The Origin of r -process Enhanced Metal-poor Halo Stars In Now-destroyed Ultra-faint Dwarf Galaxies
Name
Brauer_2019_ApJ_871_247.pdf
Description
Published version
Size
862.35 KB
Format
Adobe PDF
Checksum (MD5)
ffcc1207f2d3af9649e7fc790162994a
Author(s)
Brauer, Kaley
Frebel, Anna L.
Date Issued
February 2019
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Citation
Brauer, Kaley et al. “The Origin of r -process Enhanced Metal-poor Halo Stars In Now-destroyed Ultra-faint Dwarf Galaxies.” Astrophysical Journal, 87, 2 (February 2019): 247 © 2019 The Author(s)
Version
Final published version
Abstract
The highly r-process-enhanced (r-II) metal-poor halo stars we observe today could play a key role in understanding early ultra-faint dwarf galaxies (UFDs), the smallest building blocks of the Milky Way. If a significant fraction of metal-poor r-II halo stars originated in the UFDs that merged to help form the Milky Way, observations of r-II stars could help us study these now-destroyed systems and probe the formation history of our Galaxy. To conduct our initial investigation into this possible connection, we use high-resolution cosmological simulations of Milky Way-mass galaxies from the Caterpillar suite in combination with a simple, empirically motivated treatment of r-process enrichment. We determine the fraction of metal-poor halo stars that could have formed from highly r-process-enhanced gas in now-destroyed low-mass UFDs, the simulated r-II fraction, and compare it to the "as observed" r-II fraction. We find that the simulated fraction, f r-II,sim ∼ 1%-2%, can account for around half of the "as observed" fraction, f r-II,obs ∼ 2%-4%. The "as observed" fraction likely overrepresents the fraction of r-II stars due to incomplete sampling, though, meaning f r-II,sim likely accounts for more than half of the true f r-II,obs . Further considering some parameter variations and scatter between individual simulations, the simulated fraction can account for around 20%-80% of the "as observed" fraction.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/1538-4357/AAFAFB
