TY - JOUR
T1 - Shedding new light on the Crab with polarized X-rays
AU - Chauvin, M.
AU - Florén, H. G.
AU - Friis, M.
AU - Jackson, M.
AU - Kamae, T.
AU - Kataoka, J.
AU - Kawano, T.
AU - Kiss, M.
AU - Mikhalev, V.
AU - Mizuno, T.
AU - Ohashi, N.
AU - Stana, T.
AU - Tajima, H.
AU - Takahashi, H.
AU - Uchida, N.
AU - Pearce, M.
N1 - Funding Information:
This research was supported in Sweden by The Swedish National Space Board, The Knut and Alice Wallenberg Foundation, and The Swedish Research Council. In Japan, support was provided by Japan Society for Promotion of Science and ISAS/JAXA. SSC are thanked for providing expert mission support and launch services at Esrange Space Centre. DST Control developed the PoGO+ attitude control system under the leadership of J.-E. Strömberg. Contributions from past Collaboration members and students are acknowledged. In particular, we thank M. Kole, E. Moretti, G. Olofsson and S. Rydström for their important contributions to the PoGOLite Pathfinder mission from which PoGO+ was developed.
Publisher Copyright:
© 2017 The Author(s).
PY - 2017/12/1
Y1 - 2017/12/1
N2 - Strong magnetic fields, synchrotron emission, and Compton scattering are omnipresent in compact celestial X-ray sources. Emissions in the X-ray energy band are consequently expected to be linearly polarized. X-ray polarimetry provides a unique diagnostic to study the location and fundamental mechanisms behind emission processes. The polarization of emissions from a bright celestial X-ray source, the Crab, is reported here for the first time in the hard X-ray band (~20-160 keV). The Crab is a complex system consisting of a central pulsar, a diffuse pulsar wind nebula, as well as structures in the inner nebula including a jet and torus. Measurements are made by a purpose-built and calibrated polarimeter, PoGO+. The polarization vector is found to be aligned with the spin axis of the pulsar for a polarization fraction, PF = (20.9 ± 5.0)%. This is higher than that of the optical diffuse nebula, implying a more compact emission site, though not as compact as, e.g., the synchrotron knot. Contrary to measurements at higher energies, no significant temporal evolution of phase-integrated polarisation parameters is observed. The polarization parameters for the pulsar itself are measured for the first time in the X-ray energy band and are consistent with observations at optical wavelengths.
AB - Strong magnetic fields, synchrotron emission, and Compton scattering are omnipresent in compact celestial X-ray sources. Emissions in the X-ray energy band are consequently expected to be linearly polarized. X-ray polarimetry provides a unique diagnostic to study the location and fundamental mechanisms behind emission processes. The polarization of emissions from a bright celestial X-ray source, the Crab, is reported here for the first time in the hard X-ray band (~20-160 keV). The Crab is a complex system consisting of a central pulsar, a diffuse pulsar wind nebula, as well as structures in the inner nebula including a jet and torus. Measurements are made by a purpose-built and calibrated polarimeter, PoGO+. The polarization vector is found to be aligned with the spin axis of the pulsar for a polarization fraction, PF = (20.9 ± 5.0)%. This is higher than that of the optical diffuse nebula, implying a more compact emission site, though not as compact as, e.g., the synchrotron knot. Contrary to measurements at higher energies, no significant temporal evolution of phase-integrated polarisation parameters is observed. The polarization parameters for the pulsar itself are measured for the first time in the X-ray energy band and are consistent with observations at optical wavelengths.
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U2 - 10.1038/s41598-017-07390-7
DO - 10.1038/s41598-017-07390-7
M3 - Article
C2 - 28798398
AN - SCOPUS:85043356252
VL - 7
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 7816
ER -