Gamma Ray Bursts -- Fireballs or Cannonballs?

(Jim Graber) writes:

Has anyone else been paying any attention to the fireball versus
cannonball dispute?
It seems to me the cannonball guys have some fairly strong points, but
no one else seems to agree. Why is this? Is there a fatal flaw in
their argument? Why are fireballs so popular?

First of all, I think the term "fireball" is now being used in a rather
"generic" sense, such that it is essentially equivalent to "afterglow."

Secondly, under the "hypernova" model, wherein a massive rotating incipient
black hole formed during an otherwise normal core-collapse supernova fires
a pair of relativistic beams along its axis, the "fireball" and "canonball"
models have effectively merged into each other...


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

(Jim Graber) writes:

Has anyone else been paying any attention to the fireball versus
cannonball dispute?
It seems to me the cannonball guys have some fairly strong points, but
no one else seems to agree. Why is this? Is there a fatal flaw in
their argument? Why are fireballs so popular?

First of all, I think the term "fireball" is now being used in a rather
"generic" sense, such that it is essentially equivalent to "afterglow."

Secondly, under the "hypernova" model, wherein a massive rotating incipient
black hole formed during an otherwise normal core-collapse supernova fires
a pair of relativistic beams along its axis, the "fireball" and "canonball"
models have effectively merged into each other...


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

(Jim Graber) wrote in message ...
Has anyone else been paying any attention to the fireball versus
cannonball dispute?
It seems to me the cannonball guys have some fairly strong points, but
no one else seems to agree. Why is this? Is there a fatal flaw in
their argument? Why are fireballs so popular?
Inquiring minds want to know...
TIA
Jim Graber


wasn't the cannon ball model ruled out last May? At least this is what the
press release says:
at least this is what I am inferring from the following press release:
http://www.nrao.edu/pr/2003/grb030329/
Or am I reading too much into this?
anyhow can some expert comment?
melroy

(Jim Graber) wrote in message ...
Has anyone else been paying any attention to the fireball versus
cannonball dispute?
It seems to me the cannonball guys have some fairly strong points, but
no one else seems to agree. Why is this? Is there a fatal flaw in
their argument? Why are fireballs so popular?
Inquiring minds want to know...
TIA
Jim Graber


wasn't the cannon ball model ruled out last May? At least this is what the
press release says:
at least this is what I am inferring from the following press release:
http://www.nrao.edu/pr/2003/grb030329/
Or am I reading too much into this?
anyhow can some expert comment?
melroy

(Melroy) writes:

(Jim Graber) wrote in message ...
Has anyone else been paying any attention to the fireball versus
cannonball dispute?
It seems to me the cannonball guys have some fairly strong points, but
no one else seems to agree. Why is this? Is there a fatal flaw in
their argument? Why are fireballs so popular?
Inquiring minds want to know...

wasn't the cannon ball model ruled out last May? At least this is what the
press release says:
at least this is what I am inferring from the following press release:
http://www.nrao.edu/pr/2003/grb030329/
Or am I reading too much into this?
anyhow can some expert comment?

I don't think so. One of the implications of the "hypernova" model is that
due to relativistic effects, the gamma-ray bursts are _HIGHLY_ beamed,
with opening angles of less than ten milliradians (about 1/2 a degree).
We would only an "ordinary" Type Ia "supernova" unless the rotation axis of
the nascent black hole from the hypernova happens to be pointing almost
DIRECTLY at us --- in which case no significant "proper motion" would be
observed. The recent observation by Coburn and Boggs that the gamma rays
from a GRB are highly polarized (~80%), strongly supports the "hypernova"
model, and strongly disfavors the "fireball" model, which does not have
any preferred axis along which to polarize the gamma-rays, and which
predicts polarizations of less than a few percent.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

(Melroy) writes:

(Jim Graber) wrote in message ...
Has anyone else been paying any attention to the fireball versus
cannonball dispute?
It seems to me the cannonball guys have some fairly strong points, but
no one else seems to agree. Why is this? Is there a fatal flaw in
their argument? Why are fireballs so popular?
Inquiring minds want to know...

wasn't the cannon ball model ruled out last May? At least this is what the
press release says:
at least this is what I am inferring from the following press release:
http://www.nrao.edu/pr/2003/grb030329/
Or am I reading too much into this?
anyhow can some expert comment?

I don't think so. One of the implications of the "hypernova" model is that
due to relativistic effects, the gamma-ray bursts are _HIGHLY_ beamed,
with opening angles of less than ten milliradians (about 1/2 a degree).
We would only an "ordinary" Type Ia "supernova" unless the rotation axis of
the nascent black hole from the hypernova happens to be pointing almost
DIRECTLY at us --- in which case no significant "proper motion" would be
observed. The recent observation by Coburn and Boggs that the gamma rays
from a GRB are highly polarized (~80%), strongly supports the "hypernova"
model, and strongly disfavors the "fireball" model, which does not have
any preferred axis along which to polarize the gamma-rays, and which
predicts polarizations of less than a few percent.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

I wrote, regarding the current "hypernova" model of GRBs:

[...] We would only see an "ordinary" Type Ia "supernova" unless the rotation axis
^^^^^^^^^
I'm sorry, that should have read "Type II," not "Type Ia." (I guess I have typed
"Type Ia" a few too many times, and it has now become a semi-automatic reflex... :-(


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

I wrote, regarding the current "hypernova" model of GRBs:

[...] We would only see an "ordinary" Type Ia "supernova" unless the rotation axis
^^^^^^^^^
I'm sorry, that should have read "Type II," not "Type Ia." (I guess I have typed
"Type Ia" a few too many times, and it has now become a semi-automatic reflex... :-(


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'