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arXiv 1602.05993astro-ph.HE
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类船帆座脉冲星B1800-21频谱的时变

Time variation in the low frequency spectrum of Vela-like pulsar B1800-21

Rahul Basu, Karolina Rożko, Wojciech Lewandowski, Jarosław Kijak, Marta Dembska

摘要:

本文报道了类船帆座脉冲星B1800-21在低射频区几年多历元的流量测量结果。该频谱显示出在GHz频率范围附近的翻转,代表了千兆赫兹峰值频谱(GPS)脉冲星的典型例子。我们的观测结果表明,脉冲星光谱在观测期间显示出显着的演变,频谱的低频部分变得更陡,具有更高的周转频率,在最近的测量期间恢复到初始形状之前的几年时间。光谱变化时间跨越几年需要密集的结构,自由电子密度约1000- 20000厘米$^{-3}$和物理尺寸~220 AU,在星际介质(ISM)穿越脉冲星视线。我们期待在ISM和可能的机制,特别是热自由吸收的这种结构的可能的网站作为可能的解释的变化。

英文摘要:

We report the flux measurement of the Vela like pulsar B1800-21 at the low radio frequency regime over multiple epochs spanning several years. The spectrum shows a turnover around the GHz frequency range and represents a typical example of gigahertz-peaked spectrum (GPS) pulsar. Our observations revealed that the pulsar spectrum show a significant evolution during the observing period with the low frequency part of the spectrum becoming steeper, with a higher turnover frequency, for a period of several years before reverting back to the initial shape during the latest measurements. The spectral change over times spanning several years requires dense structures, with free electron densities around 1000--20000 cm$^{-3}$ and physical dimensions ~220 AU, in the interstellar medium (ISM) traversing across the pulsar line of sight. We look into the possible sites of such structures in the ISM and likely mechanisms particularly the thermal free-free absorption as possible explanations for the change.

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