PSR J0738-4042的自旋下降率降低，解释为小行星破坏事件所致
Reduced spin-down rate of PSR J0738-4042 explained as due to an asteroid disruption event
摘要：
Brook等人的长期观察表明PSR J 0738 -4042的旋转频率导数在2005年突然变化。最初，自旋下降速率相对稳定，旋转频率导数为$-1.14 \times 10^{-14}~\rm s^{-2}$。2005年9月以后，衍生品开始上涨。大约1000天后，它达到了另一个相对稳定的值，大约为$-0.98 \times 10^{-14}~\rm s^{-2}$，表明脉冲星的自转速度相对较慢。为了解释观测到的自旋下降速率变化，我们求助于一颗被PSR J 0738 -4042破坏的小行星。在我们的模型中，假设小行星的轨道角动量平行于旋转脉冲星的轨道角动量，因此，自旋下降速率的显著降低可以自然地解释为由于角动量从被破坏的物质转移到中心脉冲星。磁层半径约为$4.0 \times 10^{9}$ cm，小于潮汐破裂半径（$4.9 \times 10^{10}$ cm）。我们的模型是自洽的。结果表明，PSR J 0738 -4042的自旋下降率的变化可以定量地解释由中央脉冲星中断的小行星吸积。
英文摘要：
Long term observations by Brook et al. reveal that the derivative of rotational frequency of PSR J0738-4042 changed abruptly in 2005. Originally, the spin-down rate was relatively stable, with the rotational frequency derivative of $-1.14 \times 10^{-14}~\rm s^{-2}$. After September 2005, the derivative began to rise up. About 1000 days later, it arrived at another relatively stable value of about $-0.98 \times 10^{-14}~\rm s^{-2}$, indicating that the pulsar is spinning-down relatively slowly. To explain the observed spin-down rate change, we resort to an asteroid disrupted by PSR J0738-4042. In our model, the orbital angular momentum of the asteroid is assumed to be parallel to that of the rotating pulsar, so that the pronounced reduction in the spin-down rate can be naturally explained as due to the transfer of the angular momentum from the disrupted material to the central pulsar. The derived magnetospheric radius is about $4.0 \times 10^{9}$ cm, which is smaller than the tidal disruption radius ($4.9 \times 10^{10}$ cm). Our model is self-consistent. It is shown that the variability of the spin-down rate of PSR J0738-4042 can be quantitatively accounted for by the accretion from the asteroid disrupted by the central pulsar.
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