Spatially resolved PAH_3.3 emission and stellar ages in ram pressure stripped clumps at z ∼ 0.3

¹ INAF, Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 35122 Padova, Italy
² Dipartimento di Fisica e Astronomia ‘G. Galilei’, Università di Padova Vicolo dell’Osservatorio 3 35122 Padova, Italy
³ Instituto de Radioastronomia y Astrofisica, UNAM, Campus Morelia A.P. 3-72 C.P. 58089 Morelia, Mexico
⁴ IPAC, California Institute of Technology 1200 E. California Blvd. Pasadena CA 91125, USA
⁵ University of California, Los Angeles, Department of Physics and Astronomy 430 Portola Plaza Los Angeles CA 90095, USA

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

Received: 7 November 2025
Accepted: 22 December 2025

Abstract

Ram pressure stripping (RPS) plays a crucial role in shaping galaxy evolution in dense environments, yet its impact on the molecular and dusty phases of the interstellar medium remains poorly understood. We present JWST/NIRCam 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission maps for the nine most striking RPS galaxies in the Abell 2744 cluster at redshift z_cl = 0.306, tracing the effects of environmental processes on small dust grains. Exploiting multi-band JWST/NIRCam and HST photometry, we performed a spatially resolved ultraviolet (UV) to mid-infrared (MIR) spectral energy distribution (SED) fitting to characterise stellar populations in both galactic disks and clumps detected in the stripped tails. We detected PAH_3.3 emission in eight of the nine galaxies at 5σ, with morphologies revealing disk truncation and elongation along the RPS direction. In three galaxies, PAH_3.3 emission is also found in star-forming clumps embedded in the stripped tails up to a distance of 40 kpc. Star formation rates inferred from PAH_3.3 emission are in agreement with those derived from SED fitting averaged over the past 100 Myr within an intrinsic scatter of 0.4 dex, but the relation appears to be age-dependent. The spatial correlation between the PAH strength, stellar age, and star formation rate (SFR) is consistent across disks and tails and demonstrates that PAH-carrying molecules can survive and become stripped by ram pressure. Finally, age gradients revealed by the SED fitting provide observational evidence of the fireball model in star-forming, stripped clumps of galaxies at z ∼ 0.3. This work represents the first detailed study of PAH emission in cluster galaxies, offering new insights into the fate of dust and star formation in extreme environments.