There is a beginning for everything. Even black holes.
Last week we spoke of a new discovery ‘silent’ black hole inside a globular cluster called NGC 1850, which is located in a nearby galaxy. The cosmic throat is approximately 11 times the mass of the Sun and is trapped in a binary system in orbit with another star. But while it doesn’t show the extent of typical black hole predation on its poor cosmic companion star, it will eat it up alive in the end as the death dance continues until nothing is left but a stripped core that slowly fades into a white dwarf, so the study initially together with a preprint server.
And investigating young black holes like this one could go further than uncovering the early development of black holes: it could also vastly improve our ability to spot black holes at various stages in their first steps, both feeding and “sleeping” to enhance.
A young black hole feeds on a nearby sun-like star
Nobody can observe a black hole directly, which understandably makes it difficult to prove its existence. The best evidence we’ve found so far comes from binary star systems in which a visible star is trapped in orbit with a colossal but invisible predator. Observations like these have given astronomers the opportunity to track and analyze black holes based on their impact on surrounding stars and other light sources. Although only a handful of observations have been made of non-interacting black holes moving through star clusters, because of the boundaries inherent in “non-feeding” black holes.
In addition, there have never been direct detections of the dynamic effects of black holes in star clusters on the environment, which omits knowledge of the evolution of the monstrous singularities in such high-density stellar environments. Until now. The study authors, led by Sara Saracino of Liverpool John Moores University in the UK, have finally discovered a black hole in a globular cluster called NGC 1850 thanks to its interaction with a nearby star. The object, named NGC 1850 BH1, is quite young, only about 100 million years old. But it’s big.
A window into the childhood of black hole evolution
The newly discovered black hole is located in the Large Magellanic Cloud (LMC), a satellite galaxy of our own Milky Way. This latest discovery is part of a broader and systemic search for stellar mass black holes in young and giant star clusters within the LMC using multi-epoch MUSE (Multi-Unit Spectroscopic Explorer) observations carried out by ESOs (understandably huge) Very Large Telescope (VLT). The physics behind the new search involves variations in radial velocity. According to the study, the binary consists of a black hole which has about 11.1 times the mass of the sun, paired with a main sequence shutdown star (MSTO) which has about 4.9 times the mass of the sun.
It is also a semi-detached house and only has a period of about 5 earth days, together with an orbit inclination of 38 °. In particular, the researchers assume that the binary star system will experience a Roche Lobe overflow if the companion star evolves beyond its main sequence phase. This continues with “stable mass transfer and significant X-ray emission” as the distance between the binary elements increases. “The mass transfer is likely to end when most of the donor star’s hydrogen shell has been transferred to the companion or is lost from the system, leaving a helium star core,” the astronomers said in a press release. “If so, it will likely experience another phase of mass transfer (and X-rays) when the star helium burns in the shell and ends up as a black hole + white dwarf system.” In other words, the young black hole will continue to feed until its companion is reduced to the soft glow of a dying star: a white dwarf. This latest discovery could mark the beginning of a new study of young black holes while they are still in their “original mass function”, the early eons immediately after their formation. If we can broaden our analysis of more black holes at this early stage in their lives, we could improve our ability to spot others caught in a dance of death with nearby stars.