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arXiv · 2503.19440

KiDS-Legacy: Redshift distributions and their calibration

Angus H. Wright·Hendrik Hildebrandt·Jan Luca van den Busch·Maciej Bilicki·Catherine Heymans·Benjamin Joachimi·Constance Mahony·Robert Reischke·Benjamin Stölzner·Anna Wittje·Marika Asgari·Nora Elisa Chisari·Andrej Dvornik·Christos Georgiou·Benjamin Giblin·Henk Hoekstra·Priyanka Jalan·Anjitha John William·Shahab Joudaki·Konrad Kuijken·Giorgio Francesco Lesci·Shun-Sheng Li·Laila Linke·Arthur Loureiro·Matteo Maturi·Lauro Moscardin·Lucas Porth·Mario Radovich·Tilman Tröster·Maximilian von Wietersheim-Kramsta·Ziang Yan·Mijin Yoon·Yun-Hao Zhang
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Abstract

We present the redshift calibration methodology and bias estimates for the cosmic shear analysis of the fifth and final data release (DR5) of the Kilo-Degree Survey (KiDS). KiDS-DR5 includes a greatly expanded compilation of calibrating spectra, drawn from $27$ square degrees of dedicated optical and near-IR imaging taken over deep spectroscopic fields. The redshift distribution calibration leverages a range of new methods and updated simulations to produce the most precise $N(z)$ bias estimates used by KiDS to date. Improvements to our colour-based redshift distribution measurement method (SOM) mean that we are able to use many more sources per tomographic bin for our cosmological analyses, and better estimate the representation of our source sample given the available spec-$z$. We validate our colour-based redshift distribution estimates with spectroscopic cross-correlations (CC). We find that improvements to our cross-correlation redshift distribution measurement methods mean that redshift distribution biases estimated between the SOM and CC methods are fully consistent on simulations, and the data calibration is consistent to better than $2σ$ in all tomographic bins.

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Angus H. Wright, Hendrik Hildebrandt, Jan Luca van den Busch, Maciej Bilicki, Catherine Heymans, Benjamin Joachimi, Constance Mahony, Robert Reischke, Benjamin Stölzner, Anna Wittje, Marika Asgari, Nora Elisa Chisari, Andrej Dvornik, Christos Georgiou, Benjamin Giblin, Henk Hoekstra, Priyanka Jalan, Anjitha John William, Shahab Joudaki, Konrad Kuijken, Giorgio Francesco Lesci, Shun-Sheng Li, Laila Linke, Arthur Loureiro, Matteo Maturi, Lauro Moscardin, Lucas Porth, Mario Radovich, Tilman Tröster, Maximilian von Wietersheim-Kramsta, Ziang Yan, Mijin Yoon, Yun-Hao Zhang. 2025-10-21. KiDS-Legacy: Redshift distributions and their calibration. https://doi.org/10.1051/0004-6361%2F202554909

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