近日，意大利空间天体物理与宇宙物理研究所的Thomas D. Russell及其研究团队取得一项新进展。经过不懈努力，他们发现中子星上的热核爆炸揭示其喷流速度。相关研究成果已于2024年3月27日在国际权威学术期刊《自然》上发表。

该研究团队报道了每次X射线爆发后，几分钟内喷流发射中出现的明亮耀斑现象，这是由于吸积速率增加所致。借助这些耀斑，研究人员成功测量出中子星紧凑型喷流的速度为v=0.38^+0.11_-0.08c，这比具有相似光度的黑洞喷流速度慢得多。这一重要发现为研究人员提供了一个全新的有力工具，使他们能够深入探究单个系统属性对喷流速度的影响，进而揭示喷流发射的主要机制。

据悉，相对论性喷流在宇宙中广泛存在于吸积和灾难性瞬变过程中，并对周围环境产生深远影响。然而，尽管其重要性不言而喻，喷流的启动机制至今仍是一个未解之谜。对于吸积中子星而言，如果能够测量其紧凑喷流的速度，或许能揭示喷流是由固定在吸积流中的磁场还是恒星本身的磁场所驱动。遗憾的是，至今尚未有有效的测量方法来实现这一目标。此外，这些天体的表面常会出现明亮的爆炸现象，这是由最近吸积物质的不稳定热核燃烧导致的，被称之为I型X射线爆发。在此期间，质量吸积速率会显著增加。

附：英文原文

Title: Thermonuclear explosions on neutron stars reveal the speed of their jets

Author: Russell, Thomas D., Degenaar, Nathalie, van den Eijnden, Jakob, Maccarone, Thomas, Tetarenko, Alexandra J., Snchez-Fernndez, Celia, Miller-Jones, James C. A., Kuulkers, Erik, Del Santo, Melania

Issue&Volume: 2024-03-27

Abstract: Relativistic jets are observed from accreting and cataclysmic transients throughout the Universe, and have a profound impact on their surroundings. Despite their importance, their launch mechanism is not known. For accreting neutron stars, the speed of their compact jets can reveal whether the jets are powered by magnetic fields anchored in the accretion flow or in the star itself, but so far no such measurements exist. These objects can show bright explosions on their surface due to unstable thermonuclear burning of recently accreted material, called type-I X-ray bursts, during which the mass-accretion rate increases. Here, we report on bright flares in the jet emission for a few minutes after each X-ray burst, attributed to the increased accretion rate. With these flares, we measure the speed of a neutron star compact jet to be v=0.38^+0.11_-0.08c, much slower than those from black holes at similar luminosities. This discovery provides a powerful new tool in which we can determine the role that individual system properties have on the jet speed, revealing the dominant jet launching mechanism.

DOI: 10.1038/s41586-024-07133-5

Source: https://www.nature.com/articles/s41586-024-07133-5