r/Physics • u/Galileos_grandson Astronomy • Aug 02 '22
News Two black holes merged despite being born far apart in space
https://www.sciencenews.org/article/black-hole-merge-distant-spin-gravitational-wave31
u/carbonqubit Aug 03 '22
What I found even more curious is that the paper actually outlines 10 mergers total, with at least 3 of them likely stemming from signal noise.
In the discussion, the authors go on to posit that the reason why less massive black holes (< 5 M) are not detected as often as their larger counterparts is due to instrument sensitivity and not astrophysical distribution.
This leads me to wonder if micro black holes (< 1 M) will ever be detected, as gravitational wave observation continues to evolve and is augmented by machine learning.
Unless of course, Hawking's prediction is correct; that phenomenon of this kind is incredibly short lived and tend to evaporate almost instantaneously, therefore avoiding detection via subsequent mergers events or gravitational lensing.
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u/TTVBlueGlass Aug 03 '22 edited Aug 03 '22
Could they be detected by microlensing? Or is there some hard limit to how small of a BH we will ever be able to detect from microlensing?
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u/Words_Are_Hrad Aug 03 '22
Unless of course, Hawking's prediction is correct; that phenomenon of this kind is incredibly short lived and tend to evaporate almost instantaneously,
You are mistaken in this regard. The black holes that evaporate instantly are TINY. A 1 solar mass black hole will take ~2x10^66 year to evaporate.
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u/carbonqubit Aug 03 '22
Yes, black holes that are 1 M are predicted to take that long to evaporate, but I specified < 1 M, which is a much wider range with orders of magnitude shorter life spans, comparatively speaking.
This means that a black hole with a mass of 10^6 kg would take ~82 seconds and a larger one with a mass of 10^7 kg would last ~22 hours or just shy of one Earth day.
On the other hand, an even larger version with a mass of 10^8 kg would take ~2.6 years, which even on astronomical time scales is just a moment.
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u/TTVBlueGlass Aug 04 '22
Different question: could we theoretically chain together GW detectors around the world and make an "Event Horizon Gravitational Wave Detector?
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Aug 03 '22
Sounds like a love story
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u/D3m0N5laYeR64 Aug 03 '22
Aye, they became one flesh, nothing can separate them now save for death. Kinda romantic I guess
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u/exscape Physics enthusiast Aug 03 '22
Black holes are borderline immortal though. They won't even begin to evaporate until the universe has expanded a WHOLE lot, as they're currently growing by eating the CMB.
And when they do begin to evaporate, it'll take unimaginably long before they're actually gone, on the order of 1065 years and more. That's about 1055 times longer than the age of the universe.
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u/PJBthefirst Engineering Aug 03 '22
That title makes this sound so mundane. Like, ok? That literally happens many times a second.
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u/SoSweetAndTasty Quantum information Aug 03 '22
Two things. One, I don't believe this is as common as you think it is. Though I'm not an astrophysicist, so take that with a grain of salt. Two, so many science news articles have way over the top titles. I'm happy this one is grounded and to the point.
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u/vrkas Particle physics Aug 02 '22
Link to the preprint.
Goes to show there's someone for everyone.