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Published August 11, 2015 | Submitted + Published
Journal Article Open

The creation and persistence of a misaligned gas disc in a simulated early-type galaxy

Abstract

Massive early-type galaxies (ETGs) commonly have gas discs which are kinematically misaligned with the stellar component. These discs feel a torque from the stars and the angular momentum vectors are expected to align quickly. We present results on the evolution of a misaligned gas disc in a cosmological simulation of a massive ETG from the feedback in realistic environments project. This galaxy experiences a merger which, together with a strong galactic wind, removes most of the original gas disc. The galaxy subsequently reforms a gas disc through accretion of cold gas, but it is initially 120° misaligned with the stellar rotation axis. This misalignment persists for about 2 Gyr before the gas–star misalignment angle drops below 20°. The time it takes for the gaseous and stellar components to align is much longer than previously thought, because the gas disc is accreting a significant amount of mass for about 1.5 Gyr after the merger, during which the angular momentum change induced by accreted gas dominates over that induced by stellar torques. Once the gas accretion rate has decreased sufficiently, the gas disc decouples from the surrounding halo gas and realigns with the stellar component in about six dynamical times. During the late evolution of the misaligned gas disc, the centre aligns faster than the outskirts, resulting in a warped disc. We discuss the observational consequences of the long survival of our misaligned gas disc and how our results can be used to calibrate merger rate estimates from observed gas misalignments.

Additional Information

© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 May 27. Received 2015 May 26. In original form 2015 April 14. First published online June 22, 2015. We would like to thank the referee for valuable comments. FvdV would like to thank Ann-Marie Madigan, Mariska Kriek, Chung-Pei Ma, and Sanch Borthakur for useful discussions. TAD acknowledges support from a Science and Technology Facilities Council Ernest Rutherford Fellowship. DK was supported in part by NSF grant AST-1412153 and funds from the University of California San Diego. EQ was supported in part by NASA ATP grant 12-APT12- 0183, a Simons Investigator award from the Simons Foundation, and the David and Lucile Packard Foundation. CAFG was supported by NSF through grant AST-1412836 and by Northwestern University funds. The simulation presented here used computational resources granted by the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number OCI-1053575, specifically allocations TG-AST120025 (PI Kereš), TG-AST130039 (PI Hopkins), TG-AST1140023 (PI Faucher-Giguère).

Attached Files

Published - MNRAS-2015-van_de_Voort-3269-77.pdf

Submitted - 1504.03685v1.pdf

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Created:
August 20, 2023
Modified:
October 23, 2023