Captured The First Signal Preceding The Birth Of A Black Hole
The signal preceding the formation of a black hole has been discovered: it could be the first trace of the material that is about to be swallowed. The result, published in The Astrophysical Journal Letter, was obtained by an international research team led by Northwestern University and in which Italy participates with the University of Ferrara. The observations are based on data from NASA’s Chandra Space Telescope. The black hole in question was formed following the explosion of a kilonova, that is the explosive production of a large amount of radioactive material followed by the collapse of a newborn compact star, probably a neutron star, too massive to last longer to its own gravity. The explosion was observed on August 17, 2017 and occurred 130 million light-years from Earth. The subsequent collapse in the black hole, however, was not instantaneous: “it occurred after a time of about one second” explains Cristiano Guidorzi of the University of Ferrara and co-author of the study. Now, thanks to X-rays measured by NASA’s Chandra satellite, about 1,200 days after the catastrophic event, the signature of a new component, formed in that second, has been observed. According to the authors of the study, there are two hypotheses:
“It could be a sort of ‘sonic boom’ — continues Guidorzi — the result of the sudden deceleration of the radioactive material created in the moments immediately following the explosion and preceding the final collapse into a black hole. Or, it could be the first whimpers due to the material trapped in the accretion disk around the black hole “. Only future observations will clarify which of the two is the correct explanation.