A GMOS/IFU Study of Jellyfish Galaxies in Massive Clusters

TL;DR

This study uses GMOS/IFU observations to analyze the ionized gas properties of five jellyfish galaxies in massive clusters, revealing high star formation rates and the effects of ram-pressure stripping in dense environments.

Contribution

It provides detailed kinematic and star formation analyses of jellyfish galaxies at intermediate redshifts, highlighting the impact of RPS on star formation activity.

Findings

High star formation rates in these jellyfish galaxies.

Ionized gas kinematics consistent with disk rotation and RPS effects.

Enhanced star formation linked to galaxy mass and cluster velocity dispersion.

Abstract

Jellyfish galaxies are an intriguing snapshot of galaxies undergoing ram-pressure stripping (RPS) in dense environments, showing spectacular star-forming knots in their disks and tails. We study the ionized gas properties of five jellyfish galaxies in massive clusters with Gemini GMOS/IFU observations: MACSJ0916-JFG1 ($z=0.330$), MACSJ1752-JFG2 ($z=0.353$), A2744-F0083 ($z=0.303$), MACSJ1258-JFG1 ($z=0.342$), and MACSJ1720-JFG1 ($z=0.383$). BPT diagrams show that various mechanisms (star formation, AGN, or mixed effects) are ionizing gas in these galaxies. Radial velocity distributions of ionized gas seem to follow disk rotation of galaxies, with the appearance of a few high-velocity components in the tails as a sign of RPS. Mean gas velocity dispersion is lower than 50 \kms~in most star-forming regions except near AGNs or shock-heated regions, indicating that the ionized gas %in these star-forming regions is dynamically cold. Integrated star formation rates (SFRs) of these galaxies range from $7~{\rm M_{\odot}~{\rm yr^{-1}}}$ to $35~{\rm M_{\odot}~{\rm yr^{-1}}}$ and the tail SFRs are from $0.6~{\rm M_{\odot}~{\rm yr^{-1}}}$ to $16~{\rm M_{\odot}~{\rm yr^{-1}}}$, which are much higher than those of other jellyfish galaxies in the local universe. These high SFR values imply that RPS triggers intense star formation activity in these extreme jellyfish galaxies. The phase-space diagrams demonstrate that the jellyfish galaxies with higher stellar masses and higher host cluster velocity dispersion are likely to have more enhanced star formation activity. The jellyfish galaxies in this study have similar gas kinematics and dynamical states to those in the local universe, but they show a much higher SFR.