# Too Big To Fail in Light of Gaia

## TL;DR

This paper reveals an anti-correlation between dark matter density and orbital proximity in Milky Way dwarf galaxies, suggesting new insights into the too-big-to-fail problem and galaxy formation.

## Contribution

It identifies a correlation between dark matter density and orbital history of dwarf galaxies, challenging previous assumptions and prompting a reevaluation of the too-big-to-fail issue.

## Key findings

- Less dense dark matter in distant dSphs like Fornax and Carina.
- Closer dSphs like Draco have higher dark matter densities.
- Extended stellar distributions correlate with lower dark matter densities.

## Abstract

We point out an anti-correlation between the central dark matter (DM) densities of the bright Milky Way dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances inferred from Gaia data. The dSphs that have not come close to the Milky Way center (like Fornax, Carina and Sextans) are less dense in DM than those that have come closer (like Draco and Ursa Minor). The same anti-correlation cannot be inferred for the ultra-faint dSphs due to large scatter. Including ultra-faints, a trend that dSphs with more extended stellar distributions tend to have lower DM densities emerges. A fresh look at solutions to the too-big-to-fail problem is warranted in light of these observations.