TOPz: Photometric redshifts for J-PAS

¹ Tartu Observatory, University of Tartu, Observatooriumi 1, 61602 Tõravere, Estonia
e-mail: jaan.laur@ut.ee
² Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia
³ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan, 1, 44001 Teruel, Spain
⁴ Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 Donostia-San Sebastián, Spain
⁵ Instituto de Astrofísica de Andalucía (CSIC), PO Box 3004, 18080 Granada, Spain
⁶ Departamento de Astronomia, Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Porto Alegre, RS, Brazil
⁷ Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, CEP 22290-180, Rio de Janeiro, RJ, Brazil
⁸ Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Rodovia Mário Covas, lote J2, quadra J, CEP 23810-000, Itaguaí, RJ, Brazil
⁹ Instituto de Física, Universidade de Sãoo Paulo, Rua do Matãoo 1371, 05508-090 Sãoo Paulo, Brazil
¹⁰ Observatório Nacional, Ministério da Ciencia, Tecnologia, Inovação e Comunicações, Rua General José Cristino, 77, São Cristóvão, 20921-400 Rio de Janeiro, Brazil
¹¹ Instituto de Física, Universidade Federal da Bahia, 40210-340, Salvador, BA, Brazil
¹² Centro de Estudios de de Física del Cosmos de Aragón (CEFCA), Unidad Asociada al CSIC, Plaza San Juan, 1, 44001 Teruel, Spain
¹³ Instruments4, 4121 Pembury Place, La Canada Flintridge, CA 91011, USA

Received: 27 April 2022
Accepted: 25 August 2022

Abstract

Context. The importance of photometric galaxy redshift estimation is rapidly increasing with the development of specialised powerful observational facilities.

Aims. We develop a new photometric redshift estimation workflow TOPz to provide reliable and efficient redshift estimations for the upcoming large-scale survey J-PAS which will observe 8500 deg² of the northern sky through 54 narrow-band filters.

Methods. TOPz relies on template-based photo-z estimation with some added J-PAS specific features and possibilities. We present TOPz performance on data from the miniJPAS survey, a precursor to the J-PAS survey with an identical filter system. First, we generated spectral templates based on the miniJPAS sources using the synthetic galaxy spectrum generation software CIGALE. Then we applied corrections to the input photometry by minimising systematic offsets from the template flux in each filter. To assess the accuracy of the redshift estimation, we used spectroscopic redshifts from the DEEP2, DEEP3, and SDSS surveys, available for 1989 miniJPAS galaxies with r < 22 mag_AB. We also tested how the choice and number of input templates, photo-z priors, and photometric corrections affect the TOPz redshift accuracy.

Results. The general performance of the combination of miniJPAS data and the TOPz workflow fulfills the expectations for J-PAS redshift accuracy. Similarly to previous estimates, we find that 38.6% of galaxies with r < 22 mag reach the J-PAS redshift accuracy goal of dz/(1 + z) < 0.003. Limiting the number of spectra in the template set improves the redshift accuracy up to 5%, especially for fainter, noise-dominated sources. Further improvements will be possible once the actual J-PAS data become available.