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Imagine one gigantic explosion that propagates in a perfectly spherical way. Seems unnatural, doesn’t it? Even the scientists who recently described it for the case of kilonova AT2017gfo, which took place in the galaxy Ngc4993, about 140 million light years from us, think the same. Yet, accounts in hand, this huge explosion first observed in 2017 it really seems to show this pattern. The discovery, precisely because it is apparently inexplicable, could provide us with gods alternative models for measuring the age of our Universe. The results are the result of a study by a group of researchers from the University of Copenhagen recently published on the pages of natures.
What is a kilonova
that it is ahuge astronomical explosion We’ve already said it, but why are we so interested? Kilonovae occur when two neutron stars that orbit around each other they end up colliding and merging, giving rise to a black hole and releasing a huge amount of energy. Neutron stars are basically what remains of stars once the nuclear fusion processes that fuel their cores have finished: very compact celestial bodieswhich usually measure no more than 20 kilometers in diameter but what can weigh up to twice the mass of the Sun. The clash between these celestial bodies, from which the kilonova is generated, concerns us more than we think because it gives rise to extreme physical conditions which allow you to create the heaviest elements of the periodic table – such as gold, platinum and uranium – by means of processes of nuclear fusion.
The mystery of sphericity
“Nobody – he has declared Darach Watson, associate professor at the Niels Bohr Institute and second author of the study – he expected the explosion to look like this. It doesn’t make sense that it’s spherical, like a ball. But our calculations clearly show that this is the case. This likely means that the kilonovae theories and simulations we have considered over the past 25 years lack important physics considerations.”. It took 6 years from the first measurements made, which, we recall, date back to 2017, to reach this mysterious conclusion. Those relating to kilonova AT2017gfo are also the only data of this type that we currently have and the authors point out that data from other such events will be needed to confirm their observations.
Also according to Albert Sneppen, first author of the study, all the intuitions and even the existing models would suggest that the explosive cloud that is generated by the collision has a flattened and rather asymmetrical shape. But that doesn’t seem to be the case. The researchers therefore stand formulating hypotheses that explain this unexpected behavior and which could among other things provide us with a new method for measuring distances between celestial bodies. This would also have some consequences for the way we use to measure the rate at which the Universe is expanding: “Among astrophysicists – explains Sneppen – there is much discussion about the rate of expansion of the Universe. Velocity tells us, among other things, how old is the Universe. The two existing methods of measuring it disagree by about a billion years. Here we might have a third method that can complement and be tested against the other measurements”. The kilonovae could be used as “a new kind of cosmic ruler”, as Watson defines it.
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