Unveiling multiple physical processes on a cluster galaxy at z = 0.3 using JWST

¹ INAF – Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy
² School of Physics, University of Melbourne, Parkville, Vic 3010, Australia
³ Australian Research Council Centre of Excellence for All-Sky Astrophysics in 3-Dimensions, Australia
⁴ School of Astronomy and Space Science, University of Chinese Academy of Sciences (UCAS), Beijing 100049, China
⁵ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
⁶ Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, China
⁷ Center for Astrophysical Sciences, William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA

^⋆ Corresponding author: peter.watson@inaf.it

Received: 23 September 2024
Accepted: 4 June 2025

Abstract

We present a study of a previously identified candidate jellyfish galaxy in the Abell 2744 cluster, F0083, which showed faint signs of a tidal interaction in archival imaging. We used publicly available PSF-matched deep photometric data from the Hubble and James Webb Space Telescopes to infer the spatially resolved star formation history of this galaxy. F0083 shows clear signs of ram-pressure stripping (RPS), with a recently enhanced star formation rate (SFR) orientated towards the south-west quadrant of the stellar disc. The stellar mass surface density is heavily asymmetric, with a variation of nearly 1 dex between the western spiral arm and the postulated tidal feature. This feature appears to contain a high proportion of older stars, ruling out RPS as the cause of this ‘unwinding’. We identified two potential interaction candidates, 28171 and 26055, with masses log₁₀(M_*/M_⊙) = 8.56 ± 0.06 and log₁₀(M_*/M_⊙) = 9.24 ± 0.09, respectively, and projected separations of 31 kpc and 46 kpc. The star formation history (SFH) of the tidal feature in F0083 indicates a steep change in SFR at lookback times t_L≲1 Gyr, consistent with a burst in the SFH of 26055. The most probable formation scenario of F0083 thus indicates a significant tidal interaction, followed by RPS as the combined system approaches pericentre passage. Our results demonstrate that by using photometric data we are able to distinguish between these consecutive processes, and represent the first observational analysis of the contributions of each process at this redshift.