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.

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, 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 datasets. The galtag software will be made publicly available at https://github.com/pkaf/galtag.git.

Citation

Kafle, P., Robotham, A., Driver, S., Deeley, S., Norberg, P., Drinkwater, M., & Davies, L. (2018). Galaxy Tagging: photometric redshift refinement and group richness enhancement. Monthly Notices of the Royal Astronomical Society, 479(3), 3746-3758. https://doi.org/10.1093/mnras/sty1536

• Journal Article Type: Article
• Acceptance Date: Jun 7, 2018
• Online Publication Date: Jun 18, 2018
• Publication Date: Sep 21, 2018
• Deposit Date: Jul 11, 2018
• Publicly Available Date: Jul 12, 2018
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 479
• Issue: 3
• Pages: 3746-3758
• DOI: https://doi.org/10.1093/mnras/sty1536
• Public URL: https://durham-repository.worktribe.com/output/1326355