22 candidate GW events within the first 4 month of O3

astro-marwil
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Topic 219394

Hallo!

New note from LIGO.

Good success and well within expectations.

How long will it take, to put them from candidate status to real event status? How many will be an artefact?

 

Kind regards and happy crunching

Martin

Mike Hewson
Mike Hewson
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I think there's some talk

I think there's some talk that the number of black hole mergers has been underestimated ie. if those 18 candidates for BH-BH become confirmed then that's rather more than the handful per year talked of a few years ago. Well, that's science of course : you look and you see. One line of thinking poses that larger groupings of BHs might abound eg. triplets and that's why we may be seeing all this merging. So how many black holes are out & about, if we only know of them via collisions ?! We live in exciting times ..... :-))

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

DanNeely
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I thought the few

I thought the few detections/year estimate was for the hardware at the sensitivity when they made the initial detections; with 1 or 2 a week being expected with the current level of upgrades.

Mike Hewson
Mike Hewson
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I should have quoted the

I should have quoted the source of my information : To Make Two Black Holes Collide, Try Three & the article it draws upon.

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

Rechenkuenstler
Rechenkuenstler
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Hi, there is a GW candidate

Hi,

there is a GW candidate in the O3 run GW190924h see https://gracedb.ligo.org/superevents/S190924h/view/

which is th first one classified as Massgap (>3 solar masses and <5 solar masses).

What does Massgap exactly mean in this sense? Is the resulting compact object within the massgap, or one or both merging objects. As far as I know, no such objects have been yet observed (no neutron stars > 3 solar masses, no black holes <5 solar masses). This would be the first one. Is it blackhole or neutron star?

 

Cheers

 

Bernhard

 

Mike Hewson
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Almost certainly it will be a

Almost certainly it will be a black hole : the upper limit ( theory plus observation ) places ~ 2.15 solar masses as that for neutron stars. If it is in the mass-gap ( and I guess 99% is pretty sure thing ) then this could be a marvelous find ie. what mechanism produced it ?

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

JStateson
JStateson
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Was recently reading about

Was recently reading about Primordial black holes.  Started at "Planet 9 is a black hole", then went to the UK's "Metro" and ended up at WiKi,  Unlike their Global Warming Discipline, the WiKi physics & math disciplines have no gatekeepers and I ran across the following sentence "...   However, if theoretical Hawking radiation does not actually exist.."

INCREDIBLE!  I had no idea that radiation was only theoretical!  If those primordial black holes cannot evaporate then dark matter can be explained!  Jumping to the WiKi for Hawking radiation I read where "CERN's Large Hadron Collider may be able to create micro black holes".   So, if the micro black hole cannot evaporate, what will happen to us if it "gets out of the lab"

Anyway, I see where researchers are looking for these tiny black holes and thought they found one in 2010: "Laser Makes Desktop Black Hole Glow".  But it seems to be just wishful thinking along the lines of cold fusion and room temp superconductors.

Hopefully these GW studies can shed some light on these tiny black holes.

[EDIT]  Seems like there are no observational evidence for Hawkins Radiation and "virtual particles" probably are hard to spot.  Faster than light travel is easy to spot  as it emits Cherenkov emissions which has been observed unlike Hawking theoretical mishmash.

Jim1348
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Quote:So, if the micro black

Quote:
So, if the micro black hole cannot evaporate, what will happen to us if it "gets out of the lab"

It would be fun to say that they gobble up Europe before reaching the U.S.  But since their mass is only as much as the energy put into them creates, I suppose that is overdoing it a bit.

Mike Hewson
Mike Hewson
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The mechanism of black hole

The mechanism of black hole radiation proposed by Mr Hawking is a conjecture and not yet observed. It's a pretty subtle effect and is proportional to the gravitational field strength at the event horizon. Counter intuitively the larger/massive the black hole is the lower that strength will be. Thus hypothetically, stellar mass black holes will take many times the current age of the Universe to evaporate, while tiny ones disappear in a instant. Now where do primordial black holes lie on this scale : could we see those dissipate in a burst of radiation ?

But that's if the radiation exists. It's not likely to be confirmed anyway. If one was observing nearby a black hole - and we on Earth aren't - you would have to distinguish such radiation from all the other goings on near black holes. It's not a bad idea per se, just untestable AFAIK.

As for laboratory based tiny black holes : what happens there depends upon <INSERT YOUR FAVORITE QUANTUM GRAVITY THEORY HERE>. If the LHC was going to make one they probably would have done so by now.

{ But probably not as the Schwarzschild radius of a proton is less than ~ 10-55 m }

Now here's a curious thing. What do black holes and elementary particles have in common ? They are both solely characterised by measurable mass, charge and spin. So maybe such particles are wee knots in spacetime already, huh ?

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

Kavanagh
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Mike Hewson wrote:I should

Mike Hewson wrote:

I should have quoted the source of my information : To Make Two Black Holes Collide, Try Three & the article it draws upon.

Cheers, Mike.

 

http://www.sci-news.com/astronomy/triple-supermassive-black-hole-07638.html

 

 

Richard

JStateson
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Kavanagh wrote:Mike Hewson

Kavanagh wrote:
Mike Hewson wrote:

I should have quoted the source of my information : To Make Two Black Holes Collide, Try Three & the article it draws upon.

Cheers, Mike.

http://www.sci-news.com/astronomy/triple-supermassive-black-hole-07638.html

 

Something wrong with that link, or the site is down, or (less likely) it is in my 0.0.0.0 host list that blocks google advs.

Quanta magazine reminds me of the Scientific American of the 60s before they got sokalized

Scrolling down to the bottom of the site for the videos

https://www.quantamagazine.org/

I watched the featured video "emergence" and then looked that definition up.  I had never heard that term before.  I had always wondering why everyone seems to be paying for their groceries a the same time and the previously empty check stands are now full.  Well, it cannot be predicted "a priori", it can only be observed which is the "principle of emergence".  

That site is on my reading list from now on and I passed the link on to my siblings and kids.

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