Stars with a mass over ten times that of the Sun often go through explosive death throes, turning into black holes and emitting brief, erratic gamma-ray bursts that can only be observed using space telescopes. In-depth exploration of these bursts and their associated optical radiation, such as those found in 2021’s GRB 210619B, has yielded invaluable insights into the mechanics of these stellar explosions and the conditions they generate.
In addition, a bright optical emission was also identified.
Joseph Shklovsky, a pioneer of contemporary astrophysics, proposed that a star’s life is a continuous battle between two opposing forces: gravity, which attempts to compress the star, and the counteracting gas pressure that strives to disperse it. Once the thermonuclear reactions that fuel the star’s core end, the star loses its ability to maintain equilibrium and starts to implode into a single point.
When this situation involves a star more than ten times the mass of our Sun, the core contracts and the outer shell is violently disrupted. This causes an incredibly powerful explosion on a cosmic scale, signifying the transformation of the most massive stars into black holes.
These explosions are marked by an intense burst of gamma radiation — a stream of photons with energy millions of times greater than the visible light quanta we are used to.
A gamma-ray burst is a fleeting and unpredictable phenomenon, with durations from less than a second to several hundred seconds. There is no way to foretell exactly where in the sky and when a gamma-ray burst will occur. Moreover, due to the Earth’s atmosphere blocking gamma radiation, gamma-ray bursts can only be spotted with the use of space telescopes.
Gamma-ray bursts have been observed since the late 1960s. For a long time, scientists only recorded the gamma radiation that is invisible to the naked eye. However, it was suggested that these bursts might also have observable optical radiation. This was indeed confirmed for the first time on January 23rd, 1999.
To promptly detect optical radiation, scientists have engineered robotic telescopes capable of collecting real-time data directly from the burst’s location. On June 20th, 2021, GRB 210619B, one of the most intense gamma-ray bursts recorded so far, was observed using telescopes situated in the Czech Republic, Spain, and the Russian Mini-MegaTORTORA system owned by Kazan Federal University and located in the North Caucasus. These telescopes started recording the bright afterglow 28 seconds after the gamma-ray flash. Simultaneous data from three telescopes allowed the reconstruction of the light curve’s overall shape, the slope of the optical spectrum at various times, and the early multiband evolution of the optical radiation.
Anton Biryukov, co-author of the study and Associate Professor of the HSE Faculty of Physics, described the event as nearly unique, pointing out the bright afterglow, the high temporal resolution with frequent frames, and the information about the optical radiation spectrum obtained. They were able to conduct observations using a set of optical filters in the Mini-MegaTORTORA system, measuring not just the overall brightness but also the brightness in specific colors.
The availability of detailed data across various wavebands, including the optical range, facilitated determining the physical parameters of the medium linked with the gamma-ray burst where the optical radiation originated. Biryukov explained that this extensive dataset allowed them to delve into the inner workings of gamma-ray bursts, revealing the moving particles, their energy levels, the density of the surrounding medium, and the magnetic fields’ characteristics.
The authors of the study concluded that the luminous phenomena observed during a gamma-ray burst result from the movement of high-energy charged particles, almost at the speed of light, within a rarefied medium dominated by a strong magnetic field.
Biryukov explained that gamma-ray bursts act as lighthouses from the early universe, shining light on stellar activities billions of years ago, including their deaths, the interstellar environment around them, and interactions with stellar ejecta.
Yet, studying gamma-ray bursts not only expands our understanding of distant massive stars. From a basic physics perspective, gamma-ray bursts act as natural physics labs that display the most extreme conditions possible, encompassing ultra-high energies, velocities, densities, and gravitational forces. These conditions allow scientists to test the physical theories known to us.
Andrey Biryukov asserted that our current fundamental theories, such as the theory of relativity and quantum mechanics, have their inherent limits, which can only be determined experimentally using phenomena like gamma-ray bursts. Detecting these limits is challenging, requiring continuous observations and comprehensive descriptions of as many similar events as possible. However, this aligns with the natural progression of scientific knowledge.
The findings were published in the paper “Exceptionally bright optical emission from a rare and distant gamma-ray burst” by a team of researchers in the May 2023 edition of Nature Astronomy.
DOI: 10.1038/s41550-023-01972-4
Table of Contents
Frequently Asked Questions (FAQs) about Gamma-Ray Bursts
What are gamma-ray bursts and how are they formed?
Gamma-ray bursts are brief, erratic emissions of gamma radiation that occur when stars over ten times the mass of the Sun undergo cataclysmic explosions, transforming into black holes. These bursts are marked by a stream of photons carrying energy millions of times greater than visible light.
Who is Joseph Shklovsky and what is his theory about stars?
Joseph Shklovsky is a pioneer of contemporary astrophysics. He proposed that a star’s life is a continuous battle between two opposing forces: gravity, which attempts to compress the star, and the counteracting gas pressure that strives to disperse it. Once the thermonuclear reactions that fuel the star’s core end, the star loses its ability to maintain equilibrium and starts to implode into a single point.
What significance does the observation of gamma-ray bursts hold for the scientific community?
The observation of gamma-ray bursts helps expand our understanding of the most massive distant stars. These bursts serve as natural physics laboratories that manifest the most extreme conditions imaginable, encompassing ultra-high energies, velocities, densities, and gravitational forces. These conditions allow scientists to test the physical theories known to us, and can also provide us with insights about the workings of stars billions of years ago and how their existence ended.
What is GRB 210619B?
GRB 210619B is one of the most powerful gamma-ray bursts documented to date, observed on June 20th, 2021. The detailed study of its burst and associated optical radiation has provided invaluable data about the mechanics of star explosions and the conditions they create.
What are the limits of existing fundamental theories like the theory of relativity and quantum mechanics?
According to Andrey Biryukov, existing fundamental theories like the theory of relativity and quantum mechanics have inherent limits of applicability. These limits can only be experimentally determined. Phenomena like gamma-ray bursts serve as natural experiments to help detect these limits. However, detecting these limits requires continuous observations and comprehensive descriptions of as many similar events as possible.
More about Gamma-Ray Bursts
- Gamma-Ray Bursts
- Joseph Shklovsky and his contributions to Astrophysics
- GRB 210619B
- Theory of Relativity
- Quantum Mechanics
2 comments
guys, isn’t it incredible how gamma-ray bursts can help us to test our theories about the universe? nature’s very own physics lab, so cool!
damn, this is heavy… stars over ten times the mass of our sun transforming into black holes with explosive bursts of gamma radiation… gives me chills!