4 research outputs found
Polarized x-rays from a magnetar
We report on the first detection of linearly polarized x-ray emission from an
ultra-magnetized neutron star with the Imaging X-ray Polarimetry Explorer
(IXPE). The IXPE 35 observations of the anomalous x-ray pulsar 4U 0142+61
reveal a linear polarization degree of throughout the IXPE 2--8
keV band. We detect a substantial variation of the polarization with energy:
the degree is at 2--4 keV and at 5.5--8 keV, while
it drops below the instrumental sensitivity around 4--5 keV, where the
polarization angle swings by . The IXPE observations give us
completely new information about the properties of the neutron star surface and
magnetosphere and lend further support to the presence of the quantum
mechanical effect of vacuum birefringence.Comment: 32 pages, 9 figures, 3 table
The detection of polarized X-ray emission from the magnetar 1E 2259+586
International audienceWe report on IXPE, NICER, and XMM-Newton observations of the magnetar 1E 2259+586. We find that the source is significantly polarized at about or above 20 per cent for all phases except for the secondary peak where it is more weakly polarized. The polarization degree is strongest during the primary minimum which is also the phase where an absorption feature has been identified previously. The polarization angle of the photons are consistent with a rotating vector model with a mode switch between the primary minimum and the rest of the rotation of the neutron star. We propose a scenario in which the emission at the source is weakly polarized (as in a condensed surface) and, as the radiation passes through a plasma arch, resonant cyclotron scattering off of protons produces the observed polarized radiation. This confirms the magnetar nature of the source with a surface field greater than about 1015 G