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X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho’s supernova remnant

Ferrazzoli, R; Slane, P; Prokhorov, D; Zhou, P; Vink, J; ..; Turolla, R; ... Zane, S; + view all (2023) X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho’s supernova remnant. The Astrophysical Journal (In press). Green open access

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Abstract

Supernova remnants are commonly considered to produce most of the Galactic cosmicrays via diffusive shock acceleration. However, many questions about the physical conditions at shock fronts, such as the magnetic-field morphology close to the particle acceleration sites, remain open. Here we report the detection of a localized polarization signal from some synchrotron X-ray emitting regions of Tycho’s supernova remnant made by the Imaging X-ray Polarimetry Explorer. The derived polarization degree of the X-ray synchrotron emission is 9±2% averaged over the whole remnant, and 12±2% at the rim, higher than the 7–8% polarization value observed in the radio band. In the west region the polarization degree is 23 ± 4%. The X-ray polarization degree in Tycho is higher than for Cassiopeia A, suggesting a more ordered magnetic-field or a larger maximum turbulence scale. The measured tangential polarization direction corresponds to a radial magnetic field, and is consistent with that observed in the radio band. These results are compatible with the expectation of turbulence produced by an anisotropic cascade of a radial magnetic-field near the shock, where we derive a magnetic-field amplification factor of 3.4 ± 0.3. The fact that this value is significantly smaller than those expected from acceleration models is indicative of highly anisotropic magneticfield turbulence, or that the emitting electrons either favor regions of lower turbulence, or accumulate close to where the magnetic-field orientation is preferentially radially oriented due to hydrodynamical instabilities.

Type: Article
Title: X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho’s supernova remnant
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10163381
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