The IXPE View of GRB 221009A

Abstract We present the IXPE observation of GRB 221009A, which includes upper limits on linear polarization degree both prompt and afterglow emission in soft X-ray energy band. 221009A is an exceptionally bright gamma-ray burst (GRB) that reached Earth 2022 October 9 after traveling through dust Milky Way. The Imaging Polarimetry Explorer (IXPE) pointed at 11 to observe, for first time, 2–8 keV a afterglow. set limit 13.8% 99% confidence level. This result provides constraints jet opening angle viewing GRB, or alternatively, other properties region. Additionally, captured halo-rings dust-scattered photons are echoes emission. level depends background model assumption, it ranges between ∼55% ∼82%. single pointing assessment study with observations phases.