Euclid preparation: XX. The Complete Calibration of the Color-Redshift Relation survey: LBT observations and data release

Abstract

The Complete Calibration of the Color-Redshift Relation survey (C3R2) is a spectroscopic programme designed to empirically calibrate the galaxy color-redshift relation to the Euclid depth (I_E=24.5), a key ingredient for the success of Stage IV dark energy projects based on weak lensing cosmology. A spectroscopic calibration sample as representative as possible of the galaxies in the Euclid weak lensing sample is being collected, selecting galaxies from a self-organizing map (SOM) representation of the galaxy color space. Here, we present the results of a near-infrared H- and K-bands spectroscopic campaign carried out using the LUCI instruments at the LBT. For a total of 251 galaxies, we present new highly-reliable redshifts in the 1.3<= z <=1.7 and 2<= z<=2.7 ranges. The newly-determined redshifts populate 49 SOM cells which previously contained no spectroscopic measurements and almost double the occupation numbers of an additional 153 SOM cells. A final optical ground-based observational effort is needed to calibrate the missing cells in particular in the redshift range 1.7<= z<=2.7 that lack spectroscopic calibration. In the end, Euclid itself will deliver telluric-free NIR spectra that can complete the calibration.

arXiv commentA&A language edited version

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Cited by in corpus (5)

• Euclid. I. Overview of the Euclid mission
• DESI Complete Calibration of the Color-Redshift Relation (DC3R2): Results from early DESI data
• Euclid preparation. XXXI. The effect of the variations in photometric passbands on photometric-redshift accuracy
• Enhancing Photometric Redshift Catalogs Through Color-Space Analysis: Application to KiDS-Bright Galaxies
• GalSBI-SPS: a stellar population synthesis-based galaxy population model for cosmology and galaxy evolution applications