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On April 27 2015 05:22 Mordanis wrote:While thinking about this, I came across this article. Might be the coolest thing I've ever heard of. http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.107.111101Anyways, it looks like about 7 evaporation events have been observed as of 1995. Here's a link to an article. The article is behind a paywall, but you can look at the first two pages if you click "look inside". It seems like black hole evaporation describes some, but not all, GRBs.
The idea that some GRBs are PBH evaporation events is very, very fringe in the GRB community as far as I know. I have never heard it from anyone from the GRB group I losely work with even mentioned as a possibility.
Everyone really needs to keep in mind that however engrained in the popular culture, Hawking radiation is still purely theoretical.
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A black hole evaporation event has to be pretty faint.
How much mass does a black hole retain until the last second of its life? ~ 1000000 kg or so ? Hence 1000000 kg/s * c^2 is the largest luminosity it will ever reach over a full second.
It would have to be to be pretty close to be observable, and would certainly not be red-shifted by the expansion.
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Italy12246 Posts
On April 27 2015 05:36 opisska wrote:The idea that some GRBs are PBH evaporation events is very, very fringe in the GRB community as far as I know. I have never heard it from anyone from the GRB group I losely work with even mentioned as a possibility. Everyone really needs to keep in mind that however engrained in the popular culture, Hawking radiation is still purely theoretical.
Yep, most of the GRB community is pretty convinced by the Hypernova models. SN1998bw is the most important event supporting that interpretation, but there's plenty more. We have detected hundreds of GRBs, so explaning 7 of them is situational at best
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On April 27 2015 05:52 Maenander wrote: A black hole evaporation event has to be pretty faint.
How much mass does a black hole retain until the last second of its life? ~ 1000000 kg or so ? Hence 1000000 kg/s * c^2 is the largest luminosity it will ever reach over a full second.
It would have to be to be pretty close to be observable, and would certainly not be red-shifted by the expansion.
The article linked above specifically notes that while most conservative models predict lower burst output, there are feasible models where the final burst releases 10^9 to 10^14 grams of rest energy - the whole uncertainity comes about when the QCD effects kick in.
Anyway, thinking about it, the paper is from before any real optical counterparts with spectra were known, thus before the cosmological distibution of GRBs was established, making the point probably moot with today's knowledge.
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Also, fuck GRBs in general. Among other things, we are running a small robotic telescope in the southern hemisphere which is set up to do GRB follow-ups and the last big hit occured 3 years before I joined the team, so I don't get a high-profile GRB publication (there is one with "GRB" in title that I have written, but that merely describes the patient wait we are currently exhibiting).
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Italy12246 Posts
haha :D imagine how the people hoping to detect neutrinos from a supernova in the Milky Way must feel then...
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On April 27 2015 06:08 opisska wrote:Show nested quote +On April 27 2015 05:52 Maenander wrote: A black hole evaporation event has to be pretty faint.
How much mass does a black hole retain until the last second of its life? ~ 1000000 kg or so ? Hence 1000000 kg/s * c^2 is the largest luminosity it will ever reach over a full second.
It would have to be to be pretty close to be observable, and would certainly not be red-shifted by the expansion. The article linked above specifically notes that while most conservative models predict lower burst output, there are feasible models where the final burst releases 10^9 to 10^14 grams of rest energy - the whole uncertainity comes about when the QCD effects kick in. Anyway, thinking about it, the paper is from before any real optical counterparts with spectra were known, thus before the cosmological distibution of GRBs was established, making the point probably moot with today's knowledge. Yeah sorry, was just going through the wiki equations and not looking at the article. Even optimistic 10^14 grams is not that much, given the sun puts out ~ 4 x 10^12 g/s.
On April 27 2015 06:16 Teoita wrote: haha :D imagine how the people hoping to detect neutrinos from a supernova in the Milky Way must feel then...
How lucky were Kepler and Tycho? One supernova for each of them, both easily visible for the naked eye.
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On April 27 2015 06:18 Maenander wrote:Show nested quote +On April 27 2015 06:08 opisska wrote:On April 27 2015 05:52 Maenander wrote: A black hole evaporation event has to be pretty faint.
How much mass does a black hole retain until the last second of its life? ~ 1000000 kg or so ? Hence 1000000 kg/s * c^2 is the largest luminosity it will ever reach over a full second.
It would have to be to be pretty close to be observable, and would certainly not be red-shifted by the expansion. The article linked above specifically notes that while most conservative models predict lower burst output, there are feasible models where the final burst releases 10^9 to 10^14 grams of rest energy - the whole uncertainity comes about when the QCD effects kick in. Anyway, thinking about it, the paper is from before any real optical counterparts with spectra were known, thus before the cosmological distibution of GRBs was established, making the point probably moot with today's knowledge. Yeah sorry, was just going through the wiki equations and not looking at the article. Even optimistic 10^14 grams is not that much, given the sun puts out ~ 4 x 10^12 g/s.
Sure, the point was that these things could be pretty ubiquituous and thus the bursts would be happening rather close to us - which is, I believe, considered quite unlikely now.
On April 27 2015 06:16 Teoita wrote: haha :D imagine how the people hoping to detect neutrinos from a supernova in the Milky Way must feel then...
They are probably still dreaming about 1987
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Italy12246 Posts
There's a detector at the labs in Gran Sasso made specifically for that, that started functioning like one month after that supernova. There hasn't been one close enough since.
And yeah, if the black hole evaporation models predict they are that faint, there's no way they can be correct.
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On April 27 2015 06:28 Teoita wrote: There's a detector at the labs in Gran Sasso made specifically for that, that started functioning like one month after that supernova. There hasn't been one close enough since.
LOL I didn't know that, what a story!
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Italy12246 Posts
The funny part is it's still functional, they are all thinking "come on some of you fuckers blow up, you've taken enough time already!"
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Well, it's like waiting for some nucleus with a half life of a hundred years or so to pop.
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On April 27 2015 06:40 Maenander wrote: Well, it's like waiting for some nucleus with a half life of a hundred years or so to pop.
Of those you can just bring a couple of billion and you are golden
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Great read, thanks for posting
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First, amazing blog! I have a strong passion for Physics education so I'm always happy to see people explain difficult concepts in an approachable way.
On April 26 2015 18:34 eonrulz wrote:Great blog, Teoita. Nice to see science getting its due attention on TL :D Maybe I should write a similar blog for particle physics/quantum mechanics. That's my field, after all. Would be a nice accompaniment to this blog - the large and the small! Plus there do seem to be a lot of misconceptions about QM floating around this thread
I'm have a graduate degree in Experimental Nuclear!
We should put together a series of blogs for TL! :D
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Mute City2363 Posts
I took an astrophysics module as part of my maths course, but was too shit to think about continuing on that line though. It's really interesting stuff though; yet another part of applied maths I wish I was more competent at :[
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United States4883 Posts
The Hubble is a PoS! Get that thing outta orbit, it's not doing anything useful up there!
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28076 Posts
On April 27 2015 14:45 thecrazymunchkin wrote: I took an astrophysics module as part of my maths course, but was too shit to think about continuing on that line though. It's really interesting stuff though; yet another part of applied maths I wish I was more competent at :[ Yeah it's extremely daunting. I've taken some physics/astro classes as electives and I think I could have managed to fight my way to a degree in it, but it would have been really hard, and I would never compare to some of the talented people in those classes who just understood stuff like it was no big deal.
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