Galaxy tagging : photometric redshift refinement and group richness enhancement
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We present a new scheme, galtag, for refining the photometric redshift measurements of faint galaxies by probabilistically tagging them to observed galaxy groups constructed from a brighter, magnitude-limited spectroscopy survey. First, this method is tested on the DESI light-cone data constructed on the galform galaxy formation model to tests its validity. We then apply it to the photometric observations of galaxies in the Kilo-Degree Imaging Survey (KiDS) over a 1 deg2 region centred at 15h. This region contains Galaxy and Mass Assembly (GAMA) deep spectroscopic observations (i band < 22) and an accompanying group catalogue to r band < 19.8. We demonstrate that even with some trade-off in sample size, an order of magnitude improvement on the accuracy of photometric redshifts is achievable when using galtag. This approach provides both refined photometric redshift measurements and group richness enhancement. In combination these products will hugely improve the scientific potential of both photometric and spectroscopic data sets. The galtag software will be made publicly available at https://github.com/pkaf/galtag.git.
Kafle , P R , Robotham , A S G , Driver , S P , Deeley , S , Norberg , P , Drinkwater , M J & Davies , L J 2018 , ' Galaxy tagging : photometric redshift refinement and group richness enhancement ' , Monthly Notices of the Royal Astronomical Society , vol. 479 , no. 3 , pp. 3746–3758 . https://doi.org/10.1093/mnras/sty1536
Monthly Notices of the Royal Astronomical Society
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This work has been made available online in accordance with the publisher's policies. This is the final published version of the work, which was originally published at https://doi.org/10.1093/mnras/sty1536
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