Gamma ray bursts are among the most mysterious phenomena in the universe. These gamma-ray bursts are usually divided into two types based on their length: long bursts lasting more than two seconds, while short bursts last less than two seconds. Is GRB 191019A a long, intermediate burst from a dying massive star, an abnormally long burst of colliding objects, or something else entirely?
Over time, as more data became available, experts linked this classification based on the length of the burst to the types of sources of the phenomenon: Long gamma-ray bursts appear to be associated with collapsed supernovae in the core of the Sun, when stars much more massive than our Sun expire. Their lives are short bursts of gamma rays and occur when two very dense celestial bodies, such as two neutron stars, collide. As more and more gamma-ray bursts appeared, the list of events that did not fall into either category increased.
In October 2019, a gamma-ray burst was observed that lasted more than a minute and at first glance appeared to be a traditional long supernova explosion. The object received signal GRB 191019A. The first explanation was later called into question because they could not observe the supernova emission associated with the explosion, the explosion itself was much fainter than expected, and in addition, the galaxy in which the event occurred did not have strong star formation. , although galaxies with long gamma-ray bursts usually are like this. These signals suggest that GRB 191019A may be part of a new type of gamma-ray burst that could be associated with colliding objects, although it is longer than two seconds.
In a recently published technical article, Robert Iles Ferris (University of Leicester) and colleagues examine a new possibility: GRB 191019A may not be a gamma-ray burst. According to researchers, this event was not caused by a supernova explosion or a cosmic collision, but by a single star that ventured close to a supermassive black hole and was suddenly torn apart in a tidal catastrophe.
Some features of GRB 191019A support this theory, such as its proximity to the galactic center. However, other factors, such as the duration of the event, tend to negate this: tidal disasters usually occur over months, not minutes. Iles-Ferris and his colleagues hypothesize that the explosion of GRB 191019A was not just a tidal catastrophe, but of the very deep kind, where the black hole's tidal force stretches the stricken star so much that it completely wraps itself around the black hole, collapsing in on itself while emitting a relativistic ray. .
Using a mathematical model, researchers showed that the brightness of GRB 191019A and the duration of the outburst are consistent with an extremely deep tidal catastrophe. If their theory is correct, this eruption could be the first extremely deep tidal catastrophe, and only the fifth to be accompanied by a particle beam. These events are very rare, but similar events will appear somewhere in the universe, and researchers already have a way to find them: they need to look for the low-energy X-rays that flash by the moment a star collides with itself.
The study announcing the research results was published in The Astrophysical Journal Letters, and here Readable.
source: AAS Nova
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