http://arxiv.org/abs/1910.08588
Cosmology and galaxy evolution studies with LSST, Euclid, and WFIRST, will require accurate redshifts for the detected galaxies. In this study, we present improved photometric redshift estimates for galaxies using a template library that populates three-color space and is constrained by HST/CANDELS photometry. For the training sample, we use a sample of galaxies which have median photometric redshifts derived by combining the results of different redshift-fitting codes. It allows us to train on a large, unbiased galaxy sample having deep, unconfused photometry at optical-to-mid infrared wavelengths. Galaxies in the training sample are assigned to cubes in three-dimensional color space, V-H, I-J, and z-H. We then derive the best-fit spectral energy distributions (SEDs) of the training sample at the fixed CANDELS median photometric redshifts to construct the new template library for each individual color cube (i.e. color-cube-based template library). We derive photometric redshifts (photo-z) of our target galaxies in the GOODS-S and -N fields using our new color-cube-based template library. We find that our method yields $\sigma_{NMAD}$ of 0.026 and an outlier fraction of 6% using only photometry in the LSST and Euclid/WFIRST bands. This is an improvement of 10% on $\sigma_{NMAD}$ and a reduction in outlier fraction of 13% compared to other techniques. In particular, we improve the photo-z precision by about 30% at 2 < z < 3. We also assess photo-z improvements by including K or mid-infrared bands to the ugrizY JH photometry. Our color-cube-based template library is a powerful tool to constrain photometric redshifts for future large surveys.
B. Lee and R. Chary
Tue, 22 Oct 19
61/91
Comments: 13 pages, 7 figures, 4 tables; ApJ submitted
You must be logged in to post a comment.