# The predicted luminous satellite populations around SMC and LMC-mass galaxies - A missing satellite problem around the LMC?

## TL;DR

This study predicts the satellite galaxy populations around LMC-mass galaxies using simulations, addressing the missing satellite problem and implications for galaxy evolution and the Milky Way's satellite system.

## Contribution

It provides new predictions for satellite stellar mass functions around LMC-mass hosts using abundance matching and reionization models, highlighting the discrepancy with observed satellites.

## Key findings

- Predicted 4-8 satellites with stellar mass >10^4 M_sun within 50 kpc of LMC.
- All 12 known satellites have stellar mass between 80 and 3000 M_sun.
- Approximately 53% of satellites were accreted with the LMC and SMC.

## Abstract

Recent discovery of many dwarf satellite galaxies in the direction of the Small and Large Magellanic Clouds (SMC and LMC) provokes questions of their origins, and what they can reveal about galaxy evolution theory. Here, we predict the satellite stellar mass function of Magellanic Cloud-mass host galaxies using abundance matching and reionization models applied to the \textit{Caterpillar} simulations. Specifically focusing on the volume within $50$~kpc of the LMC, we predict a mean of 4-8 satellites with stellar mass $M_* > 10^4\, \mathrm{M_\odot}$, and 3-4 satellites with $80 < M_* \leq 3000\, \mathrm{M_\odot}$. Surprisingly, all $12$ currently known satellite candidates have stellar masses of $80 < M_* \leq 3000\, \mathrm{M_\odot}$. Reconciling the dearth of large satellites and profusion of small satellites is challenging and may require a combination of a major modification of the \mstarmhalo relationship (steep, but with an abrupt flattening at $10^3\, \mathrm{M_\odot}$), late reionization for the Local Group ($z_{\rm{reion}} \lesssim 9$ preferred), and/or strong tidal stripping. We can more robustly predict that $\sim 53\%$ of satellites within this volume were accreted together with the LMC and SMC, and $\sim 47\%$ were only ever Milky Way satellites. Observing satellites of isolated LMC-sized field galaxies is essential to placing the LMC in context, and to better constrain the \mstarmhalo relationship. Modeling known LMC-sized galaxies within $8$ Mpc, we predict 1-6 (2-12) satellites with $M_* > 10^5\, \mathrm{M_\odot}$ ($M_* > 10^4\, \mathrm{M_\odot}$) within the virial volume of each, and 1-3 (1-7) within a single $1.5^{\circ}$ diameter field of view, making their discovery likely.