The X-ray Polarization View of Mrk~421 in an Average Flux State as Observed by the Imaging X-ray Polarimetry Explorer
Another exciting result from IXPE! A pretty large polarization from Mrk~421 (factor of three larger than in other bands) was surprisingly detected
This, and lack of polarization variability, basically means that observed X-rays come from shocks near the very engine of the Blazar whereas emission in other bands comes from further away! A solid result showcasing the power of X-ray polarimetry. Congratulations to Laura Di Gesu, the first author of the paper by IXPE collaboration.