A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies

Details A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies

2008-12-19

arxiv.org/abs/0812.3831v1

Astronomy and Astrophysics

Astrophysics

14 pages, 8 figures, submitted to MNRAS

Scientific paper

We present an updated version of MegaZ-LRG (Collister et al.,(2007)) with photometric redshifts derived with the neural network method, ANNz as well as five other publicly available photo-z codes (HyperZ, SDSS, Le PHARE, BPZ and ZEBRA) for ~1.5 million Luminous Red Galaxies (LRGs) in SDSS DR6. This allows us to identify how reliable codes are relative to each other if used as described in their public release. We compare and contrast the relative merits of each code using ~13000 spectroscopic redshifts from the 2SLAQ sample. We find that the performance of each code depends on the figure of merit used to assess it. As expected, the availability of a complete training set means that the training method performs best in the intermediate redshift bins where there are plenty of training objects. Codes such as Le PHARE, which use new observed templates perform best in the lower redshift bins. All codes produce reasonable photometric redshifts, the 1-sigma scatters ranging from 0.057 to 0.097 if averaged over the entire redshift range. We also perform tests to check whether a training set from a small region of the sky such as 2SLAQ produces biases if used to train over a larger area of the sky. We conclude that this is not likely to be a problem for future wide-field surveys. The complete photometric redshift catalogue including redshift estimates and errors on these from all six methods can be found at www.star.ucl.ac.uk/~mbanerji/MegaZLRGDR6/megaz.html

Affiliated with

Also associated with

No associations

Rating

A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-727185