The Imaging X-ray Polarimetry Explorer (IXPE) observed for the first timehighly polarized X-ray emission from the magnetar 1E 1841-045, targeted after aburst-active phase in August 2024. To date, IXPE has observed four othermagnetars during quiescent periods, highlighting substantially differentpolarization properties. 1E 1841-045 exhibits a high, energy-dependentpolarization degree, which increases monotonically from ~15% at 2-3 keV up to~55% at 5.5-8 keV, while the polarization angle, aligned with the celestialNorth, remains fairly constant. The broadband spectrum (2-79 keV) obtained bycombining simultaneous IXPE and NuSTAR data is well modeled by a blackbody andtwo power-law components. The unabsorbed 2-8 keV flux (~2E-11 erg/cm2/s) isabout 10% higher than that obtained from archival XMM-Newton and NuSTARobservations. The polarization of the soft, thermal component does not exceed~25%, and may be produced by a condensed surface or a bombarded atmosphere. Theintermediate power law is polarized at around 30%, consistent with predictionsfor resonant Compton scattering in the star magnetosphere; while, the hardpower law exhibits a polarization degree exceeding 65%, pointing to asynchrotron/curvature origin.
IXPE detection of highly polarized X-rays from the magnetar 1E 1841-045
Paolo Esposito;
In corso di stampa
Abstract
The Imaging X-ray Polarimetry Explorer (IXPE) observed for the first timehighly polarized X-ray emission from the magnetar 1E 1841-045, targeted after aburst-active phase in August 2024. To date, IXPE has observed four othermagnetars during quiescent periods, highlighting substantially differentpolarization properties. 1E 1841-045 exhibits a high, energy-dependentpolarization degree, which increases monotonically from ~15% at 2-3 keV up to~55% at 5.5-8 keV, while the polarization angle, aligned with the celestialNorth, remains fairly constant. The broadband spectrum (2-79 keV) obtained bycombining simultaneous IXPE and NuSTAR data is well modeled by a blackbody andtwo power-law components. The unabsorbed 2-8 keV flux (~2E-11 erg/cm2/s) isabout 10% higher than that obtained from archival XMM-Newton and NuSTARobservations. The polarization of the soft, thermal component does not exceed~25%, and may be produced by a condensed surface or a bombarded atmosphere. Theintermediate power law is polarized at around 30%, consistent with predictionsfor resonant Compton scattering in the star magnetosphere; while, the hardpower law exhibits a polarization degree exceeding 65%, pointing to asynchrotron/curvature origin.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
