Exploring lenticular galaxy formation in field environments using NewHorizon: evidence for counter-rotating gas accretion as a formation channel

Seongbong Han; J. K. Jang; Emanuele Contini; Yohan Dubois; Seyoung Jeon; Sugata Kaviraj; Taysun Kimm; Katarina Kraljic; Sree Oh; Sebastien Peirani; Christophe Pichon; Sukyoung K. Yi

arXiv · 2411.05910

Exploring lenticular galaxy formation in field environments using NewHorizon: evidence for counter-rotating gas accretion as a formation channel

Seongbong Han·J. K. Jang·Emanuele Contini·Yohan Dubois·Seyoung Jeon·Sugata Kaviraj·Taysun Kimm·Katarina Kraljic·Sree Oh·Sebastien Peirani·Christophe Pichon·Sukyoung K. Yi

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Abstract

The formation pathways of lenticular galaxies (S0s) in field environments remain a matter of debate. We utilize the cosmological hydrodynamic simulation, NewHorizon, to investigate the issue. We select two massive star-formation quenched S0s as our main sample. By closely tracing their physical and morphological evolution, we identify two primary formation channels: mergers and counter-rotating gas accretion. The former induces central gas inflow due to gravitational and hydrodynamic torques, triggering active central star formation which quickly depletes the gas of the galaxy. Counter-rotating gas accretion overall has a similar outcome but more exclusively through hydrodynamic collisions between the pre-existing and newly-accreted gas. Both channels lead to S0 morphology, with gas angular momentum cancellation being a crucial mechanism. These formation pathways quench star formation on a short timescale (< Gyr) compared to the timescales of environmental effects. We also discuss how counter-rotating gas accretion may explain the origin of S0s with ongoing star formation and the frequently observed gas-star misaligned kinematics in S0s.

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Seongbong Han, J. K. Jang, Emanuele Contini, Yohan Dubois, Seyoung Jeon, Sugata Kaviraj, Taysun Kimm, Katarina Kraljic, Sree Oh, Sebastien Peirani, Christophe Pichon, Sukyoung K. Yi. 2024-11-08. Exploring lenticular galaxy formation in field environments using NewHorizon: evidence for counter-rotating gas accretion as a formation channel. https://arxiv.org/abs/2411.05910

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