The space telescope acquired never seen before details about blazars and about the origin of their emissions.
IXPE is a NASA / ASI mission in which OHB Italia S.p.A., as unique industrial partner, developed fundamental parts of the satellite like the Detector Unit Electronics, the Filter and Calibration Wheel Mechanism and the Detector Service Unit (#DSU) which performs housekeeping activities aboard.
Inside the universe, the energy is produced not only by stars and nebulae but also by free electron jets originating from some of the most powerful cosmic objects: the active galactic nuclei known as ‘blazars’. The ‘flare’ produced by these jets is very bright and, therefore, highly detectable. IXPE (X-ray Polarimetry Explorer) made new incredible detections about the blazar named Markarian 421, an active galactic nucleus and a powerful gamma-ray source located in the constellation Ursa Major, approximately 400 million light years away from the Earth.
Scientists have already known that blazars would be an interesting target for IXPE, but the recent discovery exceeded their best expectations. It has shown how the measurement of X-ray polarization (the capacity to measure the main direction of light waves’ electric field) improves the ability to investigate the complex geometry of the magnetic field and the particles acceleration in different regions of relativistic jets.
Theoretical models, which try to explain the jets’ features, often represent a spiral-helix magnetic field structure, similar to that of the human DNA chain. IXPE however found unexpected changes during three extended observations of Markarian 421 in May and June 2022.
Astronomy community thought that larger rotations would be rare. IXPE revealed instead that the behavior of the polarization angle was not the same during the three observations: in the first one it remained constant, in the second its direction literally made a U-turn, rotating almost 180 degrees in two days. With much surprise, the polarization direction continued to rotate at the same speed in the third observation. This remarkable discovery suggests the idea that the plasma, responsible for the X-ray emission, follows the helical structure of the magnetic field within the jets.
It was really an exciting moment for astrophysical jet studies and an unprecedented insight into the secret of blazers, their geometry and the origin of their emission.