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