Multiwavelength Polarization of Rotation-powered Pulsars

作者：Harding Alice K; Kalapotharakos Constantinos

来源：Astrophysical Journal, 2017, 840(2): 73.

DOI：10.3847/1538-4357/aa6ead

<jats:title>Abstract</jats:title>
<jats:p>Polarization measurements provide strong constraints on models for emission from rotation-powered pulsars. We present multiwavelength polarization predictions showing that measurements over a range of frequencies can be particularly important for constraining the emission location, radiation mechanisms, and system geometry. The results assume a generic model for emission from the outer magnetosphere and current sheet in which optical to hard X-ray emission is produced by synchrotron radiation (SR) from electron–positron pairs and <jats:italic>γ</jats:italic>-ray emission is produced by curvature radiation (CR) or SR from accelerating primary electrons. The magnetic field structure of a force-free magnetosphere is assumed and the phase-resolved and phase-averaged polarization is calculated in the frame of an inertial observer. We find that large position angle (PA) swings and deep depolarization dips occur during the light-curve peaks in all energy bands. For synchrotron emission, the polarization characteristics are strongly dependent on photon emission radius with larger, nearly 180°, PA swings for emission outside the light cylinder (LC) as the line of sight crosses the current sheet. The phase-averaged polarization degree for SR is less that 10% and around 20% for emission starting inside and outside the LC, respectively, while the polarization degree for CR is much larger, up to 40%–60%. Observing a sharp increase in polarization degree and a change in PA at the transition between X-ray and <jats:italic>γ</jats:italic>-ray spectral components would indicate that CR is the <jats:italic>γ</jats:italic>-ray emission mechanism.</jats:p>

• 出版日期2017-5-10