[vsnet-chat 2476] SN 1998bw and GRB 980425

[aah@nofs.navy.mil]

Berto drew our attention to this possible GRB/SNe association.
There has been much discussion on this case in the literature
and at meetings.  The background was that when the GRB went off,
SAX found two X-ray sources in the error box.  One was centered
on SN 1998bw; the other was a fading X-ray source (classical
counterpart to other GRBs).  This second source was ignored,
and the SNe was speculated to be the counterpart, especially
since the SNe occurred within a day or so of the GRB.  Many
models were produced, showing how a hypernovae (a more massive
star than a supernovae progenitor) could produce beamed gamma
rays, and spectra also showed 1998bw to be unusual.  Still,
the classical source was ignored.
  At the Huntsville meeting last month, several astronomers claimed
that the late time behavior of the OT light curves showed breaks
or humps that could be due to the OT fading, and an underlying
SNe light curve starting to appear.  Again, this is pure
speculation, and can be explained by a dozen other models.
Bottom line is that (a) there are probably several methods
by which gamma rays can be produced, and (b) there are almost as
many theories as there are astronomers working in the field.
Lots of fun!  I don't think there will be a concensus anytime
soon -- it will take a hundred OTs to get enough statistics
to rule out most of the current theories.  Meanwhile, it is
remarkable that, with small telescopes, we are able to see
optical sources that are many billions of light years away.
Arne

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