Oral Presentation

Deep Optical Imaging by Subaru Hyper Suprime-Cam of the AKARI North Ecliptic Pole Field: Photometric Redshift and Source properties

Author(s): Chien-Chang Ho(NTHU), Tomotsugu Goto(NTHU), Nagisa Oi(Tokyo University of Science, Tokyo, Japan), Seong Jin Kim(NTHU), Tetsuya Hashimoto(NTHU), Ting-Wen Wang(NTHU)

Presenter: Chien-Chang Ho (National Tsing Hua University)

We present and release photometric redshifts for 91861 objects
North Ecliptic Pole Wide (NEPW) Field Survey which cover a total effective area of 5.4 deg^2
We use 2026 spectroscopic redshifts with 0 ≤ z ≤ 5 from the North Ecliptic Pole Deep (NEPD) Field Survey as a calibration to derive these photometric redshifts. Using the “Le Phare” photometric redshift code, we developed a robust calibration
method based on an iterative zero-point refinement combined with a template based SED fitting procedure. We use our unique spectroscopic sample to present a detailed assessment of the robustness of the photometric redshift sample.
Results. For z < 1.5, we reach a redshift accuracy of σΔz/(1+z) = 0.0493 with η = 9.27% of catastrophic errors.
We also use Random forest, a Machine Learning approach to estimate photo-z. We find that the result is less reliable than template based approach in this case.
Finally, we investigate some of the source properties in our sample. We discuss about the photo-z of AGNs, stellarity of the sources, and the reliability of photo-z for faint sources. Moreover, we discuss the feasibility of machine learning in photo-z.