EDGE: Dark matter core creation depends on the timing of star formation
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2024
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| author | Muni, Claudia Pontzen, Andrew Read, Justin I. Agertz, Oscar Rey, Martin P. Taylor, Ethan Kim, Stacy Y. Gray, Emily I. |
| author_facet | Muni, Claudia Pontzen, Andrew Read, Justin I. Agertz, Oscar Rey, Martin P. Taylor, Ethan Kim, Stacy Y. Gray, Emily I. |
| contents | 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 the stellar-mass to halo-mass ratio $(M_{\star} / M_{200})$ 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 reionisation. Sustained post-reionisation star formation decreases central dark matter density through potential fluctuations; conversely, pre-reionisation star formation is too short-lived to have such an effect. In fact, large stellar masses accrued prior to reionisation are a strong indicator of early collapse, and therefore indicative of an increased central dark matter density. We parameterise this differentiated effect by considering $M_{\star,\mathrm{post}}/M_{\star,\mathrm{pre}}$, where the numerator and denominator represent the amount of star formation after and before $z\sim6.5$, respectively. Our study covers the halo mass range $10^9 < M_{200} < 10^{10} M_\odot$ (stellar masses between $10^4 < M_{\star} < 10^8 M_\odot$), spanning both ultra-faint and classical dwarfs. In this regime, $M_{\star,\mathrm{post}}/M_{\star,\mathrm{pre}}$ 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 newfound dependence. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2407_14579 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | EDGE: Dark matter core creation depends on the timing of star formation Muni, Claudia Pontzen, Andrew Read, Justin I. Agertz, Oscar Rey, Martin P. Taylor, Ethan Kim, Stacy Y. Gray, Emily I. Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics 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 the stellar-mass to halo-mass ratio $(M_{\star} / M_{200})$ 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 reionisation. Sustained post-reionisation star formation decreases central dark matter density through potential fluctuations; conversely, pre-reionisation star formation is too short-lived to have such an effect. In fact, large stellar masses accrued prior to reionisation are a strong indicator of early collapse, and therefore indicative of an increased central dark matter density. We parameterise this differentiated effect by considering $M_{\star,\mathrm{post}}/M_{\star,\mathrm{pre}}$, where the numerator and denominator represent the amount of star formation after and before $z\sim6.5$, respectively. Our study covers the halo mass range $10^9 < M_{200} < 10^{10} M_\odot$ (stellar masses between $10^4 < M_{\star} < 10^8 M_\odot$), spanning both ultra-faint and classical dwarfs. In this regime, $M_{\star,\mathrm{post}}/M_{\star,\mathrm{pre}}$ 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 newfound dependence. |
| title | EDGE: Dark matter core creation depends on the timing of star formation |
| topic | Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2407.14579 |