TY - JOUR
T1 - Swirls of FIRE
T2 - Spatially resolved gas velocity dispersions and star formation rates in FIRE-2 disc environments
AU - Orr, Matthew E.
AU - Hayward, Christopher C.
AU - Medling, Anne M.
AU - Gurvich, Alexander B.
AU - Hopkins, Philip F.
AU - Murray, Norman
AU - Pineda, Jorge L.
AU - Faucher-Giguère, Claude André
AU - Kereš, Dušan
AU - Wetzel, Andrew
AU - Su, Kung Yi
N1 - Funding Information:
from the NSF Grant AST-1412153 and Cottrell Scholar Award from the Research Corporation for Science Advancement. EQ was supported by NASA ATP grant 12-ATP12-0183, a Simons Investigator award from the Simons Foundation, and the David and Lucile Packard Foundation. AW received support from NASA, through ATP grant 80NSSC18K1097 and HST grants GO-14734 and AR-15057 from STScI, the Heising-Simons Foundation, and a Hellman Foundation Fellowship.
Funding Information:
MEO is grateful for the encouragement of his late father, SRO, in studying astrophysics, and is supported by the National Science Foundation Graduate Research Fellowship under grant no. 1144469. The authors are grateful to the referee for their comments and providing useful suggestions. The Flatiron Institute is supported by the Simons Foundation. Support for AMM is provided by NASA through Hubble Fellowship grant #HST-HF2-51377 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Support for PFH was provided by an Alfred P. Sloan Foundation Research Fellowship, NASA ATP grant NNX14AH35G, and NSF Collaborative Research grant #1411920 and CAREER grant #1455342. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by 〈0:funding-source 3:href="http://dx.doi.o rg/10.13039/100000104"〉NASA〈/0:funding-source〉 through grant 17-ATP17-0067, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. DK acknowledges support
Publisher Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2020
Y1 - 2020
N2 - We study the spatially resolved (sub-kpc) gas velocity dispersion (σ)-star formation rate (SFR) relation in the FIRE-2 (Feedback in Realistic Environments) cosmological simulations. We specifically focus on Milky Way-mass disc galaxies at late times (z ≈ 0). In agreement with observations, we find a relatively flat relationship, with σ ≈ 15-30 km s−1 in neutral gas across 3 dex in SFRs. We show that higher dense gas fractions (ratios of dense gas to neutral gas) and SFRs are correlated at constant σ. Similarly, lower gas fractions (ratios of gas to stellar mass) are correlated with higher σ at constant SFR. The limits of the σ-ΣSFR relation correspond to the onset of strong outflows. We see evidence of 'on-off' cycles of star formation in the simulations, corresponding to feedback injection time-scales of 10-100 Myr, where SFRs oscillate about equilibrium SFR predictions. Finally, SFRs and velocity dispersions in the simulations agree well with feedback-regulated and marginally stable gas disc (Toomre's Q = 1) model predictions, and the simulation data effectively rule out models assuming that gas turns into stars at (low) constant efficiency (i.e. 1 per cent per free-fall time). And although the simulation data do not entirely exclude gas accretion/gravitationally powered turbulence as a driver of σ, it appears to be subdominant to stellar feedback in the simulated galaxy discs at z ≈ 0.
AB - We study the spatially resolved (sub-kpc) gas velocity dispersion (σ)-star formation rate (SFR) relation in the FIRE-2 (Feedback in Realistic Environments) cosmological simulations. We specifically focus on Milky Way-mass disc galaxies at late times (z ≈ 0). In agreement with observations, we find a relatively flat relationship, with σ ≈ 15-30 km s−1 in neutral gas across 3 dex in SFRs. We show that higher dense gas fractions (ratios of dense gas to neutral gas) and SFRs are correlated at constant σ. Similarly, lower gas fractions (ratios of gas to stellar mass) are correlated with higher σ at constant SFR. The limits of the σ-ΣSFR relation correspond to the onset of strong outflows. We see evidence of 'on-off' cycles of star formation in the simulations, corresponding to feedback injection time-scales of 10-100 Myr, where SFRs oscillate about equilibrium SFR predictions. Finally, SFRs and velocity dispersions in the simulations agree well with feedback-regulated and marginally stable gas disc (Toomre's Q = 1) model predictions, and the simulation data effectively rule out models assuming that gas turns into stars at (low) constant efficiency (i.e. 1 per cent per free-fall time). And although the simulation data do not entirely exclude gas accretion/gravitationally powered turbulence as a driver of σ, it appears to be subdominant to stellar feedback in the simulated galaxy discs at z ≈ 0.
KW - Galaxies: ISM
KW - Galaxies: evolution
KW - Galaxies: kinematics and dynamics
KW - Galaxies: spiral
KW - Galaxies: star formation
KW - ISM: kinematics and dynamics
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U2 - 10.1093/MNRAS/STAA1619
DO - 10.1093/MNRAS/STAA1619
M3 - Article
AN - SCOPUS:85095722370
SN - 0035-8711
VL - 496
SP - 1620
EP - 1637
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -