Jellyfish galaxies with the IllustrisTNG simulations - I. Gas-stripping phenomena in the full cosmological context

Kiyun Yun*, Annalisa Pillepich, Elad Zinger, Dylan Nelson, Martina Donnari, Gandhali Joshi, Vicente Rodriguez-Gomez, Shy Genel, Rainer Weinberger, Mark Vogelsberger, Lars Hernquist

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


We use the IllustrisTNG simulations to study the demographics and properties of jellyfish galaxies in the full cosmological context. By jellyfish galaxies, we mean satellites orbiting in massive groups and clusters that exhibit highly asymmetric distributions of gas and gas tails. In particular, we select TNG100 galaxies at low redshifts (z ≤ 0.6) with stellar mass exceeding 109.5 M and with host halo masses in the range 1013 ≤ M200c/M ≤ 1014.6. Among more than about 6000 (2600) galaxies with stars (and some gas), we identify 800 jellyfish galaxies by visually inspecting their gas and stellar mass maps in random projections. Namely, about 31 per cent of cluster satellites are found with signatures of ram-pressure stripping and gaseous tails stemming from their main luminous bodies. This is a lower limit: the random orientation entails a loss of about 30 per cent of galaxies that in an optimal projection would otherwise be identified as jellyfish. Furthermore, jellyfish galaxies are more frequent at intermediate and large cluster-centric distances (r/R200c 0.25), in more massive hosts and at smaller satellite masses, and they typically orbit supersonically. The gaseous tails usually extend in opposite directions to the galaxy trajectory, with no relation between tail orientation and position of the host's centre. Finally, jellyfish galaxies are late infallers (<2.5-3 Gyr ago, at z = 0) and the emergence of gaseous tails correlates well with the presence of bow shocks in the intracluster medium.

Original languageAmerican English
Pages (from-to)1042-1066
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 11 Feb 2019
Externally publishedYes

Bibliographical note

Funding Information:
The authors would like to thank Benedetta Vulcani, Bianca Pog-gianti, and Michele Fumagalli for helpful comments on a draft version of this paper and Yen-Ting Lin for useful conversations. It is also a pleasure to thank all the participants of the Ringberg workshop on ‘Galaxy Evolution in Groups and Clusters at ‘low’ Redshift, 2017’ for inspiring exchanges. SG through the Flatiron Institute is supported by the Simons Foundation. MV acknowledges support through an MIT RSC award, the support of the Alfred P. Sloan Foundation, and support by NASA ATP grant NNX17AG29G. The flagship simulations of the IllustrisTNG project used in this work have been run on the HazelHen Cray XC40-system at the High Performance Computing Center Stuttgart as part of project GCS-ILLU of the Gauss centres for Supercomputing (GCS). Ancillary and test runs of the project were also run on the Stampede supercomputer at TACC/XSEDE (allocation AST140063), at the Hydra and Draco supercomputers at the Max Planck Computing and Data Facility, and on the MIT/Harvard computing facilities supported by FAS and MIT MKI.

Publisher Copyright:
© 2018 The Author(s).


  • Cosmology: theory
  • Galaxies: clusters: general
  • Galaxies: clusters: intracluster medium
  • Galaxies: evolution
  • Galaxies: groups: general
  • Methods: numerical


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