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Published December 22, 2022 | Supplemental Material
Journal Article Open

Vela pulsar wind nebula X-rays are polarized to near the synchrotron limit

Xie, Fei ORCID icon
Di Marco, Alessandro ORCID icon
La Monaca, Fabio ORCID icon
Liu, Kuan
Muleri, Fabio ORCID icon
Bucciantini, Niccolò ORCID icon
Romani, Roger W. ORCID icon
Costa, Enrico ORCID icon
Rankin, John ORCID icon
Soffitta, Paolo ORCID icon
Bachetti, Matteo ORCID icon
Di Lalla, Niccolò ORCID icon
Fabiani, Sergio ORCID icon
Ferrazzoli, Riccardo ORCID icon
Gunji, Shuichi ORCID icon
Latronico, Luca ORCID icon
Negro, Michela ORCID icon
Omodei, Nicola ORCID icon
Pilia, Maura ORCID icon
Trois, Alessio ORCID icon
Watanabe, Eri ORCID icon
Agudo, Iván ORCID icon
Antonelli, Lucio A. ORCID icon
Baldini, Luca ORCID icon
Baumgartner, Wayne H. ORCID icon
Bellazzini, Ronaldo ORCID icon
Bianchi, Stefano ORCID icon
Bongiorno, Stephen D. ORCID icon
Bonino, Raffaella ORCID icon
Brez, Alessandro ORCID icon
Capitanio, Fiamma ORCID icon
Castellano, Simone ORCID icon
Cavazzuti, Elisabetta ORCID icon
Ciprini, Stefano ORCID icon
De Rosa, Alessandra ORCID icon
Del Monte, Ettore ORCID icon
Di Gesu, Laura ORCID icon
Donnarumma, Immacolata ORCID icon
Doroshenko, Victor ORCID icon
Dovčiak, Michal ORCID icon
Ehlert, Steven R. ORCID icon
Enoto, Teruaki
Evangelista, Yuri ORCID icon
García, Javier A. ORCID icon
Hayashida, Kiyoshi ORCID icon
Heyl, Jeremy ORCID icon
Iwakiri, Wataru ORCID icon
Jorstad, Svetlana G. ORCID icon
Karas, Vladimir ORCID icon
Kitaguchi, Takao
Kolodziejczak, Jeffery J. ORCID icon
Krawczynski, Henric ORCID icon
Liodakis, Ioannis ORCID icon
Maldera, Simone ORCID icon
Manfreda, Alberto ORCID icon
Marin, Frédéric ORCID icon
Marinucci, Andrea ORCID icon
Marscher, Alan P. ORCID icon
Marshall, Herman L. ORCID icon
Massaro, Francesco ORCID icon
Matt, Giorgio ORCID icon
Mitsuishi, Ikuyuki
Mizuno, Tsunefumi ORCID icon
Ng, C.-Y. ORCID icon
O'Dell, Stephen L. ORCID icon
Oppedisano, Chiara ORCID icon
Papitto, Alessandro ORCID icon
Pavlov, George G. ORCID icon
Peirson, Abel L. ORCID icon
Perri, Matteo ORCID icon
Pesce-Rollins, Melissa ORCID icon
Petrucci, Pierre-Olivier ORCID icon
Possenti, Andrea ORCID icon
Poutanen, Juri ORCID icon
Puccetti, Simonetta ORCID icon
Ramsey, Brian D. ORCID icon
Ratheesh, Ajay ORCID icon
Sgró, Carmelo ORCID icon
Slane, Patrick ORCID icon
Spandre, Gloria ORCID icon
Tamagawa, Toru ORCID icon
Tavecchio, Fabrizio ORCID icon
Taverna, Roberto ORCID icon
Tawara, Yuzuru
Tennant, Allyn F. ORCID icon
Thomas, Nicolas E.
Tombesi, Francesco ORCID icon
Tsygankov, Sergey S. ORCID icon
Turolla, Roberto ORCID icon
Vink, Jacco ORCID icon
Weisskopf, Martin C. ORCID icon
Wu, Kinwah ORCID icon
Zane, Silvia ORCID icon


Pulsar wind nebulae are formed when outflows of relativistic electrons and positrons hit the surrounding supernova remnant or interstellar medium at a shock front. The Vela pulsar wind nebula is powered by a young pulsar (B0833-45, aged 11,000 years) and located inside an extended structure called Vela X, which is itself inside the supernova remnant. Previous X-ray observations revealed two prominent arcs that are bisected by a jet and counter jet. Radio maps have shown high linear polarization of 60% in the outer regions of the nebula. Here we report an X-ray observation of the inner part of the nebula, where polarization can exceed 60% at the leading edge—approaching the theoretical limit of what can be produced by synchrotron emission. We infer that, in contrast with the case of the supernova remnant, the electrons in the pulsar wind nebula are accelerated with little or no turbulence in a highly uniform magnetic field.

Additional Information

© The Author(s), under exclusive licence to Springer Nature Limited 2022. The IXPE is a joint US and Italian mission. The US contribution is supported by the National Aeronautics and Space Administration (NASA) and is led and managed by the 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-2017-12-I.0, agreements ASI-INAF-2017-12-H0 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) that are distributed with additional software tools by the High-Energy Astrophysics Science Archive Research Center (HEASARC), at NASA Goddard Space Flight Center (GSFC). The research at Guangxi University was supported in part by National Natural Science Foundation of China (grant no. 12133003). The research at Boston University was supported in part by National Science Foundation grant AST-2108622. I.A. acknowledges financial support from the Spanish 'Ministerio de Ciencia e Innovación' (MCINN) through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709) and through grants AYA2016-80889-P and PID2019-107847RB-C44. Contributions. F.X. led the data analysis and the writing of the paper. A.D.M. and F.L.M. performed the spectropolarimetric analysis and contributed to the paper. F. Muleri and J.R. contributed to the data analysis and energy calibration of the dataset. K.L. and N.B. contributed to the data analysis and result interpretation. R.W.R. and L.L. helped to revise the manuscript. E. Costa, P. Soffitta, M.B., S.F., R.F., M. Pilia and A.T. contributed to the interpretation of the results and to text revisions. N.D.L., S.G., N.O., M.N. and E.W. performed independent analysis of the data. The other authors contributed to the design of the mission, to the calibration of the instrument, to the definition of its scientific case and to the planning of the observations. All of the authors provided inputs and comments on the manuscript. Data availability. IXPE data are available through the NASA's HEASARC data archive (https://heasarc.gsfc.nasa.gov). Other derived data supporting the findings of this study are available from the corresponding author on request. Source data are provided with this paper. Code availability. The High Energy Astrophysics Science Archive Research Center (HEASARC) developed the HEASOFT (HEASARC Software). We used the HEASOFT v.6.30.1 package for the spectropolarimetric IXPE data analysis, which is available online (https://heasarc.gsfc.nasa.gov/docs/software/heasoft/). The proper instrument response functions are provided by the IXPE Team as a part of the IXPE calibration database released on 14 March 2022 are and available in the HEASARC Calibration Database (https://heasarc.gsfc.nasa.gov/docs/heasarc/caldb/caldb_supported_missions.html). The software developed by IXPE collaboration is available publicly online (https://ixpeobssim.readthedocs.io/en/latest/?badge=latest). Information supporting the findings of this study is available from the corresponding author on request. The authors declare no competing interests.

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Additional details

August 22, 2023
October 25, 2023