A1 Refereed original research article in a scientific journal
Analysis of Crab X-Ray Polarization Using Deeper Imaging X-Ray Polarimetry Explorer Observations
Authors: Wong, J.; Mizuno, T.; Bucciantini, N.; Romani, R.W.; Yang, Y.J.; Liu, K.; Deng, W.; Goya, K.; Xie, F.; Pilia, M.; Kaaret, P.; Weisskopf, M.C.; Silvestri, S.; Ng, C.Y.; Chen, C.T.; Agudo, I.; Antonelli, L.A.; Bachetti, M.; Baldini, L.; Baumgartner, W.H.; Bellazzini, R.; Bianchi, S.; Bongiorno, S.D.; Bonino, R.; Brez, A.; Capitanio, F.; Castellano, S.; Cavazzuti, E.; Ciprini, S.; Costa, E.; De Rosa, A.; Del Monte, E.; Di Gesu, L.; Di Lalla, N.; Di Marco, A.; Donnarumma, I.; Doroshenko, V.; Dovčiak, M.; Ehlert, S.R.; Enoto, T.; Evangelista, Y.; Fabiani, S.; Ferrazzoli, R.; Garcia, J.A.; Gunji, S.; Heyl, J.; Iwakiri, W.; Jorstad, S.G.; Karas, V.; Kislat, F.; Kitaguchi, T.; Kolodziejczak, J.J.; Krawczynski, H.; La Monaca, F.; Latronico, L.; Liodakis, I.; Maldera, S.; Manfreda, A.; Marin, F.; Marinucci, A.; Marscher, A.P.; Marshall, H.L.; Massaro, F.; Matt, G.; Mitsuishi, I.; Muleri, F.; Negro, M.; O’Dell, S.L.; Omodei, N.; Oppedisano, C.; Papitto, A.; Pavlov, G.G.; Peirson, A.L.; Perri, M.; Pesce-Rollins, M.; Petrucci, P.O.; Possenti, A.; Poutanen, J.; Puccetti, S.; Ramsey, B.D.; Rankin, J.; Ratheesh, A.; Roberts, O.J.; Sgró, C.; Slane, P.; Soffitta, P.; Spandre, G.; Swartz, D.A.; Tamagawa, T.; Tavecchio, F.; Taverna, R.; Tawara, Y.; Tennant, A.F.; Thomas, N.E.; Tombesi, F.; Trois, A.; Tsygankov, S.; Turolla, R.; Vink, J.; Wu, K.; Zane, S.
Publisher: Institute of Physics
Publication year: 2024
Journal: Astrophysical Journal
Journal name in source: Astrophysical Journal
Article number: 172
Volume: 973
Issue: 2
ISSN: 0004-637X
eISSN: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ad6309
Web address : https://doi.org/10.3847/1538-4357/ad6309
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/458474675
We present Crab X-ray polarization measurements using Imaging X-Ray Polarimetry Explorer (IXPE) data with a total exposure of 300 ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped +40° polarization angle sweep in the main pulse and >1σ departures from the OPTIMA optical polarization in both pulses, suggesting different radiation mechanisms or sites for the polarized emission at the two wavebands. Our polarization map of the inner nebula reveals a toroidal magnetic field, as seen in prior IXPE analyses. Along the southern jet, the magnetic field orientation relative to the jet axis changes from perpendicular to parallel and the polarization degree decreases by ∼6%. These observations may be explained by kink instabilities along the jet or a collision with a dense, jet-deflecting medium at the tip. Using spectropolarimetric analysis, we find asymmetric polarization in the four quadrants of the inner nebula, as expected for a toroidal field geometry, and a spatial correlation between polarization degree and photon index.
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Funding information in the publication:
This work was supported in part through NASA grant NNM17AA26C administered by the Marshall Space Flight Center. The Imaging X-ray Polarimetry Explorer (IXPE) is a joint US and Italian mission. The US contribution is supported by the National Aeronautics and Space Administration (NASA) and led and managed by its Marshall Space Flight Center (MSFC), with industry partner Ball Aerospace (contract NNM15AA18C). The Italian contribution is supported by the Italian Space Agency (Agenzia Spaziale Italiana, ASI) through contract ASI-OHBI-2022-13-I.0, agreements ASI-INAF-2022-19-HH.0 and ASI-INFN-2017.13-H0, and its Space Science Data Center (SSDC) with agreements ASI-INAF-2022-14-HH.0 and ASI-INFN 2021-43-HH.0, and by the Istituto Nazionale di Astrofisica (INAF) and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. This research used data products provided by the IXPE Team (MSFC, SSDC, INAF, and INFN) and distributed with additional software tools by the High-Energy Astrophysics Science Archive Research Center (HEASARC), at the NASA Goddard Space Flight Center (GSFC). N.B. was supported by the INAF MiniGrant "PWNnumpol—Numerical Studies of Pulsar Wind Nebulae in The Light of IXPE." F.X. is supported by the National Natural Science Foundation of China (grant No. 12373041). T. M. was supported by JSPS KAKENHI grant No. 23K25882. I.L. was supported by the NASA Postdoctoral Program at the Marshall Space Flight Center, administered by Oak Ridge Associated Universities under contract with NASA. This paper employs the Chandra data set, obtained by the Chandra X-ray Observatory, contained in doi:10.25574/cdc.264.
