COZMIC. I. Cosmological Zoom-in Simulations with Initial Conditions Beyond Cold Dark Matter

Abstract

We present 72 cosmological dark matter-only $N$-body zoom-in simulations with initial conditions beyond cold, collisionless dark matter (CDM), as the first installment of the COZMIC suite. We simulate Milky Way (MW) analogs with linear matter power spectra $P(k)$ for i) thermal-relic warm dark matter (WDM) with masses $m_{\mathrm{WDM}}\in [3,4,5,6,6.5,10]\mathrm{keV}$, ii) fuzzy dark matter (FDM) with masses $m_{\mathrm{FDM}}\in [25.9,69.4,113,151,185,490]\times 10^{-22}\mathrm{eV}$, and iii) interacting dark matter (IDM) with a velocity-dependent elastic proton scattering cross section $\ddot{I}ƒ=\ddot{I}{ƒ}_0{v}^n$ relative particle velocity scaling $n\in [2,4]$, and dark matter mass $m_{\mathrm{IDM}}\in [10^{-4},10^{-2},1]$ GeV. Subhalo mass function (SHMF) suppression is significantly steeper in FDM versus WDM, while dark acoustic oscillations in $P(k)$ can reduce SHMF suppression for IDM. We fit SHMF models to our simulation results and derive new bounds on WDM and FDM from the MW satellite population, obtaining $m_{\mathrm{WDM}}>5.9\mathrm{keV}$ and $m_{\mathrm{FDM}}>1.4\times 10^{-20}\mathrm{eV}$ at $95\%$ confidence; these limits are $\approx 10\%$ weaker and $5\times$ stronger than previous constraints owing to the updated transfer functions and SHMF models, respectively. We estimate IDM bounds for $n=2$ ($n=4$) and obtain $\ddot{I}{ƒ}_0<1.0\times 10^{-27}$, $1.3\times 10^{-24}$, and $3.1\times 10^{-23}{\mathrm{cm}}^2$ ($\ddot{I}{ƒ}_0<9.9\times 10^{-27}$, $9.8\times 10^{-21}$, and $2.1\times 10^{-17}{\mathrm{cm}}^2$) for $m_{\mathrm{IDM}}=10^{-4}$, $10^{-2}$, and $1$ GeV, respectively. Thus, future development of IDM SHMF models can improve IDM cross section bounds by up to a factor of $\sim 20$ with current data. COZMIC presents an important step toward accurate small-scale structure modeling in beyond-CDM cosmologies, critical to upcoming observational searches for dark matter physics.

36 pages, 19 figures, 2 tables; updated to published version. Data is available at https://doi.org/10.5281/zenodo.14649137