On the nature and physical conditions of the luminous Lya emitter CR7 and its rest-frame UV components

Abstract

We present new HST/WFC3 observations and re-analyse VLT data to unveil the continuum, variability and rest-frame UV lines of the multiple UV clumps of the most luminous Ly$\alpha$ emitter at z=6.6, CR7. Our re-reduced, flux calibrated X-SHOOTER spectra of CR7 reveal a HeII emission line in observations obtained along the major axis of Lyman-alpha (Lya) emission with the best seeing conditions. HeII is spatially offset by +0.8'' from the peak of Lya emission, and it is found towards clump B. Our WFC3 grism spectra detects the UV continuum of CR7's clump A, yielding a power law with $\beta =-2.5_{-0.7}^{+0.6}$ and $M_{UV}=-21.87_{-0.20}^{+0.25}$. No significant variability is found for any of the UV clumps on their own, but there is tentative (~2.2$\sigma$) brightening of CR7 in F110W as a whole from 2012 to 2017. HST grism data fail to robustly detect rest-frame UV lines in any of the clumps, implying fluxes <2x10${}^{-17}$ erg s${}^{-1}$ cm${}^{-2}$ (3 $\sigma$). We perform CLOUDY modelling to constrain the metallicity and the ionising nature of CR7. CR7 seems to be actively forming stars without any clear AGN activity in clump A, consistent with a metallicity of ~0.05-0.2 Z${}_{\odot }$. Component C or an inter-clump component between B and C may host a high ionisation source. Our results highlight the need for spatially resolved information to study the formation and assembly of early galaxies.

arXiv comment22 pages, 12 figures. Accepted for publication in MNRAS. Reduced data used in the paper will be available with the final published paper in MNRAS

References in corpus (79)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• The COSMOS2015 Catalog: Exploring the 1<z<6 Universe with half a million galaxies
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• The MAPPINGS III Library of Fast Radiative Shock Models
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• 3D-HST: A wide-field grism spectroscopic survey with the Hubble Space Telescope
• The Interstellar Medium In Galaxies Seen A Billion Years After The Big Bang
• Distant Radio Galaxies and their Environments
• UV-Continuum Slopes of >4000 z~4-8 Galaxies from the HUDF/XDF, HUDF09, ERS, CANDELS-South, and CANDELS-North Fields
• A dusty, normal galaxy in the epoch of reionization
• Stellar Population Effects on the Inferred Photon Density at Reionization
• Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated Reionization Around Luminous Star Forming Systems?
• Evidence for PopIII-like stellar populations in the most luminous Lyman-$\alpha$ emitters at the epoch of re-ionisation: spectroscopic confirmation
• Spectral synthesis including massive binaries
• Dust in the reionization era: ALMA observations of a $z$=8.38 Galaxy
• Spectroscopic detection of CIV in a galaxy at z=7.045: Implications for the ionizing spectra of reionization-era galaxies
• "Big Three Dragons": a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $\mu$m, [CII] 158 $\mu$m, and Dust Continuum with ALMA
• The assembly of "normal" galaxies at z=7 probed by ALMA
• Rotation in [CII]-emitting gas in two galaxies at a redshift of 6.8
• The bright end of the galaxy luminosity function at z ~ 7: before the onset of mass quenching?
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• An Intensely Star-Forming Galaxy at z~7 with Low Dust and Metal Content Revealed by Deep ALMA and HST Observations
• Ultraviolet spectra of extreme nearby star-forming regions --- approaching a local reference sample for JWST
• Identification of the brightest Lyα emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era
• Detection of atomic carbon [CII] 158 micron and dust emission from a z=7.1 quasar host galaxy
• Unveiling the nature of bright z ~ 7 galaxies with the Hubble Space Telescope
• A critical analysis of the UV-continuum slopes of high-redshift galaxies; no evidence (yet) for extreme stellar populations at z > 6
• First Results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) Survey: Cosmological Reionization at z ~ 7
• Kiloparsec-scale gaseous clumps and star formation at $z=5-7$
• Extended ionised and clumpy gas in a normal galaxy at z=7.1 revealed by ALMA
• The VIMOS Ultra Deep Survey: Nature, ISM properties, and ionizing spectra of CIII]1909 emitters at z=2-4
• The Slitless Spectroscopy Data Extraction Software aXe
• Properties of $z\sim 3-6$ Lyman Break Galaxies. II. Impact of nebular emission at high redshift
• SILVERRUSH. III. Deep Optical and Near-Infrared Spectroscopy for Lya and UV-Nebular Lines of Bright Lya Emitters at z=6-7
• GOLDRUSH. II. Clustering of Galaxies at $z\sim 4-6$ Revealed with the Half-Million Dropouts Over the 100 deg${}^2$ Area Corresponding to 1 Gpc${}^3$
• Zooming on the internal structure of $z\simeq 6$ galaxies
• Dusty galaxies in the Epoch of Reionization: simulations
• SILVERRUSH. V. Census of Lya, [OIII]5007, Ha, and [CII]158um Line Emission with ~1000 LAEs at z=4.9-7.0 Revealed with Subaru/HSC
• Slicing COSMOS with SC4K: the evolution of typical Lya emitters and the Lya escape fraction from z~2 to z~6
• A spectroscopic search for AGN activity in the reionization era
• The Lyman-alpha luminosity function at z=5.7-6.6 and the steep drop of the faint end: implications for reionization
• ALMA Observation of 158 micron [CII] Line and Dust Continuum of a z=7 Normally Star-forming Galaxy in the Epoch of Reionization
• Photoionization Models for the Semi-Forbidden C III] 1909 Emission in Star-Forming Galaxies
• ALMA reveals metals yet no dust within multiple components in CR7
• Dissecting the IRX - $\beta$ dust attenuation relation: exploring the physical origin of observed variations in galaxies
• The nature of luminous Lyman-alpha emitters at z~2-3: maximal dust-poor starbursts and highly ionising AGN
• New constraints on dust emission and UV attenuation of z=6.5-7.5 galaxies from millimeter observations
• ALMA suggests outflows in z~5.5 galaxies
• Discovery of bright z ~ 7 galaxies in the UltraVISTA survey
• Spectroscopic properties of luminous Lyman-α emitters at $z\approx 6-7$ and comparison to the Lyman-break population
• ALMA detection of extended [CII] emission in Himiko at z=6.6
• An Ultraluminous Lyman Alpha Emitter with a Blue Wing at z=6.6
• Quantifying the UV continuum slopes of galaxies to z~10 using deep Hubble and Spitzer/IRAC observations
• No evidence for Population III stars or a Direct Collapse Black Hole in the z = 6.6 Lyman-$\alpha$ emitter 'CR7'
• Modeling $237$ Lyman-$\alpha$ spectra of the MUSE-Wide survey
• The Brightest Ly$\alpha$ Emitter: Pop III or Black Hole?
• Dynamical Characterization of Galaxies at z~4-6 via Tilted Ring Fitting to ALMA [CII] Observations
• Detecting Direct Collapse Black Holes: making the case for CR7
• First results from Faint Infrared Grism Survey (FIGS): first simultaneous detection of Lyman-alpha emission and Lyman break from a galaxy at z=7.51
• Lyman Alpha Signatures from Direct Collapse Black Holes
• Evidence for a direct collapse black hole in the Lyman-alpha source CR7
• Exploring the nature of the Lyman-$\alpha$ emitter CR7
• First Spectroscopic Confirmations of z ~ 7.0 Lya Emitting Galaxies in the LAGER Survey
• Ly-alpha emitters in the GOODS-S field: a powerful pure nebular SED with N IV] emission at z=5.563
• Formation of Massive Population III Galaxies through Photoionization Feedback: A Possible Explanation for CR7
• The nature of the Lyman Alpha Emitter CR7: a persisting puzzle
• MUSE integral-field spectroscopy towards the Frontier Fields cluster Abell S1063: II. Properties of low luminosity Lyman alpha emitters at z>3
• What is the Maximum Mass of a Population III Galaxy?
• Galaxy Formation Through Filamentary Accretion at z=6.1
• Deep rest-frame far-UV spectroscopy of the giant Lyman-alpha emitter 'Himiko'
• A Magellan M2FS Spectroscopic Survey of Galaxies at 5.5<z<6.8: Program Overview and a Sample of the Brightest Lyman-alpha Emitters
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• An Active Galactic Nucleus Caught in the Act of Turning Off and On
• Metallicity evolution of direct collapse black hole hosts: CR7 as a case study
• Ionization and feedback in Ly$\alpha$ halos around two radio galaxies at z$\sim$2.5
• A bright lensed galaxy at $z=5.4$ with strong Ly$\alpha$ emission

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