Euclid preparation. XXI. Intermediate-redshift contaminants in the search for $z>6$ galaxies within the Euclid Deep Survey

Abstract

(Abridged) The Euclid mission is expected to discover thousands of z>6 galaxies in three Deep Fields, which together will cover a ~40 deg2 area. However, the limited number of Euclid bands and availability of ancillary data could make the identification of z>6 galaxies challenging. In this work, we assess the degree of contamination by intermediate-redshift galaxies (z=1-5.8) expected for z>6 galaxies within the Euclid Deep Survey. This study is based on ~176,000 real galaxies at z=1-8 in a ~0.7 deg2 area selected from the UltraVISTA ultra-deep survey, and ~96,000 mock galaxies with 25.3$\le$H<27.0, which altogether cover the range of magnitudes to be probed in the Euclid Deep Survey. We simulate Euclid and ancillary photometry from the fiducial, 28-band photometry, and fit spectral energy distributions (SEDs) to various combinations of these simulated data. Our study demonstrates that identifying z>6 with Euclid data alone will be very effective, with a z>6 recovery of 91(88)% for bright (faint) galaxies. For the UltraVISTA-like bright sample, the percentage of z=1-5.8 contaminants amongst apparent z>6 galaxies as observed with Euclid alone is 18%, which is reduced to 4(13)% by including ultra-deep Rubin (Spitzer) photometry. Conversely, for the faint mock sample, the contamination fraction with Euclid alone is considerably higher at 39%, and minimized to 7% when including ultra-deep Rubin data. For UltraVISTA-like bright galaxies, we find that Euclid (I-Y)>2.8 and (Y-J)<1.4 colour criteria can separate contaminants from true z>6 galaxies, although these are applicable to only 54% of the contaminants, as many have unconstrained (I-Y) colours. In the most optimistic scenario, these cuts reduce the contamination fraction to 1% whilst preserving 81% of the fiducial z>6 sample. For the faint mock sample, colour cuts are infeasible.

arXiv comment27 pages, 14 figures, 9 tables; version accepted for publication by A&A

References in corpus (64)

• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• The Global Schmidt Law in Star Forming Galaxies
• LSST: from Science Drivers to Reference Design and Anticipated Data Products
• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• The Spitzer Space Telescope Mission
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products and Mosaics
• The Cosmic Evolution Survey (COSMOS) -- Overview
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• EAZY: A Fast, Public Photometric Redshift Code
• Accurate photometric redshifts for the CFHT Legacy Survey calibrated using the VIMOS VLT Deep Survey
• COSMOS Photometric Redshifts with 30-bands for 2-deg2
• The propagation of uncertainties in stellar population synthesis modeling III: model calibration, comparison, and evaluation
• The COSMOS2015 Catalog: Exploring the 1<z<6 Universe with half a million galaxies
• Measuring and Modelling the Redshift Evolution of Clustering: the Hubble Deep Field North
• Spectral Energy Distributions of Hard X-ray selected AGNs in the XMDS Survey
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years
• Second Data Release of the Hyper Suprime-Cam Subaru Strategic Program
• The Abundance of Star-Forming Galaxies in the Redshift Range 8.5 to 12: New Results from the 2012 Hubble Ultra Deep Field Campaign
• The Chandra COSMOS Legacy survey: overview and point source catalog
• COSMOS2020: A panchromatic view of the Universe to $z\sim 10$ from two complementary catalogs
• 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
• An updated analytic model for the attenuation by the intergalactic medium
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• A Critical Assessment of Photometric Redshift Methods: A CANDELS Investigation
• Discovery of z~8 Galaxies in the HUDF from ultra-deep WFC3/IR Observations
• The VISTA Deep Extragalactic Observations (VIDEO) Survey
• The Evolution of the Galaxy Stellar Mass Function at z= 4-8: A Steepening Low-mass-end Slope with Increasing Redshift
• The Most Luminous z~9-10 Galaxy Candidates yet Found: The Luminosity Function, Cosmic Star-Formation Rate, and the First Mass Density Estimate at 500 Myr
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• The XMM-Newton Wide-Field Survey in the COSMOS field (XMM-COSMOS): demography and multiwavelength properties of obscured and unobscured luminous AGN
• New observations of z~7 galaxies: evidence for a patchy reionization
• A lack of evolution in the very bright-end of the galaxy luminosity function from z = 8-10
• Very Strong Emission-Line Galaxies in the WISP Survey and Implications for High-Redshift Galaxies
• The bright end of the galaxy luminosity function at z ~ 7: before the onset of mass quenching?
• Encoding the infrared excess (IRX) in the NUVrK color diagram for star-forming galaxies
• The galaxy luminosity function at z ~ 6 and evidence for rapid evolution in the bright end from z ~ 7 to 5
• The VLA-COSMOS 3~GHz Large Project: AGN and host-galaxy properties out to z$\lesssim$6
• 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
• CANDELS Multiwavelength Catalogs: Source Identification and Photometry in the CANDELS COSMOS Survey Field
• Properties of $z\sim 3-6$ Lyman Break Galaxies. II. Impact of nebular emission at high redshift
• The Brightest $z\gtrsim 8$ Galaxies over the COSMOS UltraVISTA Field
• Euclid preparation: X. The Euclid photometric-redshift challenge
• The Taiwan ECDFS Near-Infrared Survey: Ultra-deep J and Ks Imaging in the Extended Chandra Deep Field-South
• Spitzer bright, UltraVISTA faint sources in COSMOS: the contribution to the overall population of massive galaxies at z=3-7
• Expanded Search for z~10 Galaxies from HUDF09, ERS, and CANDELS Data: Evidence for Accelerated Evolution at z>8?
• The Reionization Lensing Cluster Survey (RELICS) and the Brightest High-z Galaxies
• Euclid preparation. XVIII. The NISP photometric system
• Further constraints on the evolution of Ks-selected galaxies in the GOODS/CDFS field
• Euclid preparation: XVIII. Cosmic Dawn Survey. Spitzer observations of the Euclid deep fields and calibration fields
• Spitzer Matching survey of the UltraVISTA ultra-deep Stripes (SMUVS): Full-mission IRAC Mosaics and Catalogs
• First observational support for overlapping reionized bubbles generated by a galaxy overdensity
• An exponential decline at the bright end of the z=6 galaxy luminosity function
• Infrared Selection of Obscured Active Galactic Nuclei in the COSMOS Field
• Mid-Infrared Selection of Brown Dwarfs and High-Redshift Quasars
• The Physical Properties of Luminous $z\gtrsim 8$ Galaxies and Implications for the Cosmic Star Formation Rate Density From $\sim$0.35 deg${}^2$ of (Pure-)Parallel HST Observations
• Characterization and modeling of contamination for Lyman break galaxy samples at high redshift
• The Spitzer Matching Survey of the UltraVISTA Ultra-deep Stripes (SMUVS): the Evolution of Dusty and Non-Dusty Galaxies with Stellar Mass at z=2-6
• Euclid: The selection of quiescent and star-forming galaxies using observed colours
• CLASH: Extreme Emission Line Galaxies and Their Implication on Selection of High-Redshift Galaxies

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• Euclid. I. Overview of the Euclid mission
• The bright end of the galaxy luminosity function at $z\simeq 7$ from the VISTA VIDEO survey
• A First Look into the Nature of JWST/MIRI 7.7 micron Sources from SMACS 0723
• Mapping reionization bubbles in the JWST era I: empirical edge detection with Lyman alpha emission from galaxies
• No Need for Extreme Stellar Masses at z~7: A Test-case Study of COS-87259
• Euclid: Identifying the reddest high-redshift galaxies in the Euclid Deep Fields with gradient-boosted trees
• Euclid: Discovery of bright $z\simeq 7$ Lyman-break galaxies in UltraVISTA and Euclid COSMOS