TY - JOUR
T1 - BREATHING FIRE
T2 - HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, and POPULATION GRADIENTS in LOW-MASS GALAXIES
AU - El-Badry, Kareem
AU - Wetzel, Andrew
AU - Geha, Marla
AU - Hopkins, Philip F.
AU - Kereš, Dusan
AU - Chan, T. K.
AU - Faucher-Giguère, Claude André
N1 - Funding Information:
M.G. acknowledges a fellowship from the John S. Guggenheim Memorial Foundation. Support for P.F.H. was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. D.K. and T.K.C. were supported in part by NSF grant AST-1412153, and funds from the University of California San Diego. C.A.F.G. was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G, and by Northwestern University funds. Numerical calculations were run on the Caltech compute cluster Zwicky (NSF MRI award #PHY-0960291) and on allocations TG-AST120025 and TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF.
Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (Mstar = 2 ×106 - 5 ×1010 Mo) using the Feedback in Realistic Environments (FIRE) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate ∼1 kpc within their first 100 Myr, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies' effective radii can fluctuate by factors of >2 over ∼200 Myr, and these rapid size fluctuations can account for much of the observed scatter in the radius at fixed Mstar. Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes - and even inverts - intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star formation histories from stellar populations at z = 0 can be severely biased. These effects are strongest at Mstar ≈ 107-9.6 Mo, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in ΛCDM.
AB - We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (Mstar = 2 ×106 - 5 ×1010 Mo) using the Feedback in Realistic Environments (FIRE) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate ∼1 kpc within their first 100 Myr, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies' effective radii can fluctuate by factors of >2 over ∼200 Myr, and these rapid size fluctuations can account for much of the observed scatter in the radius at fixed Mstar. Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes - and even inverts - intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star formation histories from stellar populations at z = 0 can be severely biased. These effects are strongest at Mstar ≈ 107-9.6 Mo, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in ΛCDM.
KW - galaxies: dwarf
KW - galaxies: evolution
KW - galaxies: kinematics and dynamics
KW - galaxies: star formation
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U2 - 10.3847/0004-637X/820/2/131
DO - 10.3847/0004-637X/820/2/131
M3 - Article
AN - SCOPUS:84962878596
SN - 0004-637X
VL - 820
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 131
ER -