Yet another oldest Supernova ever

On Jul 10, 12:07*pm, Sam Wormley wrote:
[...]

* *Have you considered that the GRB might result from something
* *other than a supernova explosion. Did you compare the energy
* *levels?

It is very likely that GRBs are the product of a supernova, we just
don't know for sure yet.

Steve Willner wrote:
In article ,
Yousuf Khan writes:
didn't they announce the oldest, farthest Gamma-Ray Burst, which would
also be a type of supernova. And the GRB was farther away still, at over
13 billion light-years.

I think the difference -- as you indicate in a later message -- is
that GRBs are not known to be supernovae.

A difference that is of considerable practical interest is that
intrinsic luminosities of GRBs are not known even crudely. That
makes cosmological tests using GRBs impossible. Mind you, I'm not
sure luminosities for Type IIn SNe are known well enough to do
cosmology, but at least there's some hope for those.


Well, some GRB's are thought to be the result of supernovas that have
their axes pointed directly toward us by chance. Not all supernovas have
their explosion axes pointed toward us, that's why we don't see them all
as GRB's.

Yousuf Khan

On Jul 10, 4:08*pm, Sam Wormley wrote:
I think in this case, they did identify this GRB as a supernova. I
guess the other possibilities for GRBs are Active Galactic Nucleii.
AGN's are usually long-duration, while supernovas are short duration
GRBs.

* *...or merging black holes.

But I think a merging black hole or neutron star would produce very
short duration gamma rays, a few seconds at most.

Yousuf Khan

Sam Wormley wrote:
But I think a merging black hole or neutron star would produce very
short duration gamma rays, a few seconds at most.

Yousuf Khan


http://imagine.gsfc.nasa.gov/docs/sc...l1/bursts.html
followed by

http://imagine.gsfc.nasa.gov/docs/sc..._duration.html
followed by

http://imagine.gsfc.nasa.gov/docs/sc...explosion.html
followed by

http://imagine.gsfc.nasa.gov/docs/sc...explosion.html
followed by

http://imagine.gsfc.nasa.gov/docs/sc...mysteries.html

So according to your link, the dividing line between long GRB's and
short GRB's is 1 or 2 seconds. If it's a long GRB, then it's likely a
supernova, otherwise it's a black hole/neutron star merger.

According to emails exchanges between NASA experts, the duration is
about 1.1 to 1.3 seconds in duration, which leads them to believe it's
closer to a long burst, thus of supernova origins.

"When converted to the rest frame, the T90 values (10.3 ± 1.1 sec,
Swift/BAT 15-350 keV, Palmer et al., GCN 9204) and (12 sec, Fermi/GBM
8-1000 keV, Kienlin, GCN Circ. 9229) transform to 1.1 ± 0.1 sec and 1.3
sec, respectively. However, one must be careful in comparing these
numbers to the BATSE short-hard burst divide (Kouveliotou et al., ApJ
413, L101, 1993). The BATSE duration distribution is in the observer
frame. With a typical redshift of z = 1-2 for BATSE bursts, the dividing
line between long and short in the rest frame is 0.7 to 1.0 seconds.
Thus this burst is on the boundary and toward the long side. "
http://gcn.gsfc.nasa.gov/other/090423.gcn3