Abstract
Recent spatially resolved observations of galaxies at z ∼ 0.6-3 reveal that high-redshift galaxies show complex kinematics and a broad distribution of gas-phase metallicity gradients. To understand these results, we use a suite of high-resolution cosmological zoom-in simulations from the Feedback in Realistic Environments project, which include physically motivated models of the multiphase interstellar medium, star formation and stellar feedback. Our simulations reproduce the observed diversity of kinematic properties and metallicity gradients, broadly consistent with observations at z ∼ 0-3. Strong negative metallicity gradients only appear in galaxies with a rotating disc, but not all rotationally supported galaxies have significant gradients. Strongly perturbed galaxies with little rotation always have flat gradients. The kinematic properties and metallicity gradient of a high-redshift galaxy can vary significantly on short time-scales, associated with starburst episodes. Feedback from a starburst can destroy the gas disc, drive strong outflows and flatten a pre-existing negative metallicity gradient. The time variability of a single galaxy is statistically similar to the entire simulated sample, indicating that the observed metallicity gradients in high-redshift galaxies reflect the instantaneous state of the galaxy rather than the accretion and growth history on cosmological time-scales. We find weak dependence of metallicity gradient on stellar mass and specific star formation rate (sSFR). Low-mass galaxies and galaxies with high sSFR tend to have flat gradients, likely due to the fact that feedback is more efficient in these galaxies. We argue that it is important to resolve feedback on small scales in order to produce the diverse metallicity gradients observed.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4780-4794 |
| Number of pages | 15 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 466 |
| Issue number | 4 |
| DOIs | |
| State | Published - May 1 2017 |
Funding
We thank Nicha Leethochawalit, Tucker Jones, Richard Ellis, Xin Wang and Tommaso Treu for insightful discussions and Nicha Leethochawalit for providing a compilation of observational data. We also acknowledge the anonymous referee for helpful suggestions on clarifying the manuscript. The simulations used in this paper were run on XSEDE computational resources (allocations TG-AST120025, TG-AST130039, TG-AST140023 and TG-AST150045) and computational resources provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center (proposal SMD-14-5492 and SMD-15-5950). The analysis was performed on the Caltech compute cluster 'Zwicky' (NSF MRI award #PHY-0960291). 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. RF was supported in part by NASA through Hubble Fellowship grant HF2-51304.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555, in part by the Theoretical Astrophysics Center at UC Berkeley, and by NASA ATP grant 12-ATP-120183. CAFG was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G and by STScI through grant HST-AR-14293.001-A. DK was supported by NSF grant AST-1412153 and Cottrell Scholar Award from the Research Corporation for Science Advancement.
Keywords
- Cosmology: theory
- Galaxies: evolution
- Galaxies: formation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science