02.06.2023 / 10:10 / Zeuthen, Hybridmeeting in Villa | SR5

The expansion and polarization of the nonthermal X-ray filaments in Cassiopeia A

Jacco Vink | University of Amsterdam

About the speaker: Jacco Vink is Associate Professor at the University of Amsterdam. After obtaining his PhD at University Utrecht in 1999, he worked at the Institute Potsdam and was NASA Chandra fellow at Columbia University in New York. In 2005, after a brief position at SRON Utrecht, he became a faculty member at Utrecht University. In 2012 he was hired as a member of the UvA GRAPPA excellence center for astroparticle physics. He is an NWO Vidi grant recipient and was a member of the ESA Astronomical Working Group. He is a member of the H.E.S.S. collaboration, and NASA IXPE’s science team. Abstract: Cassiopeia A is the youngest core-collapse supernova remnant in the Galaxy, and one of the best studied supernova remnants overall. Imaging X-ray spectroscopy have a high information content, and show a clumpy structure of supernova ejecta, rich in oxygen, silicon and iron, with an uneven distribution across the remnant. The 4-6 keV band, however, is dominated by nonthermal X-ray emission, and the morphology shows thin (arcsecond-sized) filaments in two main regions: one associated with the supernova blast wave, and one with the reverse shock. In this talk I will detailed both the dynamics of the forward and reverse shock as measured using 20 years of observations with the Chandra X-ray Observatory, as well as measurements of the X-ray polarization with the recently launched Imaging X-ray Polarimetry Explorer (IXPE). The latter shows that the polarization degree is low. I will discuss how this could either be due to a high level of turbulence, or perhaps provides an hint for a "jitter radiation” component, jitter radiation being an extension of the synchrotron model, but in the presence of high turbulence at small physical scales.

More Information: https://confluence.desy.de/display/DESYAstroparticlePublic/Astroparticle+Seminar