J-PAS: Unprecedented precision in stellar populations of diffuse tidal features

¹ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan 1, 44001, Teruel, Spain
² Unidad Asociada CEFCA-IAA, CEFCA, Unidad Asociada al CSIC por el IAA, Plaza San Juan 1, 44001, Teruel, Spain
³ Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38205, La Laguna, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, 38205, La Laguna, Spain
⁵ Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas (CSIC), Apdo 3004, E-18080, Granada, Spain
⁶ Instituto de Física de Cantabria (IFCA), CSIC-Univ. de Cantabria, Avda. los Castros, s/n, E-39005, Santander, Spain
⁷ Observatório Nacional, Ministério da Ciencia, Tecnologia, Inovação e Comunicações, Rua General José Cristino, 77, São Cristóvão, 20921-400, Rio de Janeiro, Brazil
⁸ Departamento de Astronomia, Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Porto Alegre, R.S, Brazil
⁹ Donostia International Physics Center (DIPC), Manuel Lardizabal Ibilbidea, 4, San Sebastián, Spain
¹⁰ Departamento de Astronomia, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, Brazil
¹¹ Instruments4, 4121 Pembury Place, La Canada Flintridge, CA, 91011, USA
¹² ARAID Foundation, Avda. de Ranillas, 1-D, E-50018, Zaragoza, Spain
¹³ Laboratoire d’Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), 1290, Sauverny, Switzerland
¹⁴ GEPI, Observatoire de Paris, CNRS UMR 8111, Université Paris Diderot, 92125, Meudon Cedex, France
¹⁵ Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, SE-221 00, Lund, Sweden
¹⁶ Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Plaza Ciencias, 1, 28040, Madrid, Spain
¹⁷ Leiden Observatory, Leiden University, J.H. Oort Building, Niels Bohrweg 2, 2333 CA, Leiden, Netherlands
¹⁸ National Astronomical Observatory of China, Chinese Academy of Sciences, Beijing, China

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 19 November 2025
Accepted: 10 March 2026

Abstract

Galaxies frequently interact with nearby systems, which can significantly alter their morphology and star formation activity. However, spectroscopic studies of their faint and diffuse remnants require very long exposure times and often exceed the limited field of view of integral field units (IFUs). On the other hand, broadband imaging can have a much wider field of view, but it lacks the spectral resolution to identify key spectral features, restricting accurate constraints on stellar population properties. With its 54 narrowband filters in the optical and wide coverage (8000 square degrees, planned), J-PAS fills this gap. In this case study, we examined PGC 3087775, a massive galaxy at z = 0.046179 (∼201 Mpc) in the later stages of a major merger in the J-PAS Early Data Release. Photometry was performed on visually identified polygons (over the tidal features) using Gnuastro and validated with MaNGA IFU data (for the central part). Spectral energy distribution (SED) fitting was then carried out with CIGALE to derive stellar population properties using both J-PAS and SDSS photometry to assess the added value with J-PAS. SDSS indicates a metal-rich population with an extended star formation history (SFH) and elevated star formation rates. J-PAS instead points to a less metal-rich population with moderate extinction and a more rapid SFH, consistent with a quenched stellar population. The average D_n(4000) index of the tidal features is 1.24, suggesting that it was a non-dry merger and a fourfold improvement in the precision of stellar mass and D_n(4000) was found with J-PAS. We also assessed two heuristic methods for estimating the mass-to-light ratio from SDSS filters and found that they overestimate the stellar mass in this galaxy by 0.5 dex and 0.4 dex relative to SED fitting results from J-PAS and SDSS, respectively. Future work will extend this analysis to a larger sample of merging galaxies and evolution of the stellar populations of such structures across the nearby Universe with unprecedented detail. This project and its results are fully reproducible, through Maneage (commit f2cb27a).