近日，美国麻省理工学院的Kevin B. Burdge及其研究团队取得一项新进展。经过不懈努力，他们发现黑洞低质量X射线双星V404天鹅座是宽三重星系的一部分。相关研究成果已于2024年10月23日在国际权威学术期刊《自然》上发表。

该研究团队报道了典型黑洞低质量X射线双星（LMXB）V404天鹅座其实是一个宽层次三重星系统的一部分，其中第三个天体距离内部双星系统至少有3500个天文单位（AU）。根据轨道配置，黑洞可能获得了小于5公里每秒的踢力，从而避免了第三个天体的分离。这一发现支持了至少部分黑洞在形成时几乎不产生诞生踢力的观点。此外，该系统中的第三个天体为涉及层级三重星结构的LMXB演化模型提供了支持。

值得注意的是，第三个天体已经演化，表明该系统形成于30至50亿年前，且黑洞已从其演化的次级伴星中吸走了至少半个太阳质量的物质。在黑洞形成的过程中，至少一半的黑洞前体质量坍缩成了黑洞；它甚至可能经历了完全内爆，使得第三个天体得以保持松散束缚。

据悉，有证据表明，当黑洞和中子星等致密天体形成时，它们可能会受到一种“诞生踢力”，在此过程中恒星残骸会获得动量。中子星踢力的观测证据相当丰富，然而关于黑洞诞生踢力的证据却较为有限；此外，一些提出的黑洞形成情景预测其踢力非常小。

附：英文原文

Title: The black hole low-mass X-ray binary V404 Cygni is part of a wide triple

Author: Burdge, Kevin B., El-Badry, Kareem, Kara, Erin, Canizares, Claude, Chakrabarty, Deepto, Frebel, Anna, Millholland, Sarah C., Rappaport, Saul, Simcoe, Rob, Vanderburg, Andrew

Issue&Volume: 2024-10-23

Abstract: Evidence suggests that, when compact objects such as black holes and neutron stars form, they may receive a ‘natal kick’, during which the stellar remnant gains momentum. Observational evidence for neutron star kicks is substantial, yet is limited for black hole natal kicks, and some proposed black hole formation scenarios result in very small kicks. Here we report that the canonical black hole low-mass X-ray binary (LMXB) V404Cygni is part of a wide hierarchical triple with a tertiary companion at least 3,500 astronomical units (AU) away from the inner binary. Given the orbital configuration, the black hole probably received a sub-5kms¹- kick to have avoided unbinding the tertiary. This discovery lends support to the idea that at least some black holes form with nearly no natal kick. Furthermore, the tertiary in this system lends credence to evolutionary models of LMXBs involving a hierarchical triple structure. Remarkably, the tertiary is evolved, indicating that the system formed 3–5billion years ago and that the black hole has removed at least half a solar mass of matter from its evolved secondary companion. During the event in which the black hole formed, it is required that at least half of the mass of the black hole progenitor collapsed into the black hole; it may even have undergone a complete implosion, enabling the tertiary to remain loosely bound.

DOI: 10.1038/s41586-024-08120-6

Source: https://www.nature.com/articles/s41586-024-08120-6