092090

IXPE has opened a new window to the Universe by measuring X-ray polarizationalready leading to significant progress in our understanding of particleacceleration in blazars. We propose to expand on this success with simultaneousOM/Epic observations of IXPE blazar targets. The proposed XMM-Newton exposuresare needed to determine the spectral shape of the targets thus to obtain robustspectro-polarimetric measurements. The requested data will be part of plannedmultiwavelength campaigns in radio optical and gamma-rays enabling us tobuild simultaneous broaband datasets. Measurement of the mm-to-X-ray continuumspectra of blazars coupled with X-ray polarization will enable us to determinethe mechanism and location of the X-rays as well as test particle acceleration models in blazars. [truncated! Please see actual data for full text]