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arXiv 1802.04690astro-ph.HE
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星系晕脉冲星群

The Galactic halo pulsar population

Kaustubh Rajwade, Jayanth Chennamangalam, Duncan Lorimer, Aris Karastergiou

摘要:

到目前为止,大多数对恒星的研究都集中在银河系的圆盘、银河系中心、球状星团和附近的星系上。由于出生时的撞击,我们可以预期在星系晕中也会发现恒星。我们调查可能的人口的规范(即非回收)的无线电的光环,估计这样的卫星的数量,以及通过单脉冲和周期性搜索可检测到的分数。此外,我们探讨了这个人口的通量密度和分散措施的分布。我们还考虑了不同的速度模型以及倾角和磁场的演化对结果的影响。我们发现,所有向地球辐射的恒星中有$\sim$ 33%在晕中,但如果我们让倾角和磁场按下降指数演化,则该比例减少到$\sim$ 1.5%。此外,可检测的部分受到调查灵敏度的显著限制。使用时域周期性搜索算法的调查将最有效地探测这一人群。如果我们假设磁晕中磁晕星的倾角和磁场随时间演化,就可以解释目前磁晕中磁晕星的探测不到。我们还强调了一个可能的混淆明亮的脉冲从晕星和快速射电暴与低色散措施,进一步的后续行动是必要的。

英文摘要:

Most population studies of pulsars have hitherto focused on the disc of the Galaxy, the Galactic centre, globular clusters, and nearby galaxies. It is expected that pulsars, by virtue of their natal kicks, are also to be found in the Galactic halo. We investigate the possible population of canonical (i.e. non-recycled) radio pulsars in the halo, estimating the number of such pulsars, and the fraction that is detectable via single pulse and periodicity searches. Additionally, we explore the distributions of flux densities and dispersion measures of this population. We also consider the effects of different velocity models and the evolution of inclination angle and magnetic field on our results. We show that $\sim$33 % of all pulsars beaming towards the Earth are in the halo but the fraction reduces to $\sim$1.5 % if we let the inclination angle and the magnetic field evolve as a falling exponential. Moreover, the fraction that is detectable is significantly limited by the sensitivity of surveys. This population would be most effectively probed by surveys using time-domain periodicity search algorithms. The current non-detections of pulsars in the halo can be explained if we assume that the inclination angle and magnetic field of pulsars evolve with time. We also highlight a possible confusion between bright pulses from halo pulsars and Fast Radio Bursts with low dispersion measures where further follow-up is warranted.

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