A basic introduction to Astrophysics - Page 5

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.107.111101

Anyways, 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.

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.

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.

On April 27 2015 06:08 opisska wrote:


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.

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...

On April 27 2015 06:18 Maenander wrote:

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...

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.

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.

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

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 :[