Silvia tells us about her recent use of Planck satellite data to search for dark matter. She doesn’t use the CMB though, instead she is looking for microwave emission from the galactic centre. For her, the CMB is noise!

If dark matter decay/annihilation leads to electron positron emission then those electrons and positrons would emit microwave light through synchrotron radiation as they travel through the magnetic fields at the galactic centre.

She found that the polarisation signal is a more sensitive probe of this effect than the intensity. The main theory for why this is is that the observed signal in the polarisation has more features (coherent hot and cold spots), whereas the expected dark matter signal should be more smooth. Whereas both the intensity measurement and signal should be more smooth. Therefore, the observed polarisation “cold spots” can best constrain the dark matter signal, especially close to the galactic centre, where the dark matter signal should still be strong.

Silvia: https://silviamanconi.wordpress.com/
Paper: https://arxiv.org/abs/2204.04232