Galaxy Satellites and the Weak Equivalence Principle

TL;DR

This paper uses numerical simulations to explore how a long-range scalar interaction affecting dark matter could explain observed features of Milky Way satellites and stellar streams, challenging previous assumptions about asymmetry.

Contribution

It demonstrates that a strong long-range scalar interaction can produce symmetric stellar streams and satellite properties consistent with observations, offering a new perspective on dark matter interactions.

Findings

Simulations show LRSI can produce symmetric stellar streams like Sagittarius.

Strong LRSI can cause satellites to have high mass-to-light ratios.

LRSI may explain orphan stellar streams and satellite disruption patterns.

Abstract

Numerical simulations of the effect of a long-range scalar interaction (LRSI) acting only on nonbaryonic dark matter, with strength comparable to gravity, show patterns of disruption of satellites that can agree with what is seen in the Milky Way. This includes the symmetric Sagittarius stellar stream. The exception presented here to the Kesden and Kamionkowski demonstration that an LRSI tends to produce distinctly asymmetric streams follows if the LRSI is strong enough to separate the stars from the dark matter before tidal disruption of the stellar component, and if stars dominate the mass in the luminous part of the satellite. It requires that the Sgr galaxy now contains little dark matter, which may be consistent with the Sgr stellar velocity dispersion, for in the simulation the dispersion at pericenter exceeds virial. We present other examples of simulations in which a strong LRSI produces satellites with large mass-to-light ratio, as in Draco, or free streams of stars, which might be compared to "orphan" streams.