An international team has found a neutron star that captures material from a companion star through a violent and unstable process.
This mechanism, previously only observed in superluminous black holes, shows that the so-called “accretion instability” is in fact a fundamental physical process. Moreover, this discovery opens up a new general scenario explaining the intense accumulation of matter on compact objects. The study has been published in the journal Nature.
X-ray binaries They are systems composed of a compressed body, neutron star or Black hole And a star similar in size to the sun. The compact object absorbs material from the companion star through a disk that emits large amounts of light, especially in X-rays. This process by which the compressed object attracts matter is known as matter backlog, usually occurs in the form of violent volcanic eruptions during which the system becomes a thousand times brighter. In addition, some of the removed material that rotates toward the compact body in the disk is pushed back into space by winds or Article streams.
The X-ray binary known as Swift J1858.6-0814 was discovered in 2018 during one of these spectacular volcanic episodes, confusing the astronomical community from early observations. The system showed incredible year-long glows, emitting in all wavelengths, from radio to X-rays. The origin of these “cosmic fireworks” was unknown, but they were so bright that the scientific community concluded that the compact object must be a black hole. However, the discovery of fusion explosions in 2020 showed the presence of a solid surface on the compact object, confirming that Swift J1858.6-0814 contains a neutron star.
Through a multi-telescope observation campaign, the team found that Swift J1858.6-0814 exhibits the same strange accretion instability as GRS 1915+105, the black hole that served as a Rosetta stone for deciphering the complex behavior of this neutron star. These instabilities occur at very high brightness, resulting in oscillations of large amplitude in the accretion disk and strong extrusion of matter. explains Federico Vincentelli, IAC researcher and first author condition. This dramatic process is still poorly understood and has so far only been observed in detail in a system where the compact object is a black hole. he adds.
By comparing the two systems, the research team was able to investigate aspects not seen before. We realized that we could explain the complex phenomenon of both objects with three components: an unstable accretion disk, which produces highly variable X-ray emission as the interiors of the disk periodically empty and fill; frequent extrusion of matter (formed after emptying the disc), which can be observed in radio and infrared waves; And bright echoes of these internal changes are in the outer regions of the disk, which can be observed from infrared to ultraviolet Vincentelli said.
This study shows that such “instability” is a fundamental physical process and is independent of the nature of the compressed object. This paper presents a new scenario that allows us to explain what happens near these exotic objects (neutron stars and black holes) when material is accreted at very high speeds. — points out Montserrat Armas Padilla, researcher at IAC and co-author of the article.
This result was achieved through an intense, simultaneous multi-wavelength observational campaign using five space and ground-based telescopes.
Looking to future research, this latest finding provides the scientific community with new ingredients for understanding the origin of cumulative instability. We now plan to extend this type of research to other hyperluminous systems to shed light on black holes and neutron stars as they gather matter at extreme speeds. Vincentelli concludes.
Pictured: Artist’s impression of the fiery explosion of the neutron star Swift J1858.6-0814 compared to the black hole GRS 1915+105. Credit: Gabriel Pérez Diaz (IAC)
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