Subject: new paper on SN location by neutrinos
From: John Beacom (beacom@citnp3.caltech.edu)
Date: Wed Dec 02 1998 - 20:17:21 EST
Kate Scholberg suggested that I announce to the SNNET mailing list
that Petr Vogel and I have a paper out on the usefulness of various
techniques for locating a supernova by its neutrinos. Some of this
material was first presented at the Boston workshop in September.
I would appreciate hearing any comments that you may have.
Thanks,
John Beacom beacom@citnp.caltech.edu
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The paper can be found at this URL:
http://xxx.lanl.gov/abs/astro-ph/9811350
Can a supernova be located by its neutrinos?
J. F. Beacom, P. Vogel (Caltech)
A future type-II supernova in our Galaxy will be detected by several
neutrino detectors around the world. The neutrinos escape from the
supernova core over several seconds from the time of collapse, unlike
the electromagnetic radiation, emitted from the envelope, which is
delayed by a time of order hours. In addition, the electromagnetic
radiation can be obscured by dust in the intervening interstellar
space. The question therefore arises whether a supernova can be
located by its neutrinos alone. The early warning of a supernova and
its location might allow greatly improved astronomical observations.
The theme of the present work is a careful and realistic assessment of
this question, taking into account the statistical significance of the
various neutrino signals. Not surprisingly, neutrino-electron forward
scattering leads to a good determination of the supernova direction,
even in the presence of the large and nearly isotropic background from
other reactions. Even with the most pessimstic background
assumptions, SuperKamiokande (SK) and the Sudbury Neutrino Observatory
(SNO) can restrict the supernova direction to be within circles of
radius $5^\circ$ and $20^\circ$, respectively. Other reactions with
more events but weaker angular dependence are much less useful for
locating the supernova. Finally, there is the oft-discussed
possibility of triangulation, i.e., determination of the supernova
direction based on an arrival time delay between different detectors.
Given the expected statistics we show that, contrary to previous
estimates, this technique does not allow a good determination of the
supernova direction.
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