The origin of kinematically distinct cores and misaligned gas discs in galaxies from cosmological simulations

Abstract

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 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 ($\approx 6$ 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 $\sim 1/10$) 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 under-appreciated in the past, and large, high-resolution cosmological simulations will be necessary to gain a better understanding in this area.

13 pages, 10 figures. Accepted for publication in MNRAS

References in corpus (18)

• Galactic chemical evolution: Carbon through Zinc
• The SAURON project -- IX. A kinematic classification for early-type galaxies
• SDSS-IV MaNGA IFS Galaxy Survey --- Survey Design, Execution, and Initial Data Quality
• The MASSIVE Survey - I. A Volume-Limited Integral-Field Spectroscopic Study of the Most Massive Early-Type Galaxies within 108 Mpc
• The SAURON project - XII. Kinematic substructures in early-type galaxies: evidence for disks in fast rotators
• Simulations of Cosmic Chemical Enrichment
• The SAURON project - VIII. OASIS/CFHT integral-field spectroscopy of elliptical and lenticular galaxy centres
• The SAGES Legacy Unifying Globulars and GalaxieS Survey (SLUGGS): Sample definition, methods, and initial results
• 2-Dimensional Kinematics of Simulated Disc Merger Remnants
• Formation of massive protostars in atomic cooling haloes
• SDSS-IV MaNGA: Properties of galaxies with kinematically decoupled stellar and gaseous components
• Probing the Physics of Narrow Line Regions in Active Galaxies II: The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7)
• The Effects of AGN Feedback on Present-Day Galaxy Properties in Cosmological Simulations
• Seeding Black Holes in Cosmological Simulations
• The Metallicity and Elemental Abundance Gradients of Simulated Galaxies, and their Environmental Dependence
• Probing the Physics of Narrow Line Regions in Active Galaxies IV: Full data release of The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7)
• Time Evolution of Galaxy Scaling Relations in Cosmological Simulations
• Star Formation in Simulated Galaxies: Understanding the Transition to Quiescence at $3\times 10^{10}$ M${}_{\odot }$

Cited by in corpus (21)

• The role of mergers in driving morphological transformation over cosmic time
• Mysterious Coherence in Several-Megaparsec Scales Between Galaxy Rotation and Neighbor Motion
• SDSS-IV MaNGA: Integral-field kinematics and stellar population of a sample of galaxies with counter-rotating stellar disks selected from about 4000 galaxies
• SDSS-IV MaNGA: Global Properties of Kinematically Misaligned Galaxies
• An increase in black hole activity in galaxies with kinematically misaligned gas
• SDSS-IV MaNGA : spatial resolved properties of kinematically misaligned galaxies
• Galaxy Rotation Coherent with the Motions of Neighbors: Discovery of Observational Evidence
• External gas accretion provides a fresh gas supply to the active S0 galaxy NGC 5077
• Galaxies with kinematically distinct cores in Illustris
• Deep optical imaging of the dark galaxy candidate AGESVC1 282
• Atomic Hydrogen Clues to the Formation of Counterrotating Stellar Discs
• The detection of a massive chain of dark HI clouds in the GAMA G23 Field
• The metallicity and elemental abundance maps of kinematically atypical galaxies for constraining minor merger and accretion histories
• The Origin of Star Formation in Early-type Galaxies Inferred from Spatially Resolved Spectroscopy
• Dust Grain Growth & Dusty Supernovae in Low-Metallicity Molecular Clouds
• The effects of the orbital configurations of mergers on reshaping galaxy structures
• Spatially Resolved Properties of Galaxies with a Kinematically Distinct Core
• Kinematic misalignment as a driver of black hole activity in galaxies with external interactions
• Emergence of red, star-forming galaxies (red misfits) in a ΛCDM universe
• Free-floating molecular clumps and gas mixing: hydrodynamic aftermaths of the intracluster$-$interstellar medium interaction
• HII versus HI in the `green valley' galaxies: direct comparison