Abstract / Description of output
We present a new, robust measurement of the evolving rest-frame
ultraviolet (UV) galaxy luminosity function (LF) over the key redshift
range from z ≃ 2 to z ≃ 4. Our results are based on the high
dynamic range provided by combining the Hubble Ultra Deep Field (HUDF),
CANDELS/GOODS-South, and UltraVISTA/COSMOS surveys. We utilize the
unparalleled multifrequency photometry available in this survey `wedding
cake' to compile complete galaxy samples at z ≃ 2, 3, 4 via
photometric redshifts (calibrated against the latest spectroscopy)
rather than colour-colour selection, and to determine accurate
rest-frame UV absolute magnitudes (M1500) from spectral
energy distribution (SED) fitting. Our new determinations of the UV LF
extend from M1500 ≃ -22 (AB mag) down to
M1500 = -14.5, -15.5 and -16 at z ≃ 2, 3 and 4,
respectively (thus, reaching ≃ 3-4 mag fainter than previous
blank-field studies at z ≃ 2,3). At z ≃ 2, 3, we find a much
shallower faint-end slope (α = -1.32 ± 0.03) than reported
in some previous studies (α ≃ -1.7), and demonstrate that
this new measurement is robust. By z ≃ 4, the faint-end slope has
steepened slightly, to α = -1.43 ± 0.04, and we show that
these measurements are consistent with the overall evolutionary trend
from z = 0 to 8. Finally, we find that while characteristic number
density (φ*) drops from z ≃ 2 to z ≃ 4, characteristic
luminosity (M*) brightens by ≃ 1 mag. This, combined with the new
flatter faint-end slopes, has the consequence that UV luminosity density
(and hence unobscured star formation density) peaks at z ≃ 2.5-3,
when the Universe was ≃ 2.5 Gyr old.
Original language | English |
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Pages (from-to) | 3194-3211 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 456 |
Issue number | 3 |
Early online date | 5 Jan 2016 |
DOIs | |
Publication status | Published - 1 Mar 2016 |
Keywords / Materials (for Non-textual outputs)
- galaxies: evolution
- galaxies: luminosity function
- mass function
- galaxies: photometry
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James Dunlop
- School of Physics and Astronomy - Professor of Extragalactic Astronomy and Head of School
Person: Academic: Research Active