In stead of a dozen or so neutrinos in a moment, our detectors read "thousand and thousands" as Sagan would say, in a few seconds. How long does it take for astronomers to hear about it, and what do they do?

I would like to think that the receipt of so many neutrinos at once at any of the world's neutrino detectors would set off a klaxon horn and get somebody out of bed, get astronomical telegrams sent, etc. After all, this would be our first signal of a supernova in our galaxy. But I'm not sure that it is practical. After all, we still can't determine the direction of the incoming neutrinos, so there is no way to tell astronomers where to look for the supernova.

Of course, someone involved in neutrino research could correct me on this...

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Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.

I'm not in neutrino research, and your definition of direction is important, but we have some angular resolution with neutrino detectors. It's not great (i.e. we can see the sun, but we can't resolve it well), but it should be enough to find a nearby supernova. Such an event should be bright enough that all you need is a general direction.

Most neutrino events aren't directional, but a small fraction are. With thousands, the direction would be detectable. That being said, it would be better still if we had such detectors in several places (at least three) around the solar system, say the ones here on Earth, plus one on Mars, and on on Callisto. This would give excellent directional information without needing to sort out which neutrinos are directional. We could plausible have this set up before the end of the century.

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Forming opinions as we speak

If more than one neutrino detector 'up' at the time, and if they each had sufficient time resolution, the direction could be constrained to a plane; if three detectors (not in a line), then to two directions; etc. This is how the positions of (some) GRBs were (highly) constrained - time of detection by three or more widely separated detectors (some very widely separated - Ulysses, one of the martian probes, ...).

At least one of the neutrino detectors (AMANDA) could provide directions.

Do Type I supernovae blast out neutrinos?

A type Ia supernova can't produce such a blast of neutrinos because it blows itself up in a runaway fusion reaction (correct if I'm wrong). Other type I supernovae are special cases of core collapse supernovae and do create neutrinos.

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Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman

A reporting system for neutrino burst appears to exists.

http://www.iop.org/EJ/article/1367-2...jp4_1_114.html

Were the neutrinos from a low energy solar or high energy supernova event?

Hum,
you can work out the neutrino direction from the Cherenkov radiation in a typical detector like the Soudan experiment.

http://www.slac.stanford.edu/gen/mee.../wojcicki4.pdf

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`Irony` actually does mean `metal like`...

Or Sudbury or Super-Kamiokande. Of course, a burst that large might also overwhelm the detector by driving it beyond the event rate its data collection system can handle. That might drive us back on the time differential technique such as is used by GPS.

AMANDA has to be one of the coolest (in all senses of the word) experiments out there. I recommend its site to all interested.

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"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind." - William Thompson, 1st Baron Lord Kelvin

"If it was so, it might be, and if it were so, it would be, but as it isn't, it ain't. That's logic!" - Tweedledee

This isn't right. This isn't even wrong. - Wolfgang Pauli

How long does it take for the SN to start brightening after the neutrino flash?

Incidentally this thread gave me a fright
when I first saw it last week! Don't do it
again The story of the detection of the
1987a supernova will answer these questions.
The report in Sky & Telescope noted the
neutrinos gave a direction back to the event
with about +&- 20 degrees error as I remember.

The real answer is "we don't know yet"; a more considered answer is "between {a} and {b}, for {list of SN classes}".

Or, if you prefer, "the question needs to be refined quite a bit before any sensible answer can be given."

For example, in core collapse supernovae, the neutrinos exit, stage everywhere, within a second or so of them breaking through the traffic jam (for neutrinos) - about the same time as light takes to travel a distance equal to the radius of the star. At that time, the photosphere (which is pretty much what we see, of any star, in any electromagnetic waveband) is blissfully ignorant that the core has collapsed.

In some models, the collapse is asymmetric, and a 'polar jet' of relativistic particles blasts through the star's 'overburden', in approx the same time as the neutrinos - if we're 'looking down the jet', that's when the SN 'begins to brighten' (this may be what happens in 'long' GRB).

If 'begins to brighten' is about the same as 'when the photosphere starts to get ripped to pieces', then it's about as long as it takes the supersonic shock wave, of the rebound from the core collapse, to hit - seconds? minutes? probably not hours.

However, it may take much longer before someone 'looking down a telescope' could notice any brightening - no matter how hot the exploding star is, as long as its surface area (the part from which photons stream essentially free) is small, it won't be noticed.

So then the question resolves to something like "how long does it take for the expanding ball of star debris to become large enough that someone on Earth will notice it?"

[quote=Nereid;816585] Snippet:

In some models, the collapse is asymmetric, and a 'polar jet' of relativistic particles blasts through the star's 'overburden', in approx the same time as the neutrinos - if we're 'looking down the jet', that's when the SN 'begins to brighten' (this may be what happens in 'long' GRB).


Nereid. As a core collapse supernova is a weak interaction, and as the pulsar so formed has magnetic fields of the order of 10¹¹ to 10¹³ Gauss, the liklihood of a spherically symmetric collapse is slim. Parity effects in the prompt neutrino burst under such conditions prohibit a symmetric collapse as they are universally seen in weak interactions. One magnetic pole dominates the neutrino trapping, and the pulsar "births" out the other, in a giant analogous manner to the disintegration of spin polarized Co-60 by Wu, Ambler, confirming the theoretical musings of T.D.K.Lee and C.N.Yang.
The inherent asymmetry leads to a shift in the center of mass, and hence a gravitational wave is expected. Failure to detect future G-waves coincident with future prompt neutrino bursts from closer-than-threshold-events should mean symmetrical events. Detection of such should confirm parity effects, and asymmetry. Pete.

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A third rate theory forbids
A second rate theory explains after the fact
A first rate theory predicts...A. Lomonosov