The S-PLUS Fornax Project (S+FP): Mapping Hα+[N II] emission in 77 Fornax galaxy members reaching ∼4 Rvir

¹ Instituto de Astrofísica de La Plata, CONICET-UNLP, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
² Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
³ Universidade de São Paulo, IAG, Rua do Matão 1226, São Paulo, SP, Brazil
⁴ Universidad de Investigación y Desarrollo, Departamento de Ciencias Básicas y Humanas, Grupo FIELDS, Calle 9 No. 23-55, Bucaramanga, Colombia
⁵ Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1600, 2390123, Valparaíso, Chile
⁶ Departamento de Astronomía, Universidad de La Serena, Av. J. Cisternas 1200 N, 1720236 La Serena, Chile
⁷ Observatório Nacional, Rua General José Cristino, 77, São Cristóvão, 20921-400 Rio de Janeiro, RJ, Brazil
⁸ Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK
⁹ Instituto de Física, Universidade Federal do Rio de Janeiro, 21941-972, Rio de Janeiro, Brazil
¹⁰ Observatório do Valongo, Ladeira Pedro Antonio, 43, 20080-090, Rio de Janeiro, Brazil
¹¹ Departamento de Física – CFM – Universidade Federal de Santa Catarina, PO BOx 476, 88040-900, Florianópolis, SC, Brazil
¹² Cambridge Survey Astronomical Unit (CASU), Insitute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, GB, UK
¹³ Instituto Argentino de Radioastronomía, CONICET-CICPBA-UNLP, CC5 (1894) Villa Elisa, Provincia de Buenos Aires, Argentina
¹⁴ Institute of Astrophysics, Facultad de Ciencias Exactas, Universidad Andrés Bello, Sede Concepción, Talcahuano, Chile
¹⁵ Instituto Multidisciplinario de Investigación y Postgrado, Universidad de La Serena, Raúl Bitrán 1305, 1700000 La Serena, Chile
¹⁶ Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
¹⁷ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal
¹⁸ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, 4169-007, Porto, Portugal
¹⁹ Departamento de Tecnologías Industriales, Facultad de Ingeniería, Universidad de Talca, Los Niches km 1, Curicó, Chile
²⁰ Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
²¹ Instituto Nacional de Pesquisas Espaciais, Av. dos Astronautas 1758, Jardim da Granja, 12227-010 São José dos Campos, SP, Brazil
²² Universidade Presbiteriana Mackenzie, Rua da Consolação, 930 – Consolação, São Paulo, Brazil
²³ GMTO Corporation 465 N. Halstead Street, Suite 250 Pasadena, CA 91107, USA
²⁴ Rubin Observatory Project Office, 950 N. Cherry Ave., Tucson, AZ 85719, USA

^⋆ Corresponding author: amandalopes1920@gmail.com

Received: 17 February 2025
Accepted: 19 May 2025

Abstract

Context. The Fornax cluster, the second-largest galaxy cluster within 20 Mpc, presents an ideal environment for studying the impact of environmental effects on galaxy evolution. Utilizing data from the Southern Photometric Local Universe Survey (S-PLUS), this study explores the Hα+[N II] emission maps in Fornax and its outskirts.

Aims. By mapping emission features across an area of approximately 208 square degrees around NGC 1399, this work aims to identify and characterize emission-line galaxies (ELGs) and analyze their spatial distribution, morphology, and their projected phase space (PPS) diagram.

Methods. We developed a dedicated semiautomated pipeline, pixel-to-pixel emission line estimate (PELE), to generate emission line maps by processing S-PLUS images using the three-filter method. A morphological analysis was conducted using the ASTROMORPHLIB package to determine whether Hα+[N II] emitters exhibit perturbed features.

Results. The study successfully detected 77 Hα+[N II] emitters with r_AB<18 mag, extending to four times the virial radius of the Fornax cluster. PELE demonstrated its ability to recover flux down to ∼2×10⁻¹⁷ erg s⁻¹ cm⁻² when compared to Hα maps from MUSE/VLT. Among the emitters, 25% are early-type galaxies (ETGs) and 75% are late-type galaxies (LTGs). Signs of morphological perturbation or merger activity are observed in 44% of the LTGs and in three ETGs located beyond the clusters virial radius. A significant fraction (91%) of the emitters are identified as recent infallers, which are primarily located in the northwestern region of the cluster, while others are associated with the infalling group Fornax A in the southwest. Disturbed, low-mass galaxies at larger cluster-centric distances provide evidence that galaxies begin transforming before entering the main cluster.

Conclusions. This study demonstrates S-PLUS's effectiveness in detecting ELGs, whose distribution reflects the Fornax cluster's assembly history; LTGs are linked to recent infall from the field, possibly along a Fornax-Eridanus filament, and ETGs may have evolved prior to entry.