BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, and POPULATION GRADIENTS in LOW-MASS GALAXIES

Kareem El-Badry; Andrew Wetzel; Marla Geha; Philip F. Hopkins; Dusan Kereš; T. K. Chan; Claude André Faucher-Giguère

doi:10.3847/0004-637X/820/2/131

BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, and POPULATION GRADIENTS in LOW-MASS GALAXIES

Kareem El-Badry, Andrew Wetzel, Marla Geha, Philip F. Hopkins, Dusan Kereš, T. K. Chan, Claude André Faucher-Giguère

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

231 Scopus citations

Abstract

We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (M_star = 2 ×10⁶ - 5 ×10¹⁰ M_o) 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_o, 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.

Original language	English (US)
Article number	131
Journal	Astrophysical Journal
Volume	820
Issue number	2
DOIs	https://doi.org/10.3847/0004-637X/820/2/131
State	Published - Apr 1 2016

Funding

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.

Keywords

galaxies: dwarf
galaxies: evolution
galaxies: kinematics and dynamics
galaxies: star formation

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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@article{f20b0009a22f430a8df77ee1e3ff85ee,

title = "BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, and POPULATION GRADIENTS in LOW-MASS GALAXIES",

abstract = "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.",

keywords = "galaxies: dwarf, galaxies: evolution, galaxies: kinematics and dynamics, galaxies: star formation",

author = "Kareem El-Badry and Andrew Wetzel and Marla Geha and Hopkins, {Philip F.} and Dusan Kere{\v s} and Chan, {T. K.} and Faucher-Gigu{\`e}re, {Claude Andr{\'e}}",

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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

PY - 2016/4/1

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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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BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, and POPULATION GRADIENTS in LOW-MASS GALAXIES

Abstract

Funding

Keywords

ASJC Scopus subject areas

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