The representation of a microquasar event detected by the FAST Telescope. Credit: Thanks to Professor Wei Wang, Wuhan University
A global scientific collective has reported the unprecedented discovery of a quasi-periodic oscillation (QPO) signal in the radio band originating from a Galactic black hole system.
This international team of researchers has brought to light unique traits of a Galactic microquasar, GRS 1915+105, that were hitherto undiscovered. By leveraging an advanced telescope in China, they managed to pick up a quasi-periodic oscillation (QPO) signal in the radio band from microquasar systems for the first time ever. This newfound knowledge potentially presents the initial evidence of a “jet” propelled by a Galactic stellar-mass black hole. Further analysis is necessary to gain a comprehensive understanding of these fascinating signals.
Black holes are among the most enigmatic celestial bodies known to us, exhibiting features that seem to belong to the realm of science fiction.
For instance, stellar-mass black holes, about 10 times the mass of our sun, make their presence known by consuming matter from their partner stars. In certain situations, supermassive black holes amass at the core of galaxies, creating intensely bright, compact areas known as quasars, whose mass can be millions or even billions times that of our sun. A category of accreting stellar-mass black holes capable of launching jets of highly magnetized plasma are referred to as microquasars.
A team of scientists, including astrophysicist Bing Zhang from the University of Nevada, Las Vegas (UNLV), reported in the July 26 issue of Nature, a focused observational study on the Galactic microquasar named GRS 1915+105. The team uncovered aspects of a microquasar system that were previously unseen.
Utilizing the enormous Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China, the astronomers identified a quasi-periodic oscillation (QPO) signal in the radio band from a microquasar system, a first of its kind. QPOs are phenomena that astronomers employ to comprehend how stellar systems like black holes operate. While these have been detected in X-rays from microquasars before, their existence outside of this context — as part of the system’s radio emission — is distinctive.
“The unusual QPO signal has a rough period of 0.2 seconds, or a frequency of about 5 Hertz,” explained Wei Wang, a professor at Wuhan University in China who headed the team behind the discovery. “Such a signal doesn’t consistently exist and only appears under particular physical conditions. Our team was fortunate to catch the signal twice — in January 2021 and June 2022.”
According to UNLV’s Zhang, the director of the Nevada Center for Astrophysics and a co-author of the study, this unique feature might provide the first evidence of activity from a “jet” propelled by a Galactic stellar-mass black hole. Certain black hole binary systems launch a jet under specific conditions – parallel beams of charged matter and a magnetic field that move almost at light speed.
“X-rays generally probe the accretion disk around the black hole in accreting black hole systems, while radio emission usually investigates the jet launched from the disk and the black hole,” said Zhang. “The detailed mechanism to induce temporal modulation in a relativistic jet hasn’t been identified, but one plausible explanation could be the precession of the jet, meaning the jet direction consistently changes and returns to the original direction roughly every 0.2 seconds.”
Zhang suggested that a misalignment between the spin axis of the black hole and its accretion disk (extremely hot, bright spinning gasses surrounding the black hole) could produce this effect, a natural outcome of spacetime being dragged near a rapidly spinning black hole.
“Other potential explanations exist, though, and ongoing observations of this and other Galactic microquasar sources will provide more insight to comprehend these enigmatic QPO signals,” Zhang added.
Reference: “Sub-second periodic radio oscillation in a microquasar” by Pengfu Tian, Ping Zhang, Wei Wang, Pei Wang, Xiaohui Sun, Jifeng Liu, Bing Zhang, Zigao Dai, Feng Yuan, Shuangnan Zhang, Qingzhong Liu, Peng Jiang, Xuefeng Wu, Zheng Zheng, Jiashi Chen, Di Li, Zonghong Zhu, Zhichen Pan, Hengqian Gan, Xiao Chen & Na Sai, 26 July 2023, Nature.
DOI: 10.1038/s41586-023-06336-6
The article boasts 21 co-authors from 13 institutions, including UNLV and Wuhan University, and the National Astronomical Observatories of China (NAOC), along with various other observatories and universities in China.
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Table of Contents
Frequently Asked Questions (FAQs) about Galactic Black Hole
What is the new discovery made by the international team of scientists?
The team has discovered a unique quasi-periodic oscillation (QPO) signal in the radio band emanating from a Galactic microquasar system, GRS 1915+105. This is the first time such a signal has been detected from a microquasar system.
What could this discovery of QPO signal indicate?
The unique QPO signal might provide the first evidence of activity from a “jet” launched by a Galactic stellar-mass black hole. However, further observations and research are needed to confirm this hypothesis.
What is a microquasar?
A microquasar is a subset of accreting stellar-mass black holes that can launch jets of highly magnetized plasma. They are smaller counterparts of quasars, which are extremely bright, compact regions formed by supermassive black holes at the center of galaxies.
What telescope was used to detect this QPO signal?
The Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China was used to detect the QPO signal.
What do these QPO signals represent?
QPOs are phenomena used by astronomers to understand the functioning of stellar systems like black holes. This QPO signal has a rough period of 0.2 seconds, or a frequency of about 5 Hertz, and doesn’t consistently exist, appearing only under particular physical conditions.
4 comments
these scientists really deserve a pat on the back. Never thought id live to see the day we find evidence of “jet” activity from black holes. Brilliant!!
wait a min, so we’ve only detected QPO signals in x-rays till now? That’s a big step, detecting it in radio waves, ain’t it?
I can’t even begin to grasp what a black hole jet could be like. moving at near light speed, seriously? Space is wild, y’all!
Super interesting stuff, but I’m kinda lost on the technical bits. What exactly is a QPO and how does it relate to black holes? Anyone care to explain?