Luminous Lyman Break Galaxies at z>5 and the Source of Reionization

Abstract

We have discovered six galaxies with spectroscopically confirmed redshifts of 4.8<z<5.8 in a single 44 square arcminute field imaged deeply in R, I and z-bands. All the spectra show an emission-line in the region around 7000-8400 angstroms with a spectroscopically-detected faint continuum break across the line. These six were drawn from 13 sources with I_AB<26.2 and R_AB-I_AB>1.5 in the field, this photometric cut designed to select galaxies at z>4.8. The line fluxes range between 0.2 to 2.5 x 10^-17 ergs cm^-2 s^-1 indicating luminosities of around 10^42-43 ergs s^-1 for Ly-alpha and their high emission line equivalent widths suggest very young ages (<10^8 yrs). A further line-emitting object with no detectable continuum was serendipitously detected by spectroscopy. If this line is Ly-alpha then it is from a source at z=6.6, making this the most distant galaxy known. However, the redshift cannot be considered secure as it is based on a single line. No broad emission line objects (quasars) were detected. The 13 sources at I_AB<26.2 are less than that expected if the luminosity function of dropout galaxies remained unchanged between z=3 and z=6, although the deficit is not highly significant given possible cosmic variance. The UV luminosity density from galaxies brighter than our flux limit is considerably less than that necessary to keep the volume probed by our field at <z>~5.3 ionized. These galaxies are observed within several hundred Myr of the end of the epoch of reionization (z=6-7), with little time for the luminosity function to evolve. This, and the lack of detected quasars, imply that the bulk of the UV flux that reionized the universe came from faint galaxies with M_(1700 ang)>-21.

24 pages (latex, aas macros), 7 figures (12 postscript files), accepted for publication in the Astrophysical Main Journal

References in corpus (2)

• Spectroscopic Confirmation of Three Redshift 5.7 Lyman-alpha Emitters from the Large Area Lyman Alpha Survey
• Lyman Break Galaxies and the Star Formation Rate of the Universe at z~6

Cited by in corpus (98)

• The epochs of early-type galaxy formation as a function of environment
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• A Redshift Survey of the Submillimeter Galaxy Population
• UV Luminosity Functions at z~4, 5, and 6 from the HUDF and other Deep HST ACS Fields: Evolution and Star Formation History
• The Subaru/XMM-Newton Deep Survey (SXDS). IV. Evolution of Lya Emitters from z=3.1 to 5.7 in the 1 deg^2 Field: Luminosity Functions and AGN
• UV-continuum slopes at z~4-7 from the HUDF09+ERS+CANDELS observations: Discovery of a well-defined UV-color magnitude relationship for z>=4 star-forming galaxies
• UV Continuum Slope and Dust Obscuration from z~6 to z~2: The Star Formation Rate Density at High Redshift
• Multi-Wavelength Constraints on the Cosmic Star Formation History from Spectroscopy: the Rest-Frame UV, H-alpha, and Infrared Luminosity Functions at Redshifts 1.9<z<3.4
• The Rest-Frame UV Luminosity Density of Star-Forming Galaxies at Redshifts z>3.5
• The Universe is Reionizing at z~7: Bayesian Inference of the IGM Neutral Fraction Using Ly$\alpha$ Emission from Galaxies
• 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
• Galaxies at z~6: The UV Luminosity Function and Luminosity Density from 506 UDF, UDF-Ps, and GOODS i-dropouts
• A Deep, Wide Field, Optical, and Near Infrared Catalog of a Large Area around the Hubble Deep Field North
• CANDELS: The Evolution of Galaxy Rest-Frame Ultraviolet Colors from z = 8 to 4
• Spectroscopic confirmation of z~7 LBGs: probing the earliest galaxies and the epoch of reionization
• z~7-10 Galaxies in the HUDF and GOODS fields, and their UV Luminosity Functions
• The Stellar Mass Density and Specific Star Formation Rate of the Universe at z~7
• Keeping the Universe ionised: Photo-heating and the clumping factor of the high-redshift intergalactic medium
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Very blue UV-continuum slopes of low luminosity z~7 galaxies from WFC3/IR: Evidence for extremely low metallicities?
• Color-selected galaxies at z~6 in the Great Observatories Origins Deep Survey
• The Luminosity Function of Lyman Alpha Emitters at Redshift z~5.7
• Subaru high-z exploration of low-luminosity quasars (SHELLQs). I. Discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9
• Spectroscopic confirmation of two Lyman break galaxies at redshift beyond 7
• CARS: The CFHTLS-Archive-Research Survey II. Weighing dark matter halos of Lyman-break galaxies at z=3-5
• Spitzer IRAC confirmation of z_850-dropout galaxies in the Hubble Ultra Deep Field: stellar masses and ages at z~7
• The Reionization and Galaxy Evolution Probed by z=7 Lyman Alpha Emitters
• Ultradeep Infrared Array Camera Observations of sub-L* z~7 and z~8 Galaxies in the Hubble Ultra Deep Field: the Contribution of Low-Luminosity Galaxies to the Stellar Mass Density and Reionization
• Keck Deep Fields. II. The UV Galaxy Luminosity Function at z~4, 3, and 2
• Spectroscopic Properties of the z=4.5 Lyman-alpha Emitters
• Discovery of a Very Bright Strongly-Lensed Galaxy Candidate at z ~ 7.6
• HST imaging and Keck Spectroscopy of z~6 I-band Drop-Out Galaxies in the ACS GOODS Fields
• The C IV Mass Density of the Universe at Redshift 5
• A Luminosity Function of Lyman Alpha Emitting Galaxies at Redshift 4.5
• The Abundance of Low-luminosity Lyman alpha Emitters at High Redshift
• Lyman-break galaxies at z~5 -I. First significant stellar mass assembly in galaxies that are not simply z~3 LBGs at higher redshift
• Deficiency of large equivalent width Lyman-alpha emission in luminous Lyman break galaxies at z~5-6?
• Star Formation at z~6: i-dropouts in the ACS GTO fields
• The Obelisk simulation: galaxies contribute more than AGN to HI reionization of protoclusters
• Three Lyman-alpha Emitters at z approx 6: Early GMOS/Gemini Data from the GLARE Project
• No Evidence for Lyman-alpha Emission in Spectroscopy of z > 7 Candidate Galaxies
• The UDF05 Follow-up of the HUDF: II. Constraints on Reionization from z-dropout Galaxies
• Clustering of Star-forming Galaxies Near a Radio Galaxy at z=5.2
• The Major Sources of the Cosmic Reionizing Background at z ~ 6
• A VLT/FORS2 view at $z\sim 6$: Lyman-$\alpha$ emitter fraction and galaxy physical properties at the edge of the epoch of cosmic reionization
• The bright end of the z ~ 7 UV Luminosity Function from a wide and deep HAWK-I survey
• Differential Evolution of the UV Luminosity Function of Lyman Break Galaxies from z~5 to 3
• z~7-10 Galaxies behind Lensing Clusters: Contrast with Field Search Results
• The FORS Deep Field Spectroscopic Survey
• The Stellar Populations of Lyman Break Galaxies at z~5
• The GLARE Survey II. Faint z=6 Ly-alpha Line Emitters in the HUDF
• Spectroscopy of z~6 i-dropout Galaxies: Frequency of Ly-alpha Emission and the Sizes of Ly-alpha Emitting Galaxies
• Are z~5 QSOs found in the most massive high redshift over-densities?
• Probing $\sim L_{\ast }$ Lyman-break Galaxies at $z\approx 7$ in GOODS-South with WFC3 on HST
• Quantifying the UV continuum slopes of galaxies to z~10 using deep Hubble and Spitzer/IRAC observations
• Keck Deep Fields. III. Luminosity-dependent Evolution of the Ultraviolet Luminosity and Star Formation Rate Densities at z~4, 3, and 2
• The Effect of Galactic Properties on the Escape Fraction of Ionizing Photons
• The faint afterglow and host galaxy of the short-hard GRB 060121
• Spectroscopic investigation of a reionized galaxy overdensity at z=7
• A large population of galaxies 9 to 12 billion years back in the history of the Universe
• Lyman Break Galaxies at $z\sim 5$: Rest-Frame UV Spectra
• Observing the first galaxies
• High-redshift galaxies and low-mass stars
• The Space Density of Redshift 5.7 Ly-Alpha Emitters
• A gravitationally-boosted MUSE survey for emission-line galaxies at z>~5 behind the massive cluster RCS 0224
• On Contamination and Completeness in z>5 Lyman Break Galaxy Surveys
• Star Formation and AGN activity in Galaxies classified using the 1.6 μm Bump and PAH features at $z=0.4-2$
• Lyman Break Galaxies at z~5: Rest-frame UV Spectra II
• The Properties of Galaxies at z>5
• A VLT/FORS2 Multi-Slit Search for Lyman-alpha Emitting Galaxies at z~6.5
• Spectroscopy of z~5 Lyman Break Galaxies in the ESO Remote Galaxy Survey
• Lyman-alpha emission galaxies at a redshift of z = 5.7 in the FORS Deep Field
• Detections of Faint Lyman-alpha Emitters at z = 5.7: Galaxy Building Blocks and Engines of Reionization
• What do observations of the Lyman-alpha fraction tell us about reionization?
• A Limit on the Number Density of Bright z~7 Galaxies
• Surface Brightness Evolution of Galaxies in the CANDELS GOODS Fields up to $z\sim 6$: High-z Galaxies are Unique or Remain Undetected
• The Size and Pervasiveness of Ly$\alpha$-UV Spatial Offsets in Star-Forming Galaxies at $z\sim 6$
• Gemini H-band imaging of the field of a z=10 candidate
• GALEX selected Lyman Break Galaxies at z~2: Comparison with other Populations
• Mid-Infrared Spectroscopy of Two Lensed Star-forming Galaxies
• Photometric Selection of z~5 Lyman Break Galaxies in the ESO Remote Galaxy Survey
• Have we detected one of the sources responsible for an early reionisation of the Universe?
• Photometric Properties of the Most Massive High-Redshift Galaxies
• Discovery of a single faint AGN in a large sample of z>5 Lyman break galaxies
• M-Dwarfs at Large Heliocentric Distances
• Spectroscopy and Stellar Populations of Star-forming Galaxies at z~3 in the Hubble Deep Field - South
• Limits on the Molecular Gas Content of z-5 LBGs
• Discovery of a faint R-band drop-out: a strongly reddened lensed star forming galaxy at z=1.68
• Lyman Break Galaxies and Reionization of the Universe
• The Deep Optical Imaging of the Extended Groth Strip
• A Compact Starburst Core in the Dusty Lyman Break Galaxy Westphal-MD11
• Lyman break and UV-selected galaxies at $z\sim 1$ I. Stellar populations from ALHAMBRA survey
• Deep VLT V-band Imaging of the Field of a z=10 Candidate Galaxy: Below the Lyman Limit?
• Lyman Break Galaxies at z~5: Rest-Frame UV Spectra. III
• Identifying clustering at high redshift through actively star-forming galaxies
• ELTs Adaptive Optics for Multi-Objects 3D Spectroscopy : Key Parameters and Design Rules
• Faint Galaxy Number Counts in the Durhamand SDSS Catalogues
• The Most Distant Galaxies