Euclid: Early Release Observations – NISP-only sources and the search for luminous 𝑧 = 6– 8 galaxies

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May 22, 2024
22 pages
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20222023202401
Abstract: (arXiv)
This paper presents a search for high redshift galaxies from the Euclid Early Release Observations program "Magnifying Lens." The 1.5 deg2^2 area covered by the twin Abell lensing cluster fields is comparable in size to the few other deep near-infrared surveys such as COSMOS, and so provides an opportunity to significantly increase known samples of rare UV-bright galaxies at zβ‰ˆ6βˆ’8z\approx6-8 (MUVβ‰²βˆ’22M_{\rm UV}\lesssim-22). Beyond their still uncertain role in reionisation, these UV-bright galaxies are ideal laboratories from which to study galaxy formation and constrain the bright-end of the UV luminosity function. Of the 501994 sources detected from a combined YEY_{\rm E}, JEJ_{\rm E}, and HEH_{\rm E} NISP detection image, 168 do not have any appreciable VIS/IEI_{\rm E} flux. These objects span a range in spectral colours, separated into two classes: 139 extremely red sources; and 29 Lyman-break galaxy candidates. Best-fit redshifts and spectral templates suggest the former is composed of both z≳5z\gtrsim5 dusty star-forming galaxies and zβ‰ˆ1βˆ’3z\approx1-3 quiescent systems. The latter is composed of more homogeneous Lyman break galaxies at zβ‰ˆ6βˆ’8z\approx6-8. In both cases, contamination by L- and T-type dwarfs cannot be ruled out with Euclid images alone. Additional contamination from instrumental persistence is investigated using a novel time series analysis. This work lays the foundation for future searches within the Euclid Deep Fields, where thousands more z≳6z\gtrsim6 Lyman break systems and extremely red sources will be identified.
Note:
  • 22 pages, 13 figures, paper submitted as part of the A&A special issue `Euclid on Sky', which contains Euclid key reference papers and first results from the Euclid Early Release Observations