Spatially resolved PAH$_{3.3}$ emission and stellar ages in ram pressure stripped clumps at $z\sim0.3$

TL;DR

This study uses JWST observations to map PAH emission and analyze stellar ages in ram pressure stripped galaxies at z~0.3, revealing dust survival, star formation, and age gradients in stripped tails.

Contribution

First detailed analysis of PAH emission in cluster galaxies at z~0.3, linking dust, star formation, and stellar ages in ram pressure stripped environments.

Findings

PAH$_{3.3}$ emission detected in 8 of 9 galaxies, showing disk truncation and elongation.

Star formation rates from PAH emission agree with SED-based rates within 0.4 dex.

Age gradients support the fireball model in star-forming stripped clumps.

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 $3.3\mathrm{\mu m}$ 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 $5\sigma$, 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 $40\mathrm{kpc}$. Star formation rates inferred from PAH$_{3.3}$ emission are in agreement with those derived from SED fitting averaged over the past $100\mathrm{Myr}$ within an intrinsic scatter of $0.4\mathrm{dex}$, 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 $z \sim 0.3$. 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.