Galaxy tagging: Photometric redshift refinement and group richness enhancement

P. R. Kafle, A. S.G. Robotham, S. P. Driver, S. Deeley, P. Norberg, M. J. Drinkwater, L. J. Davies

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Abstract

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, thismethod is tested on the DESI lightcone 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.

Original languageEnglish
Pages (from-to)3746-3758
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Volume479
Issue number3
DOIs
Publication statusPublished - 21 Sep 2018

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tagging
marking
galaxies
augmentation
trade-off
galactic clusters
spectroscopy
refining
galactic evolution
software
catalogs
assembly
computer programs
products
test
product

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title = "Galaxy tagging: Photometric redshift refinement and group richness enhancement",
abstract = "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, thismethod is tested on the DESI lightcone 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.",
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Galaxy tagging : Photometric redshift refinement and group richness enhancement. / Kafle, P. R.; Robotham, A. S.G.; Driver, S. P.; Deeley, S.; Norberg, P.; Drinkwater, M. J.; Davies, L. J.

In: Monthly Notices of the Royal Astronomical Society, Vol. 479, No. 3, 21.09.2018, p. 3746-3758.

Research output: Contribution to journalArticle

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AU - Driver, S. P.

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AU - Norberg, P.

AU - Drinkwater, M. J.

AU - Davies, L. J.

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