New Horizon: On the Origin of the Stellar Disk and Spheroid of Field Galaxies at z = 0.7

Min Jung Park, Sukyoung K. Yi, Yohan Dubois, Christophe Pichon, Taysun Kimm, Julien Devriendt, Hoseung Choi, Marta Volonteri, Sugata Kaviraj, Sebastien Peirani

Research output: Contribution to journalArticle

Abstract

The origin of the disk and spheroid of galaxies has been a key open question in understanding their morphology Using the high-resolution cosmological simulation New Horizon, we explore kinematically decomposed disk and spheroidal components of 144 field galaxies with masses greater than 109 M at z=0.7. The origins of stellar particles are classified according to their birthplace (in situ or ex situ) and their orbits at birth. Before disk settling, stars form mainly through chaotic mergers between protogalaxies and become part of the spheroidal component. When disk settling starts, we find that more massive galaxies begin to form disk stars from earlier epochs; massive galaxies commence to develop their disks at z1-2, while low-mass galaxies do after z1. The formation of disks is affected by accretion as well, as mergers can trigger gas turbulence or induce misaligned gas infall that hinders galaxies from forming corotating disk stars. The importance of accreted stars is greater in more massive galaxies, especially in developing massive spheroids. A significant fraction of the spheroids come from the disk stars that are perturbed, and this becomes more important at lower redshifts. Some (12.5%) of our massive galaxies develop counter-rotating disks from the gas infall misaligned with the existing disk plane, which can last for more than a gigayear until they become the dominant component and flip the angular momentum of the galaxy in the opposite direction. The final disk-to-total ratio of a galaxy needs to be understood in relation to its stellar mass and accretion history. We quantify the significance of the stars with different origins and provide them as guiding values.

Original languageEnglish
Article number25
JournalAstrophysical Journal
Volume883
Issue number1
DOIs
Publication statusPublished - 2019 Sep 20

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spheroids
horizon
galaxies
merger
accretion
gas
stars
angular momentum
turbulence
settling
history
simulation
gases
protogalaxies
rotating disks
stellar mass
counters
actuators
time measurement
histories

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Park, Min Jung ; Yi, Sukyoung K. ; Dubois, Yohan ; Pichon, Christophe ; Kimm, Taysun ; Devriendt, Julien ; Choi, Hoseung ; Volonteri, Marta ; Kaviraj, Sugata ; Peirani, Sebastien. / New Horizon : On the Origin of the Stellar Disk and Spheroid of Field Galaxies at z = 0.7. In: Astrophysical Journal. 2019 ; Vol. 883, No. 1.
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Park, MJ, Yi, SK, Dubois, Y, Pichon, C, Kimm, T, Devriendt, J, Choi, H, Volonteri, M, Kaviraj, S & Peirani, S 2019, 'New Horizon: On the Origin of the Stellar Disk and Spheroid of Field Galaxies at z = 0.7', Astrophysical Journal, vol. 883, no. 1, 25. https://doi.org/10.3847/1538-4357/ab3afe

New Horizon : On the Origin of the Stellar Disk and Spheroid of Field Galaxies at z = 0.7. / Park, Min Jung; Yi, Sukyoung K.; Dubois, Yohan; Pichon, Christophe; Kimm, Taysun; Devriendt, Julien; Choi, Hoseung; Volonteri, Marta; Kaviraj, Sugata; Peirani, Sebastien.

In: Astrophysical Journal, Vol. 883, No. 1, 25, 20.09.2019.

Research output: Contribution to journalArticle

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