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trinitree88
2008-Oct-22, 06:26 PM
The authors revist the data from SN1987a and find a second set of coincidences between the neutrino detectors and gravitational wave detectors. see:http://arxiv.org/abs/0810.3759



It is interesting to note that the difference between ~50 milli lightseconds of interaction matter at SNO, and the amount needed on the hyperphysics site...~ a light year of lead for the rarer interaction of beta decay is a factor of ~ 600,000,000. Future results with improved statistics should clarify how that happens...the numbers as yet are still slim.

pete

Jerry
2008-Oct-23, 03:41 AM
At the time of the SN1987A the cryogenic resonant gravitational wave detec
tors were not ready yet, still in the construction phase. However in Rome the room-temperature resonant detector GEOGRAV, intended to detect signals correlated with the Earth movements, was in operation... On the next day, since GEOGRAV was in operation in the best possible noise condition, although this detector was not sensitive enough for a possible g.w. according to classical estimation of the cross-section, we carefully studied the data and found a correlation with the five-neutrino burst, with the g.w. signals anticipating the neutrino signals by 1.4 seconds.

This one badly fails the jerry test: If I claimed a receiver that was not nearly sensitive enough (by known constaints) provided evidence of a non-mainstream expectation, should or would anyone believe it?

trinitree88
2008-Oct-23, 09:49 AM
This one badly fails the jerry test: If I claimed a receiver that was not nearly sensitive enough (by known constaints) provided evidence of a non-mainstream expectation, should or would anyone believe it?

Jerry. I guess the issue will resolve around "classical" constraints. Given certain historical cross-sections, calculations indicate that the sensitivity was too low, hence the small regard for the initial statistics. However, discovery of other cross-sections, such as at SNO, in subsequent experimental apparatus may mean that the initial calculations were in error, and that revisiting the data will confirm that both sets of coincidences were real...or not. That's science. I'm not jumping up and down, but the results are interesting. The time delay between the events is most likely due to the lack of Universal time on all the apparatus at the date of the event...(according to Larry Sulak, principal ivestigator at the IMB,the IMB was set by somebody's watch, which people often do on the fly, or in their cars by the radio....after SN1987a, all apparatus were set to Universal Time accurately).
What is particulary interesting astronomically, is perhaps an indication of a two step core collapse, with two sets of neutrino bursts. That would mean, if the data pans out, that the gamma ray burst seen with the second stage is signaled by the first, and may give GRB astronomers a few hours advance notice of incoming bursts. That'd be nice for some progenitors. pete

Don Alexander
2008-Oct-24, 02:54 AM
That would mean, if the data pans out, that the gamma ray burst seen with the second stage is signaled by the first, and may give GRB astronomers a few hours advance notice of incoming bursts. That'd be nice for some progenitors. pete

Which GRB???

One associated with SN 1987A??? Puh-leeze!!! There is NO conclusive evidence for such an association, and no reason to believe one. The SN was completely wrong to be a GRB progenitor.

trinitree88
2008-Oct-24, 10:58 AM
Which GRB???

One associated with SN 1987A??? Puh-leeze!!! There is NO conclusive evidence for such an association, and no reason to believe one. The SN was completely wrong to be a GRB progenitor.

Don. The model of core collapse supernovae infers polar emission and axisymmetry. see:http://adsabs.harvard.edu/abs/2008AAS...212.1305M
That no instrument saw such a burst for 1987a does not mean that there was none, only that the orientation of the beaming was unfavorable, or that the instruments were busy elsewhere at the time....like opera singers with limited dynamic range, most satellites only monitor part of the electromagnetic spectrum... The only way GRB's can be reconciled with our understanding of energy generation is if they are pencil beamed (Shrinivas Kulkarni, MIT Physics Colloquiem talk on GRB's ~ 4 years ago).
Most supernovae are axisymmetric as evidenced by the axisymmetric remnants they leave, so the polar cap emission seen by Middleditch in the UV data is pretty normal. Matter traveling between 0.9c and 0.3c..(Middleditch's evidence, here) easily generates x-rays and gamma rays on impact with the ISM...just like cosmic rays do. pete. link:http://www.mpi-hd.mpg.de/hfm/HESS/public/PressRelease/DiffusePress/PressRelease_E.html

see also:http://www.hinduonnet.com/fline/fl1822/18220860.htm