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Breathing FIRE: How Stellar Feedback Drives Radial Migration, Rapid Size Fluctuations, and Population Gradients in Low-Mass Galaxies

El-Badry, Kareem and Wetzel, Andrew and Geha, Marla and Hopkins, Philip F. and Kereš, Dušan and Chan, T. K. and Faucher-Giguère, Claude-André (2016) Breathing FIRE: How Stellar Feedback Drives Radial Migration, Rapid Size Fluctuations, and Population Gradients in Low-Mass Galaxies. Astrophysical Journal, 820 (2). Art. No. 131. ISSN 0004-637X. doi:10.3847/0004-637X/820/2/131.

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We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (M_(star) = 2 × 10^6 − 5 × 10^(10) M_⊙) 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 M_(star). 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 M_(star) ≈ 10^(7–9.6) M_⊙, 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
El-Badry, Kareem0000-0002-6871-1752
Wetzel, Andrew0000-0003-0603-8942
Geha, Marla0000-0002-7007-9725
Hopkins, Philip F.0000-0003-3729-1684
Kereš, Dušan0000-0002-1666-7067
Chan, T. K.0000-0003-2544-054X
Faucher-Giguère, Claude-André0000-0002-4900-6628
Additional Information:© 2016 The American Astronomical Society. Received 2015 December 3; accepted 2016 February 23; published 2016 March 30. We thank Jeremy Bradford for sharing observational data and Coral Wheeler and Frank van den Bosch for useful discussions and comments. We also thank the reviewer for helpful comments. K.E. acknowledges support from the Caltech SURF program. A.R.W. gratefully acknowledges support from the Moore Center for Theoretical Cosmology and Physics at Caltech via a Moore Prize Fellowship, and from Carnegie Observatories via a Carnegie Fellowship in Theoretical Astrophysics. 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.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Caltech Moore Center for Theoretical Cosmology and PhysicsUNSPECIFIED
Carnegie ObservatoriesUNSPECIFIED
John S. Guggenheim Memorial FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
University of California, San DiegoUNSPECIFIED
Northwestern UniversityUNSPECIFIED
Subject Keywords:galaxies: dwarf; galaxies: evolution; galaxies: kinematics and dynamics; galaxies: star formation
Issue or Number:2
Record Number:CaltechAUTHORS:20160510-102001148
Persistent URL:
Official Citation:Kareem El-Badry et al 2016 ApJ 820 131
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66876
Deposited By: Ruth Sustaita
Deposited On:10 May 2016 19:06
Last Modified:11 Nov 2021 00:23

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