On the spectrum and polarization of magnetar flare emission
Abstract
Bursts and flares are among the distinctive observational manifestations of magnetars, isolated neutron stars endowed with an ultra-strong magnetic field (B ≈ 1014-1015 G). It is believed that these events arise in a hot electron-positron plasma, injected in the magnetosphere, due to a magnetic field instability, which remains trapped within the closed magnetic field lines (the “trapped-fireball” model). We have developed a simple radiative transfer model to simulate magnetar flare emission in the case of a steady trapped fireball. We assume that magnetic Thomson scattering is the dominant source of opacity in the fireball medium, and neglect contributions from second-order radiative processes. The spectra we obtained in the 1-100 keV energy range are in broad agreement with those of available observations. The large degree of polarization (≳ 80%) predicted by our model should be easily measured by new-generation X-ray polarimeters, like IXPE, XIPE and eXTP, allowing one to confirm the model predictions.
- Publication:
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Journal of Physics Conference Series
- Pub Date:
- December 2017
- DOI:
- 10.1088/1742-6596/932/1/012023
- Bibcode:
- 2017JPhCS.932a2023T