Abstract
One important result from recent large integral field spectrograph (IFS) surveys is that the intrinsic velocity dispersion of galaxies traced by star-forming gas increases with redshift. Massive, rotation-dominated discs are already in place at z ∼ 2, but they are dynamically hotter than spiral galaxies in the local Universe. Although several plausible mechanisms for this elevated velocity dispersion (e.g. star formation feedback, elevated gas supply, or more frequent galaxy interactions) have been proposed, the fundamental driver of the velocity dispersion enhancement at high redshift remains unclear. We investigate the origin of this kinematic evolution using a suite of cosmological simulations from the FIRE (Feedback In Realistic Environments) project. Although IFS surveys generally cover a wider range of stellar masses than in these simulations, the simulated galaxies show trends between intrinsic velocity dispersion (σ intr ), SFR, and z in agreement with observations. In both observations and simulations, galaxies on the star-forming main sequence have median σ intr values that increase from z ∼ 0 to z ∼ 1–1.5, but this increasing trend is less evident at higher redshift. In the FIRE simulations, σ intr can vary significantly on time-scales of 100 Myr. These variations closely mirror the time evolution of the SFR and gas inflow rate (M gas ). By cross-correlating pairs of σ intr, M gas, and SFR, we show that increased gas inflow leads to subsequent enhanced star formation, and enhancements in σ intr tend to temporally coincide with increases in M gas and SFR.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5125-5137 |
| Number of pages | 13 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 482 |
| Issue number | 4 |
| DOIs | |
| State | Published - Feb 1 2019 |
Funding
We thank J. Stott, M. Swinbank, C. Mason, O. Turner, and N. Leethochawalit for kindly sharing their measurements of galaxy properties. We thank the referee for her/his constructive comments that have helped us to improve the quality of this paper. C-LH acknowledges support from the Harlan J. Smith Fellowship at the University of Texas at Austin. The Flatiron Institute is supported by the Simons Foundation. TY acknowledges fellowship support from the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. CAFG was supported by NSF through grants AST-1412836, AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant NNX15AB22G, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. DK was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. AW was supported by NASA through grants HST-GO-14734 and HST-AR-15057 from STScI. The numerical calculations were run on the Caltech compute cluster ‘Zwicky’ (NSF MRI award #PHY-0960291), allocations TG-AST120025 and TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF, and allocation PRAC NSF.1713353 supported by the NSF. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper. URL: http://www.tacc.utexas.edu.
Keywords
- Galaxies: evolution
- Galaxies: kinematics and dynamics
- Galaxies: structure
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science