The evolving faint end of the luminosity function

S. Khochfar, J. Silk, Rogier Windhorst, R. E. Ryan

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

We investigate the evolution of the faint-end slope of the luminosity function, α, using semianalytical modeling of galaxy formation. In agreement with observations, we find that the slope can be fitted well by α(z) = a + bza, with a = -1.13 and b = -0.1. The main driver for the evolution in α is the evolution in the underlying dark matter mass function. Sub-L * galaxies reside in dark matter halos that occupy a different part of the mass function. This part of the mass function is steeper at high redshifts than at low redshifts, and hence α is steeper. Supernova feedback in general causes the same relative flattening with respect to the dark matter mass function. The faint-end slope at low redshifts is dominated by field galaxies, and at high redshifts by cluster galaxies. The evolution of α(z) in each of these environments is different, with field galaxies having a slope b = -0.14 and cluster galaxies having a slope b. The transition from a cluster-dominated to a field-dominated faintend slope occurs roughly at a redshift z*, ∼ 2 and suggests that a single linear fit to the overall evolution of α(z) might not be appropriate. Furthermore, this result indicates that tidal disruption of dwarf galaxies in clusters cannot play a significant role in explaining the evolution of α(z) at z <z *. In addition, we find that different star formation efficiencies α* in the Schmidt-Kennicutt law and supernova-feedback efficiencies ξ generally do not strongly influence the evolution of. α(z).

Original languageEnglish (US)
JournalAstrophysical Journal
Volume668
Issue number2 PART 2
DOIs
StatePublished - 2007

Fingerprint

luminosity
slopes
galaxies
dark matter
supernovae
galactic evolution
flattening
dwarf galaxies
star formation
halos
causes
modeling

Keywords

  • Galaxies: evolution
  • Methods: numerical

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

The evolving faint end of the luminosity function. / Khochfar, S.; Silk, J.; Windhorst, Rogier; Ryan, R. E.

In: Astrophysical Journal, Vol. 668, No. 2 PART 2, 2007.

Research output: Contribution to journalArticle

Khochfar, S. ; Silk, J. ; Windhorst, Rogier ; Ryan, R. E. / The evolving faint end of the luminosity function. In: Astrophysical Journal. 2007 ; Vol. 668, No. 2 PART 2.
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