The miniJPAS survey: Photometric redshift catalogue
A. Hernán-Caballero, J. Varela, C. López-Sanjuan, D. Muniesa, T. Civera, J. Chaves-Montero, L. A. Díaz-García, J. Laur, C. Hernández-Monteagudo, R. Abramo, R. Angulo, D. Cristóbal-Hornillos, R. M. González Delgado, N. Greisel, A. Orsi, C. Queiroz, D. Sobral, A. Tamm, E. Tempel, H. Vázquez-Ramió, J. Alcaniz, N. Benítez, S. Bonoli, S. Carneiro, J. Cenarro, R. Dupke, A. Ederoclite, A. Marín-Franch, C. Mendes de Oliveira, M. Moles, L. Sodré, K. Taylor, E. S. Cypriano, G. Martínez-Solaeche
Abstract
MiniJPAS is a ∼1 deg 2 imaging survey of the AEGIS field in 60 bands, performed to demonstrate the scientific potential of the upcoming Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS). Full coverage of the 3800–9100 Å range with 54 narrow-band filters, in combination with 6 optical broad-band filters, allows for extremely accurate photometric redshifts (photo- z ), which, applied over areas of thousands of square degrees, will enable new applications of the photo- z technique, such as measurement of baryonic acoustic oscillations. In this paper we describe the method we used to obtain the photo- z that is included in the publicly available miniJPAS catalogue, and characterise the photo- z performance. We built photo-spectra with 100 Å resolution based on forced-aperture photometry corrected for point spread function. Systematic offsets in the photometry were corrected by applying magnitude shifts obtained through iterative fitting with stellar population synthesis models. We computed photo- z with a customised version of L E P HARE , using a set of templates that is optimised for the J-PAS filter-set. We analysed the accuracy of miniJPAS photo- z and their dependence on multiple quantities using a subsample of 5266 galaxies with spectroscopic redshifts from SDSS and DEEP, which we find to be representative of the whole r < 23 miniJPAS sample. Formal 1 σ uncertainties for the photo- z that are calculated with the Δ χ 2 method underestimate the actual redshift errors. The o d d s parameter has a stronger correlation with |Δ z | and accurately reproduces the probability of a redshift outlier (|Δ z | > 0.03), regardless of the magnitude, redshift, or spectral type of the sources. We show that the two main summary statistics characterising the photo- z accuracy for a population of galaxies ( σ NMAD and η ) can be predicted by the distribution of o d d s in this population, and we use this to estimate the statistics for the whole miniJPAS sample. At r < 23, there are ∼17 500 galaxies per deg 2 with valid photo- z estimates, ∼4200 of which are expected to have |Δ z | < 0.003. The typical error is σ NMAD = 0.013 with an outlier rate η = 0.39. The target photo- z accuracy σ NMAD = 0.003 is achieved for o d d s > 0.82 with η = 0.05, at the cost of decreasing the density of selected galaxies to n ∼ 5200 deg −2 (∼2600 of which have |Δ z | < 0.003).