TY - JOUR
T1 - The origin of kinematically distinct cores and misaligned gas discs in galaxies from cosmological simulations
AU - Taylor, Philip
AU - Federrath, Christoph
AU - Kobayashi, Chiaki
N1 - Publisher Copyright:
© 2018 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - Integral field spectroscopy surveys provide spatially resolved gas and stellar kinematics of galaxies. They have unveiled a range of atypical kinematic phenomena, which require detailed modelling to understand. We present results from a cosmological simulation that includes stellar and active galactic nucleus (AGN) feedback. We find that the distribution of angles between the gas and stellar angular momenta of galaxies is not affected by projection effects. We examine five galaxies (≈6 per cent of well resolved galaxies) that display atypical kinematics; two of the galaxies have kinematically distinct cores (KDC), while the other three have counter-rotating gas and stars. All five form the majority of their stars in the field, subsequently falling into cosmological filaments where the relative orientation of the stellar angular momentum and the bulk gas flow leads to the formation of a counter-rotating gas disc. The accreted gas exchanges angular momentum with pre-existing co-rotating gas causing it to fall to the centre of the galaxy. This triggers low-level AGN feedback, which reduces star formation. Later, two of the galaxies experience a minor merger (stellar mass ratio ~1/10) with a galaxy on a retrograde orbit compared to the spin of the stellar component of the primary. This produces the KDCs, and is a different mechanism than suggested by other works. The role of minor mergers in the kinematic evolution of galaxies may have been underappreciated in the past, and large, high-resolution cosmological simulations will be necessary to gain a better understanding in this area.
AB - Integral field spectroscopy surveys provide spatially resolved gas and stellar kinematics of galaxies. They have unveiled a range of atypical kinematic phenomena, which require detailed modelling to understand. We present results from a cosmological simulation that includes stellar and active galactic nucleus (AGN) feedback. We find that the distribution of angles between the gas and stellar angular momenta of galaxies is not affected by projection effects. We examine five galaxies (≈6 per cent of well resolved galaxies) that display atypical kinematics; two of the galaxies have kinematically distinct cores (KDC), while the other three have counter-rotating gas and stars. All five form the majority of their stars in the field, subsequently falling into cosmological filaments where the relative orientation of the stellar angular momentum and the bulk gas flow leads to the formation of a counter-rotating gas disc. The accreted gas exchanges angular momentum with pre-existing co-rotating gas causing it to fall to the centre of the galaxy. This triggers low-level AGN feedback, which reduces star formation. Later, two of the galaxies experience a minor merger (stellar mass ratio ~1/10) with a galaxy on a retrograde orbit compared to the spin of the stellar component of the primary. This produces the KDCs, and is a different mechanism than suggested by other works. The role of minor mergers in the kinematic evolution of galaxies may have been underappreciated in the past, and large, high-resolution cosmological simulations will be necessary to gain a better understanding in this area.
KW - Galaxies: evolution
KW - Galaxies: kinematics and dynamics
KW - Methods: numerical
UR - http://www.scopus.com/inward/record.url?scp=85051561338&partnerID=8YFLogxK
U2 - 10.1093/mnras/sty1439
DO - 10.1093/mnras/sty1439
M3 - Article
SN - 0035-8711
VL - 479
SP - 141
EP - 152
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -