A critical analysis of the UV Luminosity Function at redshift~7 from deep WFC3 data

Abstract

The study of the Luminosity Function (LF) of Lyman Break Galaxies (LBGs) at z=7 is important for ascertaining their role in the reionization of the Universe. We perform a detailed and critical analysis of the statistical and systematic errors in the z~7 LF determination: we have assembled a large sample of candidate LBGs at z~7 from different surveys, spanning a large variety of areas and depths. In particular, we have combined data from the deep (J<27.4) and ultradeep (J<29.2) surveys recently acquired with the new WFC3 NIR camera on HST, over the GOODS-ERS and the HUDF fields, with ground based surveys in wide and shallow areas from VLT and Subaru. We have used public ACS images in the z-band to select z-dropout galaxies, and other public data both in the blue (BVI) and in the red bands to reject possible low-redshift interlopers. We have compared our results with extensive simulations to quantify the observational effects of our selection criteria as well as the effects of photometric scatter, color selections or the morphology of the candidates. We have found that the number density of faint LBGs at z~7 is only marginally sensitive to the color selection adopted, but it is strongly dependent from the assumption made on the half light distributions of the simulated galaxies, used to correct the observed sample for incompleteness. The slope of the faint end of the LBGs LF has thus a rather large uncertainty, due to the unknown distribution of physical sizes of the z~7 LBGs. We conclude that galaxies at z~7 are unable to reionize the Universe unless there is a significant evolution in the clumpiness of the IGM or in the escape fraction of ionising photons or, alternatively, there is a large population of z~7 LBGs with large physical dimensions but still not detected by the present observations.

15 pages, 11 figures, accepted for publication in A&A

References in corpus (21)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• The Hubble Ultra Deep Field
• UV Luminosity Functions at z~4, 5, and 6 from the HUDF and other Deep HST ACS Fields: Evolution and Star Formation History
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• z~7-10 Galaxies in the HUDF and GOODS fields, and their UV Luminosity Functions
• The high redshift galaxy population in hierarchical galaxy formation models
• The Evolution of Lyman Limit Absorption Systems to Redshift Six
• Spectroscopic confirmation of two Lyman break galaxies at redshift beyond 7
• The lack of intense Lyman~alpha in ultradeep spectra of z=7 candidates in GOODS-S: imprint of reionization?
• The luminosity function, halo masses and stellar masses of luminous Lyman-break galaxies at redshifts 5<z<6
• The Great Observatories Origins Deep Survey: Constraints on the Lyman Continuum Escape Fraction Distribution of Lyman--Break Galaxies at 3.4<z<4.5
• LCDM predictions for galaxy protoclusters I: the relation between galaxies, protoclusters and quasars at z~6
• The UDF05 Follow-up of the HUDF: I. The Faint-End Slope of the Lyman-Break Galaxy Population at z~5
• The UDF05 Follow-up of the HUDF: II. Constraints on Reionization from z-dropout Galaxies
• Probing Very Bright End of Galaxy Luminosity Function at z >~ 7 Using Hubble Space Telescope Pure Parallel Observations
• Rapid Evolution in the Most Luminous Galaxies During the First 900 Million Years
• The bright end of the z ~ 7 UV Luminosity Function from a wide and deep HAWK-I survey
• A Spectroscopic Search for Leaking Lyman Continuum at z~0.7
• Evidence for strong evolution of the cosmic star formation density at high redshift
• A Limit on the Number Density of Bright z~7 Galaxies

Cited by in corpus (54)

• Cosmic Star Formation History
• The Average Star Formation Histories of Galaxies in Dark Matter Halos from z=0-8
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• CANDELS Multi-wavelength Catalogs: Source Detection and Photometry in the GOODS-South Field
• Spectroscopic Confirmation of Three z-Dropout Galaxies at z = 6.844 - 7.213: Demographics of Lyman-Alpha Emission in z ~ 7 Galaxies
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• Spectroscopic confirmation of z~7 LBGs: probing the earliest galaxies and the epoch of reionization
• The z~6 Luminosity Function Fainter than -15 mag from the Hubble Frontier Fields: The Impact of Magnification Uncertainties
• CANDELS: The Contribution of the Observed Galaxy Population to Cosmic Reionization
• Escape of Lyman continuum radiation from local galaxies - Detection of leakage from the young starburst Tol 1247-232
• The 2012 Hubble Ultra Deep Field (UDF12): Observational Overview
• Size--luminosity relations and UV luminosity functions at $z=6-9$ simultaneously derived from the complete Hubble Frontier Fields data
• New Constraints on the Faint-end of the UV Luminosity Function at z~7-8 using the Gravitational Lensing of the Hubble Frontier Fields Cluster A2744
• Faint high-redshift AGN in the Chandra Deep Field South: the evolution of the AGN luminosity function and black hole demography
• Evolution of the galaxy stellar mass functions and UV luminosity functions at $z=6-9$ in the Hubble Frontier Fields
• First Frontier Field Constraints on the Cosmic Star-Formation Rate Density at z~10 - The Impact of Lensing Shear on Completeness of High-Redshift Galaxy Samples
• The evolving slope of the stellar mass function at 0.6 <= z < 4.5 from deep WFC3 data
• Gas Clumping in Self-Consistent Reionisation Models
• z~2-9 Galaxies Magnified by the Hubble Frontier Field Clusters II: Luminosity Functions and Constraints on a Faint-End Turnover
• The size-luminosity relation at z=7 in CANDELS and its implication on reionization
• Expanded Search for z~10 Galaxies from HUDF09, ERS, and CANDELS Data: Evidence for Accelerated Evolution at z>8?
• Escape Fraction of Ionizing Radiation from Starburst Galaxies at High Redshifts
• The blue UV slopes of z~4 Lyman break galaxies: implications for the corrected star formation rate density
• Constraints on the star-formation rate of z~3 LBGs with measured metallicity in the CANDELS GOODS-South field
• The Evolution Of The Faint End Of The UV Luminosity Function During The Peak Epoch Of Star Formation (1<z<3)
• Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation
• Evolution in the Escape Fraction of Ionizing Photons and the Decline in Strong Lya Emission from z>6 Galaxies
• The Bivariate Size-luminosity Relations for Lyman Break Galaxies at z ~ 4 - 5
• Black hole growth in the early Universe is self-regulated and largely hidden from view
• Extremely Small Sizes for Faint z~2-8 Galaxies in the Hubble Frontier Fields: A Key Input For Establishing their Volume Density and UV Emissivity
• Probing the z>6 Universe with the first Hubble Frontier Fields cluster Abell 2744
• Fundamental physics with the Hubble Frontier Fields: constraining Dark Matter models with the abundance of extremely faint and distant galaxies
• Sizes of Lensed Lower-luminosity z=4-8 Galaxies from the Hubble Frontier Field Program
• First Light And Reionisation Epoch Simulations (FLARES) IV: The size evolution of galaxies at $z\ge 5$
• Discovery of Lyman Break Galaxies at z~7 from the ZFOURGE Survey
• Chandra counterparts of CANDELS GOODS-S sources
• The evolution of the size-mass relation at $z$=1-3 derived from the complete Hubble Frontier Fields data set
• Observing the first galaxies
• Mapping metals at high redshift with far-infrared lines
• Radiative properties of the first galaxies: rapid transition between blue and red
• AGNs as main contributors to the UV ionizing emissivity at high redshifts: predictions from a Lambda-CDM model with linked AGN/galaxy evolution
• The XMM deep survey in the CDF-S II. a 9-20 keV selection of heavily obscured active galaxies at z>1.7
• A 52 hours VLT/FORS2 spectrum of a bright z~7 HUDF galaxy: no Ly-alpha emission
• The size-luminosity relation of lensed galaxies at $z=6-9$ in the Hubble Frontier Fields
• Globular Clusters in High-Redshift Dwarf Galaxies: A Case Study from the Local Group
• The Evolution of Active Galactic Nuclei in Warm Dark Matter Cosmology
• Universe opacity and CMB
• A Search for z=7.3 Lyα Emitters behind Gravitationally Lensing Clusters
• The Star-Forming Interstellar Medium of Lyman Break Galaxy Analogs
• Semi-Numerical Simulation of Reionization with Semi-Analytical Modeling of Galaxy Formation
• RELICS: Small Lensed $z\ge 5.5$ Galaxies Selected as Potential Lyman Continuum Leakers
• Observing the very low-surface brightness dwarfs in a deep field in the VIRGO cluster: constraints on Dark Matter scenarios
• The impact of black hole feedback on the UV luminosity and stellar mass assembly of high-redshift galaxies