Complementary Test of the Dark Matter Self-Interaction by Direct and Indirect Detections

TL;DR

This paper explores how self-interacting dark matter (SIDM) can be detected through neutrino signals from the Sun, providing a complementary approach to direct detection, especially in regions with small dark matter mass or isospin violation.

Contribution

It demonstrates that neutrino detection from the Sun can probe SIDM parameter spaces inaccessible to direct detection, particularly for small dark matter masses and isospin-violating interactions.

Findings

Neutrino signals can detect SIDM with negligible DM-nucleon cross section.

Detection is effective for very small dark matter masses.

Isospin violation expands the detectable parameter space.

Abstract

The halo dark matter (DM) can be gravitationally captured by the Sun. For self-interacting DM (SIDM), we show that the number of DM trapped inside the Sun remains unsuppressed even if the DM-nucleon cross section is negligible. We consider a SIDM model where $U(1)$ gauge symmetry is introduced to account for the DM self-interaction. Such a model naturally leads to isospin violation for DM-nucleon interaction, although isospin symmetry is still allowed as a special case. We show that the detection of neutrino signature from DM annihilation in the Sun can probe those SIDM parameter ranges not reachable by direct detections. Those parameter ranges are either the region with a very small $m_{\chi}$ or the region opened up due to isospin violations.