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Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function

Deason, Alis J; Koposov, Sergey E; Fattahi, Azadeh; Grand, Robert JJ

Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function Thumbnail


Authors

Sergey E Koposov

Robert JJ Grand



Abstract

Accreted stellar populations are comprised of the remnants of destroyed galaxies, and often dominate the ‘stellar haloes’ of galaxies such as the Milky Way (MW). This ensemble of external contributors is a key indicator of the past assembly history of a galaxy. We introduce a novel statistical method that uses the unbinned metallicity distribution function (MDF) of a stellar population to estimate the mass spectrum of its progenitors. Our model makes use of the well-known mass–metallicity relation of galaxies and assumes Gaussian MDF distributions for individual progenitors: the overall MDF is thus a mixture of MDFs from smaller galaxies. We apply the method to the stellar halo of the MW, as well as the classical MW satellite galaxies. The stellar components of the satellite galaxies have relatively small sample sizes, but we do not find any evidence for accreted populations with L > Lhost/100. We find that the MW stellar halo has N ∼ 1−3 massive progenitors (L ≳ 108L⊙) within 10 kpc, and likely several hundred progenitors in total. We also test our method on simulations of MW-mass haloes, and find that our method is able to recover the true accreted population within a factor of 2. Future data sets will provide MDFs with orders of magnitude more stars, and this method could be a powerful technique to quantify the accreted populations down to the ultra-faint dwarf mass scale for both the MW and its satellites.

Citation

Deason, A. J., Koposov, S. E., Fattahi, A., & Grand, R. J. (2023). Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function. Monthly Notices of the Royal Astronomical Society, 520(4), 6091-6103. https://doi.org/10.1093/mnras/stad535

Journal Article Type Article
Acceptance Date Feb 14, 2023
Online Publication Date Feb 20, 2023
Publication Date 2023
Deposit Date May 10, 2023
Publicly Available Date May 10, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 520
Issue 4
Pages 6091-6103
DOI https://doi.org/10.1093/mnras/stad535
Public URL https://durham-repository.worktribe.com/output/1173195

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.






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