It all started when doctoral student David Narkevik reanalyzed data received six years ago at the Parkes radio telescope in Australia. Then he encountered a peculiar energy spike , a tremendous explosion that had lasted only 5 milliseconds at a distance of 1.5 billion light-years. The amount of energy thrown into space was immense : in that tiny space of time, as much energy was released as would be produced by the two Ascó nuclear power plants in Tarragona for 2 trillion years. Interestingly, this anomalous signal had been discovered by the astronomers who took the record of the observation at the time, but it was discarded because they believed that it was some type of terrestrial radio interference; They did not fit in their heads that such a phenomenal burst of energy had a cosmic origin. But it was. Although we must understand that it happened to them; as Matthew Bailes of Melbourne’s Swinburne University put it, “normally the kind of cosmic activity we look for at those distances is very faint, and this one was so bright that it saturated the instrumentation.”
Despite what the stillness of our night sky may suggest, the universe is not a quiet place , quite the contrary. There are stars that explode at the end of their days, becoming as luminous as all the stars in the Galaxy put together. But the most terrible explosions that we can observe are called Gamma Ray Bursts or gamma ray bursts (GRB) : on average, once a day, somewhere in the sky and for a period of time ranging from a fraction of a second to Within a few minutes, the universe treats us to a terrifying explosion in some distant galaxy: “something” shines as bright as 200,000 milky ways put together. Thus, on January 23, 1999, the X-ray and gamma-ray space observatories detected an impressive flare of energy at a point in the sky located in the constellation of Boyero . Two waves of radiation arrived at Earth 25 and 40 seconds after the explosion began. Then, for the next 50 seconds, other weaker pulses came. In the end there was calm. Calculated the energy released , the result is impressive: if it had happened just 2,000 light-years from us in the sky, a star twice as bright as our own Sun would have appeared.
Hidden behind those unappealing names astronomers use to catalog celestial events, GRB 990123 is an example of the worst explosions to happen in the universe since the Big Bang . GRBs were first detected on July 2, 1967 by the American satellites Vela 3 and Vela 4, which were intended to measure gamma radiation produced by Soviet nuclear tests. That day they detected a flash of gamma radiation whose structure did not conform to that which was usual for atomic explosions. We had to wait more than 30 years, for that January 23, 1999 , to be able to photograph this cataclysmic phenomenon and, thanks to it, identify its origin : a very faint galaxy located 9,000 million light-years away.
Its origin is unknown and there is no consensus on who or who can cause such explosions. Many astronomers think that they are collapsing objects , a process similar to -but hundreds of times more intense than- the supernova explosions that mark the end of a star’s life. No one knows how or why this happens, but it is thought to occur when the galaxy’s most massive stars collapse to form a rapidly rotating black hole, a process that lasts 10 to 20 seconds. Another hypothesis is that of the collision between two stellar corpses, the neutron stars. Imagining such an object is complicated: a star one and a half times the mass of our Sun crammed into a sphere ten kilometers in diameter and which rotates about a thousand times in a second.
This exotic collision – it is not easy for something like this to happen – is one of the explanations offered by the West Virginia University astronomer Duncan Lorimer, director of the group that found this unusual phenomenon. There is also an even more striking explanation proposed, that it is ” the last gasp of a black hole completely evaporating “. Lorimer is referring to what is known as Hawking evaporation , after the scientist who first described it, Stephen Hawking.
This explosion in the range of radio waves unsettled the whole world. Since its announcement, radio astronomers have directed their efforts to find more of these mysterious explosions , baptized as fast radio bursts (Fast Radio Burst, FRB) similar to the one that receives (erroneously) the name of “Lorimer burst” : strictly speaking, it should have the name of the student who discovered it, David Narkevik. This is reminiscent of the scandal that arose when the 1974 Nobel Prize in Physics for the discovery of neutron stars was given to Antony Hewish instead of the one who actually did it, his doctoral student Jocelyn Bell.
According to one of the JPL astronomers, Sarah Spolaor, “our team had to sift through data generated during 11 months of observation, which covered a wide area of the sky, to find them.” Spolaor was the scientist who developed the software to search for those elusive radio pulses and not to be confused with signals coming from mobile phones, airplanes … These explosions come from somewhere 11 billion light-years away, which makes it a process that took place when the universe was young , with about 4,000 million years of age.
What mysteries does this new phenomenon of FRBs hold? As with their cousins, the GRBs, none of the explanations offered (star colliding, black hole evaporation…) fit the scant data observed and therefore radio astronomers are preparing observation programs to discover more than these FRBs and shed light on their origin. As they say, the universe never ceases to amaze us.
