Formation of a Malin 1 analogue in IllustrisTNG by stimulated accretion

Qirong Zhu, Dandan Xu, Massimo Gaspari, Vicente Rodriguez-Gomez, Dylan Nelson, Mark Vogelsberger, Paul Torrey, Annalisa Pillepich, Jolanta Zjupa, Rainer Weinberger, Federico Marinacci, Rüdiger Pakmor, Shy Genel, Yuexing Li, Volker Springel, Lars Hernquist

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25 Scopus citations


The galaxy Malin 1 contains the largest stellar disc known but the formation mechanism of this structure has been elusive. In this paper, we report a Malin 1 analogue in the 100 Mpc IllustrisTNG simulation and describe its formation history. At redshift zero, this massive galaxy, having a maximum circular velocity Vmax of 430 km s-1, contains a 100 kpc gas/stellar disc with morphology similar toMalin 1. The simulated galaxy reproduces well many observed features of Malin 1's vast disc, including its stellar ages, metallicities, and gas rotation curve. We trace the extended disc back in time and find that a large fraction of the cold gas at redshift zero originated from the cooling of hot halo gas, triggered by the merger of a pair of intruding galaxies. Our finding provides a novel way to form large galaxy discs as extreme as Malin 1 within the current galaxy formation framework.

Original languageEnglish (US)
Pages (from-to)L18-L22
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Oct 11 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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