Soft X‐ray polarization in thermal magnetar emission
Soft X‐ray polarization in thermal magnetar emission
复制标题
热磁发射中的软 X 射线偏振
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
R. Perna
中科院分区：
文献类型：
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作者：
M. Adelsberg;R. Perna
软 X 射线带中磁星的发射光谱可能包含直接从中子星 (NS) 表面产生的热成分。然而，静态光谱中缺乏观察到的类似吸收的特征，使得直接限制大气的物理特性变得困难。我们认为，未来的 X 射线偏振测量代表了一种直接约束磁星磁场强度和几何形状的有前途的技术。我们使用磁场 B = 4 x 10 13 ―5 × 10 14 G 的最新 NS 大气模型构建了从有限表面热点观测到的偏振信号的模型。我们的计算强烈依赖于 NS 磁场强度和几何形状，而更弱地依赖于 NS 状态方程和大气成分。我们讨论了相位分辨光谱和偏振测量的互补依赖性如何解决目前阻碍使用热模型确定磁星物理参数的简并性。
Emission spectra from magnetars in the soft X-ray band likely contain a thermal component emerging directly from the neutron star (NS) surface. However, the lack of observed absorption-like features in quiescent spectra makes it difficult to directly constrain physical properties of the atmosphere. We argue that future X-ray polarization measurements represent a promising technique for directly constraining the magnetar magnetic field strength and geometry. We construct models of the observed polarization signal from a finite surface hotspot, using the latest NS atmosphere models for magnetic fields B = 4 x 10 13 ―5 × 10 14 G. Our calculations are strongly dependent on the NS magnetic field strength and geometry, and are more weakly dependent on the NS equation of state and atmosphere composition. We discuss how the complementary dependencies of phase-resolved spectroscopy and polarimetry might resolve degeneracies that currently hamper the determination of magnetar physical parameters using thermal models.