Jellyfish galaxies with the IllustrisTNG simulations - when, where, and for how long does ram pressure stripping of cold gas occur?

Eric Rohr*, Annalisa Pillepich, Dylan Nelson, Elad Zinger, Gandhali D. Joshi, Mohammadreza Ayromlou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Jellyfish galaxies are prototypical examples of satellite galaxies undergoing strong ram pressure stripping (RPS). We analyse the evolution of 512 unique, first-infalling jellyfish galaxies from the TNG50 cosmological simulation. These have been visually inspected to be undergoing RPS sometime in the past 5 Byr (since z = 0.5), have satellite stellar masses, and live in hosts with at z = 0. We quantify the cold gas (T ≤ 104.5 K) removal using the tracer particles, confirming that for these jellyfish, RPS is the dominant driver of cold gas loss after infall. Half of these jellyfish are completely gas-less by z = 0, and these galaxies have earlier infall times and smaller satellite-to-host mass ratios than their gaseous counterparts. RPS can act on jellyfish galaxies over long time-scales of ≈1.5-8 Gyr. Jellyfish in more massive hosts are impacted by RPS for a shorter time span and, at a fixed host mass, jellyfish with less cold gas at infall and lower stellar masses at z = 0 have shorter RPS time spans. While RPS may act for long periods of time, the peak RPS period - where at least 50 per cent of the total RPS occurs - begins within ≈1 Gyr of infall and lasts 2 Gyr. During this period, the jellyfish are at host-centric distances ∼0.2-2R200c, illustrating that much of RPS occurs at large distances from the host galaxy. Interestingly, jellyfish continue forming stars until they have lost ≈98 per cent of their cold gas. For groups and clusters in TNG50, jellyfish galaxies deposit more cold gas () into haloes than what exists in them at z = 0, demonstrating that jellyfish, and in general satellite galaxies, are a significant source of cold gas accretion.

Original languageAmerican English
Pages (from-to)3502-3525
Number of pages24
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - 1 Sep 2023

Bibliographical note

Funding Information:
DN and MA acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) through an Emmy Noether Research Group (grant number NE 2441/1-1).

Funding Information:
GJ acknowledges funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 818085 GMGalaxies.

Funding Information:
This publication uses data generated via the platform, development of which is funded by generous support, including a Global Impact Award from Google, and by a grant from the Alfred P. Sloan Foundation. We wish to extend our thanks to the team at Zooniverse with their advice and assistance in building and running this project. We also thank the thousands of volunteers who invested their time and effort to assist us in this project.

Publisher Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.


  • galaxies: clusters: intracluster medium
  • galaxies: evolution
  • galaxies: formation
  • galaxies: haloes
  • galaxies: interactions
  • methods: numerical


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