scenario, showing that the high-redshift domain typically supports the growth of spheroidal systems, whereas at low redshifts the predominant baryonic growth mechanism is quiescent and may therefore support the growth of a disc structure. Under this framework, we investigate the evolving galaxy population by comparing key observations at both low and high redshifts, finding generally good agreement. By analysing the evolutionary properties of this model, we are able to recreate several features of the evolving galaxy population with redshift, naturally reproducing number counts of massive star-forming galaxies at high redshifts, along with the galaxy scaling relations, star formation rate density and evolution of the stellar mass function. Building upon these encouraging agreements, we make model predictions that can be tested by future observations. In particular, we present the expected evolution to z= 2 of the supermassive black hole mass function, and we show that the gas fraction in galaxies should decrease with increasing redshift in a mass, with more and more evolution going to higher and higher masses. Also, the characteristic transition mass from a disc to bulge-dominated system should decrease with increasing redshift.

Ancillary