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arXiv 1707.04263astro-ph.HE
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中子星合并形成的毫秒磁星中的高能中微子

High-Energy Neutrinos from Millisecond Magnetars formed from the Merger of Binary Neutron Stars

Ke Fang, Brian D. Metzger

摘要:

中子星(NS)双星的合并可能会导致形成一个长寿命的,或无限期稳定的毫秒级磁星遗迹,周围环绕着一个低质量的喷出物壳。磁星巨大的旋转能量的一部分沉积在喷射物后面的脉冲星风星云中,在合并后的几个小时到几天内为发光的光学/X射线发射提供动力。脉冲星风中的离子也可能被加速到超高能量,提供了一个同时发生的高能宇宙射线和中微子源。在早期,宇宙射线经历了强烈的同步辐射损失;然而,大约一天后,通过光介子与星云中的热光子相互作用产生的π介子开始占主导地位,导致高能中微子的有效产生。大约一周后,背景光子的密度下降到足以使宇宙射线逸出光源而不产生二次产物。这些相互竞争的效应导致中微子光变曲线在几天的时间尺度上达到峰值,接近$\sim10^{18}$ eV的能量。这个信号可以通过当前(下一代)中微子望远镜检测到$\sim$ 10(100)Mpc的单个合并,为长期存在的NS残留物提供了明确的证据,否则仅从引力波识别其存在可能具有挑战性。在一个乐观的假设下,即相当大一部分的NS合并产生长寿命的磁星,累积的宇宙学中微子背景估计为$\sim 10^{-9}-10^{-8}\,\rm GeV\,cm^{-2}\,s^{-1}\,sr^{-1}$的NS合并率为$10^{-7}\,\rm Mpc^{-3}\,yr^{-1}$,与冰立方目前的灵敏度重叠,并在下一代中微子望远镜的范围内。

英文摘要:

The merger of a neutron star (NS) binary may result in the formation of a long-lived, or indefinitely stable, millisecond magnetar remnant surrounded by a low-mass ejecta shell. A portion of the magnetar's prodigious rotational energy is deposited behind the ejecta in a pulsar wind nebula, powering luminous optical/X-ray emission for hours to days following the merger. Ions in the pulsar wind may also be accelerated to ultra-high energies, providing a coincident source of high energy cosmic rays and neutrinos. At early times, the cosmic rays experience strong synchrotron losses; however, after a day or so, pion production through photomeson interaction with thermal photons in the nebula comes to dominate, leading to efficient production of high-energy neutrinos. After roughly a week, the density of background photons decreases sufficiently for cosmic rays to escape the source without secondary production. These competing effects result in a neutrino light curve that peaks on a few day timescale near an energy of $\sim10^{18}$ eV. This signal may be detectable for individual mergers out to $\sim$ 10 (100) Mpc by current (next-generation) neutrino telescopes, providing clear evidence for a long-lived NS remnant, the presence of which may otherwise be challenging to identify from the gravitational waves alone. Under the optimistic assumption that a sizable fraction of NS mergers produce long-lived magnetars, the cumulative cosmological neutrino background is estimated to be $\sim 10^{-9}-10^{-8}\,\rm GeV\,cm^{-2}\,s^{-1}\,sr^{-1}$ for a NS merger rate of $10^{-7}\,\rm Mpc^{-3}\,yr^{-1}$, overlapping with IceCube's current sensitivity and within the reach of next-generation neutrino telescopes.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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