A recent massive gravitational event could have been a collision of primordial black holes
On May 21, 2019, gravity observatories detected the most massive gravitational event to date, known as GW190521. According to the prevailing hypothesis, it was a collision of black holes with masses of 85 and 66 Suns, which is problematic for existing supernova theories. Therefore, more exotic explanations are emerging, such as the latest hypothesis about the collision of primordial black holes.
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The most massive gravitational event. Credit: D. Ferguson, K. Jani, D. Shoemaker, P. Laguna, Georgia Tech, MAYA Collaboration).
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In September 2020, a large global team of gravitational astronomers LIGO / Virgo collaboration announced the detection of gravitational waves that came to us from the most massive collision of two objects so far. The event, designated GW190521, attracted much attention and a number of hypotheses emerged. The detection itself occurred on May 21, 2019.
Antonio Riotto. Credit: University of Geneva.
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According to the predominant one, it was a collision of two black holes, of which at least the more massive one is quite problematic. These should be black holes with a mass of 85 and 66 Suns, and their collision would create a black hole with a mass of 142 Suns. The remaining mass corresponding to 9 Suns in that collision radiated in the form of gravitational waves. Pair-instability supernova theory predicts “forbidden” mass gaps of black-sized black holes, and the more massive black hole of GW190521 just mentioned should have just that mass.
Antonio Riotto from the Swiss Université de Genève and his colleagues recently analyzed the data of event GW190521 and came up with another exotic hypothesis.
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Event detection GW190521. Credit: R. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration).
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According to them, it could be a collision not of black holes created by the collapse of massive stars, but a collision of primordial black holes, which should be a remnant of a very early universe. Primordial black holes easily circumvent the problem with the “forbidden” masses of black holes in the aforementioned supernova theory.
To this end, it should be noted that primordial black holes are still completely hypothetical. What’s more, it doesn’t look very good with their existence, as long as the enchanted layman can judge. However, as can be seen, they still have their supporters. Riotto et al. they calculated and modeled it, taking into account the presumed properties of primordial black holes as well as the properties of already confirmed phenomena, such as relic cosmic microwave background radiation (CMB). In the end, they realized that it might indeed be a collision of primordial black holes.
And maybe that won’t be all. Riotto and colleagues intend to look for other possible cases where the detected gravitational waves could come from the collision of primordial black holes. They will analyze existing and of course future data from gravity observatories.
Video: GW190521 The Impossible Black Hole
Literature
Physical Review Letters 125: 101102.
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