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Simulating Metal Mixing of Both Common and Rare Enrichment Sources in a Low-mass Dwarf Galaxy

Emerick, Andrew and Bryan, Greg L. and Mac Low, Mordecai-Mark (2020) Simulating Metal Mixing of Both Common and Rare Enrichment Sources in a Low-mass Dwarf Galaxy. Astrophysical Journal, 890 (2). Art. No. 155. ISSN 1538-4357. https://resolver.caltech.edu/CaltechAUTHORS:20200225-135943724

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Abstract

One-zone models constructed to match observed stellar abundance patterns have been used extensively to constrain the sites of nucleosynthesis with sophisticated libraries of stellar evolution and stellar yields. The metal mixing included in these models is usually highly simplified, although it is likely to be a significant driver of abundance evolution. In this work we use high-resolution hydrodynamics simulations to investigate how metals from individual enrichment events with varying source energies E_(ej) mix throughout the multiphase interstellar medium (ISM) of a low-mass (M_(gas) = 2 × 10⁶ M_⊙), low-metallicity, isolated dwarf galaxy. These events correspond to the characteristic energies of both common and exotic astrophysical sites of nucleosynthesis, including asymptotic giant branch winds (E_(ej) ~ 10⁴⁶ erg), neutron star–neutron star mergers (E_(ej) ~ 10⁴⁹ erg), supernovae (E_(ej) ~ 10⁵¹ erg), and hypernovae (E_(ej) ~ 10⁵² erg). We find the mixing timescales for individual enrichment sources in our dwarf galaxy to be long (100 Myr–1 Gyr), with a clear trend of increasing homogeneity for the more energetic events. Given these timescales, we conclude that the spatial distribution and frequency of events are important drivers of abundance homogeneity on large scales; rare, low-E_(ej) events should be characterized by particularly broad abundance distributions. The source energy E_(ej) also correlates with the fraction of metals ejected in galactic winds, ranging anywhere from 60% at the lowest energy to 95% for hypernovae. We conclude by examining how the radial position, local ISM density, and global star formation rate influence these results.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ab6efcDOIArticle
https://arxiv.org/abs/1909.04695arXivDiscussion Paper
ORCID:
AuthorORCID
Emerick, Andrew0000-0003-2807-328X
Bryan, Greg L.0000-0003-2630-9228
Mac Low, Mordecai-Mark0000-0003-0064-4060
Additional Information:© 2020. The American Astronomical Society. Received 2019 September 9; revised 2020 January 3; accepted 2020 January 18; published 2020 February 25. We would like to thank Brian O'Shea, Benoit Côté, Kathryn V. Johnston, and Jason Tumlinson for valuable discussions and comments on a previous version of this work that appeared as a chapter in the first author's dissertation. In addition, we thank the anonymous referee, whose comments have significantly improved this work. A.E. was supported by a Blue Waters Graduate Fellowship. G.L.B. acknowledges support from NSF grants AST-1615955 and OAC-1835509 and NASA grant NNX15AB20G. M.-M.M.L. was partly supported by NSF grant AST18-15461. We gratefully recognize computational resources provided by NSF XSEDE through grant No. TGMCA99S024, the NASA High-End Computing Program through the NASA Advanced Supercomputing Division at Ames Research Center, Columbia University, and the Flatiron Institute. This work made significant use of many open-source software packages. These are products of collaborative effort by many independent developers from numerous institutions around the world. Their commitment to open science has helped make this work possible. Software: yt (Turk et al. 2011), Enzo (Bryan et al. 2014), Grackle (Smith et al. 2017), Python (Van Rossum & Drake 1995), IPython (Pérez & Granger 2007), NumPy (Oliphant 2006), SciPy (Virtanen et al. 2020), Matplotlib (Hunter 2007), HDF5 (The HDF Group 1997), h5py (Collette et al. 2017), Astropy (Astropy Collaboration et al. 2013; Price-Whelan et al. 2018), Cloudy (Ferland et al. 2013), and deepdish.
Group:TAPIR
Funders:
Funding AgencyGrant Number
Blue Waters Graduate FellowshipUNSPECIFIED
NSFAST-1615955
NSFOAC-1835509
NASANNX15AB20G
NSFAST-1815461
NSFTG-MCA99S024
Subject Keywords:Galaxy chemical evolution ; Dwarf galaxies ; Chemical enrichment ; Hydrodynamics
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Galaxy chemical evolution (580); Dwarf galaxies (416); Chemical enrichment (225); Hydrodynamics (1963)
Record Number:CaltechAUTHORS:20200225-135943724
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200225-135943724
Official Citation:Andrew Emerick et al 2020 ApJ 890 155
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101548
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:26 Feb 2020 15:55
Last Modified:26 Feb 2020 15:55

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