Characterizing the evolving K -band luminosity function using the UltraVISTA, CANDELS and HUDF surveys

Journal article

We present the results of a new study of the K-band galaxy luminosity function (KLF) at redshifts z ≤ 3.75, based on a nested combination of the UltraVISTA, Cosmic Assembly Nearinfrared Deep Legacy Extragalactic Survey and HUDF surveys. The large dynamic range in luminosity spanned by this new data set (3-4 dex over the full redshift range) is sufficient to clearly demonstrate for the first time that the faint-end slope of the KLF at z ≥ 0.25 is relatively steep (-1.3 ≤ α ≤ -1.5 for a single Schechter function), in good agreement with recent theoretical and phenomenological models. Moreover, based on our new data set, we find that a double Schechter function provides a significantly improved description of the KLF at z ≤ 2. At redshifts z ≥ 0.25, the evolution of the KLF is remarkably smooth, with little or no evolution evident at faint (MK* ≥-20.5) or bright magnitudes (MK* ≤-24.5). Instead, the KLF is seen to evolve rapidly at intermediatemagnitudes, with the number density of galaxies at MK* ≃-23 dropping by a factor of ≃5 over the redshift interval 0.25 ≤ z ≥ 3.75. Motivated by this, we explore a simple description of the evolving KLF based on a double Schechter function with fixed faint-end slopes (α1= -0.5, α2= -1.5) and a shared characteristic magnitude (MK*). According to this parametrization, the normalization of the component which dominates the faint end of the KLF remains approximately constant, with φ2decreasing by only a factor of ≃2 between z ≃0 and 3.25. In contrast, the component which dominates the bright end of the KLF at low redshifts evolves dramatically, becoming essentially negligible by z ≃3. Finally, we note that within this parametrization, the observed evolution of MK*between z ≃0 and 3.25 is entirely consistent with MK*corresponding to a constant stellar mass of M≃5 × 1010 M⊙at all redshifts.

Authors: Mortlock, A; McLure, R; Bowler, R; McLeod, D; Mármol-Queraltó, E

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 465
• Issue: 1
• Pages: 672-687
• Publication date: 2016-10-23
• Acceptance date: 2016-10-18
• DOI: 10.1093/mnras/stw2728
• EISSN: 1365-2966
• ISSN: 0035-8711
• Keywords: galaxies: general; galaxies: evolution; galaxies: formation; galaxies: luminosity function, mass function