English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

(Abridged) We present here the second half of an ESO Large Programme, whichexploits the unique combination of area and sensitivity provided in the near-IRby the camera Hawk-I at the VLT. We have obtained - 30 observing hours withHawk-I in the Y-band of two high galactic latitude fields. We combined theY-band data with deep J and K Hawk-I observations, and with FORS1/FORS2 U, B,V, R, I, and Z observations to select z-drop galaxies having Z - Y > 1, nooptical detection and flat Y - J and Y - K colour terms. We detect 8high-quality candidates in the magnitude range Y = 25.5 - 26.5 that we add tothe z-drop candidates selected in two Hawk-I pointings over the GOODS-Southfield. We use this full sample of 15 objects found in -161 arcmin^2 of oursurvey to constrain the average physical properties and the evolution of thenumber density of z ~ 7 LBGs. A stacking analysis yields a best-fit SED withphotometric redshift z= 6.85 +0.20 -0.15 and an E(B-V)=0.05 +0.15 -0.05. Wecompute a binned estimate of the z ~ 7 LF and explore the effects ofphotometric scatter and model uncertainties on the statistical constraints.After accounting for the expected incompleteness through MonteCarlosimulations, we strengthen our previous finding that a Schechter luminosityfunction constant from z=6 to z=7 is ruled out at a >99% confidence level, evenincluding the effects of cosmic variance. For galaxies brighter than M_1500=-19.0, we derive a luminosity density rho_UV = 1.5^{+2.1}{-0.8} x 10^25erg/s/Hz/Mpc^3, implying a decrease by a factor 3.5 from z=6 to z=6.8. We findthat, under standard assumptions, the emission rate of ionizing photons comingfrom UV bright galaxies is lower by at least a factor of two than the valuerequired for reionization. Finally, we exploit deep Hawk-I J and K bandobservations to derive an upper limit on the number density of M1500<~ -22.0LBGs at z-8 (Y-dropouts).

The bright end of the z ~ 7 UV Luminosity Function from a wide and deep HAWK-I survey