LONDON, 8 June – Gamma-ray bursts (GRBs), cosmic outbursts first detected by US military satellites in the late 1960s, have come to be understood as the brightest cosmic explosions in the universe. Typically, they are the result of the cataclysmic birth of a black hole in a distant galaxy, often through the collapse of a massive star.
Astronomers working in this field, including myself, are well aware of the tremendous energy scales involved in GRBs. These events can release as much energy in gamma rays as the Sun does in its entire lifetime. However, sometimes we come across a phenomenon that still astounds us.
In October 2022, the gamma-ray detectors on the orbiting satellites Fermi and Neil Gehrels Swift Observatory observed an extraordinary burst named GRB 221009a (named after the date of its detection). This outburst earned the nickname “The Boat” among astronomers because of its extraordinary brightness and refusal to fade like other outbursts.
The boat originated from a relatively close distance of 2.4 billion light-years, which is close by GRB standards. Even when accounting for this relativistic proximity, the energy and radiation produced by the event were off the charts. It is highly unusual for a cosmically distant event to deposit one gigawatt of power into Earth’s upper atmosphere.
Also read: Las Vegas Family Witnessing Aliens 2023
Brightest Cosmic Explosion
GRBs are known to launch boat-like narrow cosmic jets of gas into space, with material moving at speeds very close to that of light. The exact mechanism behind the launch of these jets is still somewhat intriguing, but it is likely to be linked to the magnetic field near the location where the black hole is forming.
The explosion we see is the initial emission from this jet. As time progresses, the jet slows down and produces additional radiation, resulting in a fading flash of light that can span a range of wavelengths, from radio waves to gamma rays in exceptional cases.
We do not directly observe the jets themselves. Instead, we see GRBs as points in the sky, similar to distant stars. However, there is strong evidence that GRBs do not explode equally in all directions. This would be unfair to GRB 221009A, as it would require multiplying the energy detected at Earth by that from all other directions, resulting in an energy output greater than that of any star.
Special relativity theory provides further indications that GRBs originate from jets pointing roughly in our direction. According to relativity, the speed of light remains constant regardless of the speed of the source relative to us. However, the direction of light may be distorted. This fun-house mirror effect causes light emitted in all directions from the surface of a fast-moving jet to be strongly concentrated in the direction of motion.
Even so, the edges of the jets headed toward us will be slightly curved, causing their light to be focused away from our direction. As the jet slows, the fringes gradually become visible, with the latter’s brightness fading rapidly.
However, GRB 221009A challenged these expectations. Its edges were never visible, and it joined a select group of very bright bursts that refuse to fade in the normal way. Instead of fading slowly and then quickly disappearing, the boat exhibited a steady decline in brightness over time.
In our study, published in Science Advances, we present an explanation for the unexplained appearance of jet edges that matches the boat’s observations. Our key insight is that when a narrow jet was launched, it had difficulty escaping the collapsing star, resulting in significant mixing with stellar gas at the edge of the jet.
To confirm this hypothesis, we conducted computer simulations that demonstrated this mixing process and incorporated it into a model for direct comparison with boat data. The simulations showed that what is usually a rapid decline in brightness turns into a long event.
The radiation emitted by the shock-heat gas of the dying star continues to intersect with our line of sight, explaining the continuing brightness of GRB 221009a. This phenomenon persisted until any distinctive jet signature was lost in the overall emission.
Thus, the observations of GRB 221009A not only validate predictions from our simulations but also provide insight into similar bright events observed in the past, where repeatedly adjusting energy estimates while waiting for the jet edge to appear Had to
Based on our calculations, the probability of seeing an explosion as bright as GRB 221009a is estimated to be approximately once every thousand years, making our observation incredibly lucky. However, many questions remain unanswered. For example, the role of magnetic fields in GRBs remains a subject of investigation. Theorists and numerical modelers will continue to delve into these matters, while carefully analyzing boat data
Unknown Facts of Brightest Cosmic Explosion
The brightest cosmic explosion, an unprecedented event in the universe, continues to baffle scientists with its mysterious features. Despite extensive research, there are still many unknown facts surrounding this extraordinary phenomenon. The extraordinary brightness of the explosion and its refusal to fade like other cosmic explosions have puzzled astronomers.
A puzzling aspect is the burst’s energy output, which is typically seen from events at such great distances. The sheer magnitude of power stored in Earth’s upper atmosphere raises questions about the underlying mechanisms driving this cosmic spectacle.
Furthermore, the precise process by which the burst’s narrow jets of cosmic gas are launched remains the subject of intense investigation. Scientists are working to understand the role of magnetic fields near the formation of black holes and their effect on the propulsion of these high-speed jets.
Another intriguing aspect is the continuous brightness of the burst. Unlike other bursts, which exhibit a predictable fading pattern, the brightest cosmic bursts appear to be gradually decreasing in brightness over time, defying conventional expectations. This phenomenon challenges existing theories and demands a deeper understanding of the underlying mechanisms at play.
To shed light on these unknown facts, scientists have turned to computer simulations and data analysis. By simulating the interaction between the collapsing star and the narrow jet, the researchers aim to explain the persistent brightness and elusive nature of the burst’s edges. These investigations provide important insights into the physical processes driving this cosmic spectacle.
Unraveling the deeply unknown facts of the most luminous cosmic explosion is key to unlocking the secrets of the universe and advancing our understanding of these awe-inspiring cosmic phenomena. Scientists are committed to exploring these enigmatic phenomena, striving to understand the underlying mechanisms and uncover the secrets hidden within the most spectacular cosmic explosions.