Under certain conditions, some black hole binary systems launch a jet - a mix of parallel beams of charged matter and a magnetic field that moves with a swiftness approaching the speed of light. Our team was lucky enough to catch the signal twice - in January 2021 and June 2022, respectively."Īccording to UNLV's Zhang, director of the Nevada Center for Astrophysics and one of the study's corresponding authors, this unique feature may provide the first evidence of activity from a "jet" launched by a Galactic stellar-mass black hole. "Such a signal does not always exist and only shows up under special physical conditions. "The peculiar QPO signal has a rough period of 0.2 seconds, or a frequency of about 5 Hertz," said Wei Wang, a professor with China's Wuhan University who led the team that made the discovery. And while they have been observed in X-rays from microquasars, their presence outside of this manner - as part of the system's radio emission - is unique. QPOs are a phenomenon that astronomers use to understand how stellar systems like black holes function. Using the massive Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China, astronomers discovered a quasi-periodic oscillation (QPO) signal in the radio band for the first time from any microquasar systems. The team revealed features of a microquasar system that have never before been seen. A subset of accreting stellar-mass black holes that can launch jets of highly magnetized plasma are called microquasars.Īn international team of scientists, including UNLV astrophysicist Bing Zhang, reports in the July 26 issue of Nature a dedicated observational campaign on the Galactic microquasar dubbed GRS 1915+105. And in some instances, supermassive black holes accumulate at the center of some galaxies to form bright compact regions known as quasars with masses equal to millions to billions of our sun. Binary stars are pairs of stars sufficiently close to each other to be held together by their mutual gravitational attraction (like the Earth and the Moon), revolving in orbit around their common centre of gravity.Stellar-mass black holes with masses of roughly 10 suns, for example, reveal their existence by eating materials from their companion stars. Such pairs of stars are exceedingly common throughout the Universe. If, however, one of these stars collapses and becomes a compact object, like a neutron star or a black hole, its huge gravitational field, will cause matter to be drawn from the surface of its companion star sweeping it around into an accretion disk. The matter of this disk spirals faster and faster towards the centre and by dynamic friction reaches very high temperatures (typically 10 000 000 K), thus emitting X-rays and gamma-rays. There is still no definite proof that black holes exist, although there are many indications that black holes are a reality. Many interacting binaries are thought to be black hole candidates, as their supposed masses seem to be greater than the mass attributed to neutron stars. ![]() ![]() ![]() One expects binaries to behave differently according to whether the compact object is a neutron star or a black hole. Thanks to the greatly improved observational instruments used by INTEGRAL, astrophysicists hope to be able to distinguish one from the other through their gamma-ray emissions, thus, proving the existence of black holes. ![]() Next article: Galactic Centre > Galactic CentreĪs astronomers obtained the first precise measurements of gamma radiation from the centre of our galaxy, the Milky Way, they were surprised to find a high density of gamma-ray sources. These objects, possibly related to interacting binaries, further puzzled astronomers by their constant variation of intensity. Even more mysterious is the object hiding in the heart of our galaxy.
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