Bright galaxy sample in the Kilo-Degree Survey Data Release 4

Astronomy and Astrophysics, vol. 653, pp. A82

Abstract

We present a bright galaxy sample with accurate and precise photometric redshifts (photo- z s), selected using ugriZYJHK s photometry from the Kilo-Degree Survey (KiDS) Data Release 4. The highly pure and complete dataset is flux-limited at r < 20 mag, covers ∼1000 deg 2 , and contains about 1 million galaxies after artifact masking. We exploit the overlap with Galaxy And Mass Assembly spectroscopy as calibration to determine photo- z s with the supervised machine learning neural network algorithm implemented in the ANNz2 software. The photo- z s have a mean error of |⟨ δz ⟩|∼5 × 10 −4 and low scatter (scaled mean absolute deviation of ∼0.018(1 + z )); they are both practically independent of the r -band magnitude and photo- z at 0.05 < z phot < 0.5. Combined with the 9-band photometry, these allow us to estimate robust absolute magnitudes and stellar masses for the full sample. As a demonstration of the usefulness of these data, we split the dataset into red and blue galaxies, used them as lenses, and measured the weak gravitational lensing signal around them for five stellar mass bins. We fit a halo model to these high-precision measurements to constrain the stellar-mass–halo-mass relations for blue and red galaxies. We find that for high stellar mass ( M ⋆ > 5 × 10 11 M ⊙ ), the red galaxies occupy dark matter halos that are much more massive than those occupied by blue galaxies with the same stellar mass.

Authors 19

1. Maciej Bilicki

   Center for Theoretical Physics · Polish Academy of Sciences

   Affiliation as printed

   Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland

2. Andrej Dvornik Aachen Leiden Observatory

   Leiden University · Leiden Observatory · Ruhr University Bochum

   Affiliation as printed

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

   Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing, 44780 Bochum, Germany

3. Henk Hoekstra Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

4. Angus H. Wright

   Ruhr University Bochum

   Affiliation as printed

   Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing, 44780 Bochum, Germany

5. Nora Elisa Chisari

   Utrecht University

   Affiliation as printed

   Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands

6. Mohammadjavad Vakili Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

7. Marika Asgari

   University of Edinburgh

   Affiliation as printed

   Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK

8. Benjamin Giblin

   University of Edinburgh

   Affiliation as printed

   Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK

9. Catherine Heymans

   Ruhr University Bochum · University of Edinburgh

   Affiliation as printed

   Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK

   Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing, 44780 Bochum, Germany

10. Hendrik Hildebrandt

    Ruhr University Bochum

    Affiliation as printed

    Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing, 44780 Bochum, Germany

11. Benne Willem Holwerda

    University of Louisville

    Affiliation as printed

    Department of Physics and Astronomy, University of Louisville, 102 Natural Science Building, Louisville, KY 40292, USA

12. Andrew Hopkins

    Australian Astronomical Optics

    Affiliation as printed

    Australian Astronomical Optics, Macquarie University, 105 Delhi Rd, North Ryde, NSW 2113, Australia

13. Harry Johnston

    Utrecht University

    Affiliation as printed

    Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands

14. Arun Kannawadi

    Princeton University

    Affiliation as printed

    Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA

15. Konrad H. Kuijken Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

16. Szymon J. Nakoneczny

    National Centre for Nuclear Research

    Affiliation as printed

    National Centre for Nuclear Research, Astrophysics Division, ul. Pasteura 7, 02-093 Warsaw, Poland

17. Huanyuan Shan

    Shanghai Astronomical Observatory · University of Chinese Academy of Sciences

    Affiliation as printed

    Shanghai Astronomical Observatory (SHAO), Nandan Road 80, Shanghai 200030, PR China

    University of Chinese Academy of Sciences, Beijing 100049, PR China

18. Alessandro Sonnenfeld Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

19. Edwin A. Valentijn

    University of Groningen

    Affiliation as printed

    Kapteyn Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands