Presentation #101A.04 in the session GRB 221009a.
GRB 221009A is an exceptionally bright gamma-ray burst that reached Earth on October 9th 2022. A fraction of the soft X-rays of the bright prompt emission were scattered by Galactic dust clouds along the line of sight and produced halo rings echoing for a few days after the initial trigger. The Imaging X-ray polarimetry Explorer (IXPE) pointed at GRB 221009A on October 11th to observe, for the first time, the 2-8 keV X-ray polarization of a GRB afterglow. Exceeding the primary goal, IXPE also captured the echoes of the GRB prompt emission detecting two halo-rings of scattered photons. In this presentation we report the results of the IXPE observation of GRB 221009A.
A special thank goes to the IXPE Collaboration and Operation Team, and in particular to the working group that supported both data analysis and interpretation.