Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Edge : Dark matter core creation depends on the timing of star formation

Muni, Claudia ; Pontzen, Andrew ; Read, Justin I. ; Agertz, Oscar LU ; Rey, Martin P. LU ; Taylor, Ethan ; Kim, Stacy Y. and Gray, Emily I. (2025) In Monthly Notices of the Royal Astronomical Society 536(1). p.314-323
Abstract

We study feedback-driven cold dark matter core creation in the edge suite of radiation-hydrodynamical dwarf galaxy simulations. Understanding this process is crucial when using observed dwarf galaxies to constrain the particle nature of dark matter. While previous studies have shown that the stellar mass to halo mass ratio (M∗/M200) determines the extent of core creation, we find that in low-mass dwarfs there is a crucial additional effect, namely the timing of star formation relative to reionization. Sustained post-reionization star formation decreases central dark matter density through potential fluctuations; conversely, pre-reionization star formation is too short-lived to have such an effect. In fact, large... (More)

We study feedback-driven cold dark matter core creation in the edge suite of radiation-hydrodynamical dwarf galaxy simulations. Understanding this process is crucial when using observed dwarf galaxies to constrain the particle nature of dark matter. While previous studies have shown that the stellar mass to halo mass ratio (M∗/M200) determines the extent of core creation, we find that in low-mass dwarfs there is a crucial additional effect, namely the timing of star formation relative to reionization. Sustained post-reionization star formation decreases central dark matter density through potential fluctuations; conversely, pre-reionization star formation is too short-lived to have such an effect. In fact, large stellar masses accrued prior to reionization are a strong indicator of early collapse, and therefore indicative of an increased central dark matter density. We parametrize this differentiated effect by considering M∗,post/M∗,pre, where the numerator and denominator represent the stellar mass formed after and before z ∼ 6.5, respectively. Our study covers the halo mass range 109M⊙ < M200 < 1010M⊙ (stellar masses in the range 104M⊙ < M∗ < 108M⊙), spanning both ultra-faint and classical dwarfs. In this regime M∗,post/M∗,pre, correlates almost perfectly with the central dark matter density at z=0, even when including simulations with a substantially different variant of feedback and cooling. We provide fitting formulae to describe the new-found dependence.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
dark matter, galaxies: dwarf, galaxies: haloes
in
Monthly Notices of the Royal Astronomical Society
volume
536
issue
1
pages
10 pages
publisher
Oxford University Press
external identifiers
  • scopus:105033798967
ISSN
0035-8711
DOI
10.1093/mnras/stae2748
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
id
a48fd652-e99a-436c-a8a0-10b3f3c87c41
date added to LUP
2026-07-02 10:15:22
date last changed
2026-07-02 10:16:22
@article{a48fd652-e99a-436c-a8a0-10b3f3c87c41,
  abstract     = {{<p>We study feedback-driven cold dark matter core creation in the edge suite of radiation-hydrodynamical dwarf galaxy simulations. Understanding this process is crucial when using observed dwarf galaxies to constrain the particle nature of dark matter. While previous studies have shown that the stellar mass to halo mass ratio (M<sub>∗</sub>/<sub>M200</sub>) determines the extent of core creation, we find that in low-mass dwarfs there is a crucial additional effect, namely the timing of star formation relative to reionization. Sustained post-reionization star formation decreases central dark matter density through potential fluctuations; conversely, pre-reionization star formation is too short-lived to have such an effect. In fact, large stellar masses accrued prior to reionization are a strong indicator of early collapse, and therefore indicative of an increased central dark matter density. We parametrize this differentiated effect by considering M<sub>∗,post</sub>/M<sub>∗,pre</sub>, where the numerator and denominator represent the stellar mass formed after and before z ∼ 6.5, respectively. Our study covers the halo mass range 10<sup>9</sup>M⊙ &lt; M<sub>200</sub> &lt; 10<sup>10</sup>M⊙ (stellar masses in the range 10<sup>4</sup>M⊙ &lt; M<sub>∗</sub> &lt; 10<sup>8</sup>M⊙), spanning both ultra-faint and classical dwarfs. In this regime M<sub>∗,post</sub>/M<sub>∗,pre</sub>, correlates almost perfectly with the central dark matter density at z=0, even when including simulations with a substantially different variant of feedback and cooling. We provide fitting formulae to describe the new-found dependence.</p>}},
  author       = {{Muni, Claudia and Pontzen, Andrew and Read, Justin I. and Agertz, Oscar and Rey, Martin P. and Taylor, Ethan and Kim, Stacy Y. and Gray, Emily I.}},
  issn         = {{0035-8711}},
  keywords     = {{dark matter; galaxies: dwarf; galaxies: haloes}},
  language     = {{eng}},
  month        = {{01}},
  number       = {{1}},
  pages        = {{314--323}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Edge : Dark matter core creation depends on the timing of star formation}},
  url          = {{http://dx.doi.org/10.1093/mnras/stae2748}},
  doi          = {{10.1093/mnras/stae2748}},
  volume       = {{536}},
  year         = {{2025}},
}