Stringent constraint on the radio signal from dark matter annihilation in dwarf spheroidal galaxies using the TGSS

TL;DR

This study uses low-frequency radio observations of dwarf spheroidal galaxies to set stringent limits on dark matter annihilation signals, improving constraints on WIMP properties and demonstrating the effectiveness of a novel image stacking method.

Contribution

The paper introduces a new stacking technique scaled by half-light radius to tighten constraints on dark matter annihilation signals in dwarf galaxies.

Findings

No detectable radio signal from dark matter annihilation was observed.

Constraints on WIMP annihilation cross-section are below the thermal relic level.

The method improves limits over previous analyses and can be applied to future deeper observations.

Abstract

Weakly Interacting Massive Particles (WIMPs) are considered to be one of the favoured dark matter candidates. Searching for any detectable signal due to the annihilation and decay of WIMPs over the entire electromagnetic spectrum has become a matter of interest for the last few decades. WIMP annihilation to Standard Model particles gives rise to a possibility of detection of this signal at low radio frequencies via synchrotron radiation. Dwarf Spheroidal Galaxies (dSphs) are expected to contain a huge amount of dark matter which makes them promising targets to search for such large scale diffuse radio emission. In this work, we present a stacking analysis of 23 dSph galaxies observed at low frequency (147.5MHz) as part of the TIFR-GMRT Sky Survey (TGSS). The non-detection of any signal from these stacking exercises put very tight constraints on the dark matter parameters. The best limit comes from the novel method of stacking after scaling the radio images of the individual dSph galaxy fields after scaling them by the respective half-light radius. The constraint on the thermally averaged cross-section is below the thermal relic cross-section value over a range of WIMP mass for reasonable choices of relevant astrophysical parameters. Such analysis using future deeper observation of individual targets as well as stacking can potentially reveal more about the WIMP dark matter properties.