Spatially-resolved PAH_3.3 emission and stellar ages in ram pressure stripped clumps at z~0.3 (2511.05113v1)

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 micrometres 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 perform spatially-resolved UV to mid-infrared spectral energy distribution (SED) fitting, characterising stellar populations in both galactic disks and clumps detected in the stripped tails. We detect PAH_3.3 mission in eight of the nine galaxies at 5 sigma, 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 agree 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 PAH strength, stellar age, and SFR - consistent across disks and tails - demonstrates that PAH-carrying molecules can survive and be stripped by ram pressure. Finally, age gradients revealed by the SED fitting provide the first observational evidence outside the Local Universe for the fireball model of star formation in stripped clumps. 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.