An Exotic Explanation for the Most Extreme Wave Detected so far – Universe Today

In Could of 2019, the wave observatories LIGO and Virgo detected the merger of two . One had a mass of 85 Suns, whereas the opposite was 66 photo voltaic plenty. The occasion was named GW190521 and was the most merger but noticed. It produced a 142 photo voltaic mass black gap, making it the primary gravitational wave remark of an intermediate mass black hole. However the occasion additionally raised a number of questions.

One of many greatest mysteries considerations the plenty of the 2 preliminary black holes. In keeping with stellar fashions, black holes shaped from the collapse of a big star can’t be bigger than about 65 photo voltaic plenty. Whereas the of the 2 may simply be underneath that restrict, the bigger is unquestionably not. So how did the 85 photo voltaic mass black gap kind?

One thought is that it’s the results of smaller mergers. If there an in depth system of four to six black holes, they could have merged over time to create a single massive black gap. However this cluster would additionally must be orbiting the 66 photo voltaic mass black gap for it to create the GW190521 merger. There’s some proof that black gap can exist, however whether or not they can merge shortly sufficient to elucidate GW190521 isn’t clear. So not too long ago a staff proposed a unique resolution. They suggest that the GW190521 wasn’t the merger of two black holes, however fairly a merger of two Proca stars.

The noticed merger occasion GW190521. Credit score: R. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration)

A Proca star, or boson star as it’s typically recognized, is a hypothetical object analogous to a white dwarf or neutron star. The constructing blocks of matter are available in two normal kinds: fermions resembling electrons and quarks, and bosons resembling gluons and the Higgs. Fermions resist occupying the identical quantum state. When gravity tries to squeeze fermions collectively, they push again by means of what’s known as degeneracy pressure. This stress is what retains white and neutron stars from collapsing underneath their weight.

Bosons haven’t any downside occupying the identical quantum state. In actual fact, when you super-cool bosons they’ll kind a single quantum object generally known as a Bose-Einsten condensate. Due to this, you may assume gravity would haven’t any downside collapsing a mass of bosons right into a black gap. But it surely seems that extraordinarily dense bosons in a robust gravitational discipline behave in sudden methods. The physics is fairly difficult, however the finish result’s {that a} boson star would attain an analogous gravitational standoff as white dwarfs and neutrons stars. Hypothetically, a boson star may very well be gravitationally steady similar to white dwarfs and neutron stars. Much more so. There’s a restrict to degeneracy stress, when signifies that white dwarfs can’t be bigger than 1.four photo voltaic plenty, and neutron stars might be bigger than 2 – three photo voltaic plenty. Given the precise circumstances, a boson star might simply have a mass of 85 Suns or .

A boson star as it could seem to the EHT. Credit score: Olivares et al

Recognized boson matter couldn’t grow to be a Proca star, however sure theories of darkish matter suggest new sorts of bosons. If darkish matter is made from low-mass bosons, they may kind into objects comparable in measurement and mass to black holes. Since they might have sturdy magnetic fields (not like black holes) we’d be capable to distinguish them from black holes by the way in which gentle lenses round them. Or, as this newest proposes, we’d be capable to detect them by their gravitational waves.

When the staff regarded on the information from the GW190521 occasion, they discovered that it was in step with each a black gap merger and a Proca star merger. The info matched each fashions equally effectively. Because the properties of a Proca star relies upon upon the mass of the bosons that make it up, they used the GW190521 information to measure the boson mass. The reply they received was extraordinarily tiny. A couple of trillionth that of the estimated neutrino plenty.

None of this proves that Proca stars exist. All of the gravitational wave occasions we’ve noticed are completely defined by black gap mergers. However the research presents us with fascinating concepts. A brand new gentle boson particle might assist us clarify darkish matter, and these darkish matter particles might kind into boson stars. It’s a weird thought, however one we will’t but rule out.

Reference: Bustillo, Juan Calderón, et al. “GW190521 as a Merger of Proca Stars: A Potential New Vector Boson of 8.7 × 10?13 eV.Bodily Evaluate Letters 126.8 (2021): 081101.

Reference: Brito, Richard, et al. “Proca stars: gravitating Bose–Einstein condensates of massive spin 1 particles.” Physics Letters B 752 (2016): 291-295.

Reference: Olivares, Hector, et al. “How to tell an accreting boson star from a black hole.Month-to-month Notices of the Astronomical Society 497.1 (2020): 521-535.



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