Superluminal Quasar Jets : The Beaming "Explanation" Appears Inadequate

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox ha scritto nel
messaggio news:QosTd.81173$Yu.50458@fed1read01...
Dear Luigi Caselli:

"Luigi Caselli" wrote in message
...

According to Einstein, nothing can be faster than light speed inside our
universe...
So superluminal motions must be only optical illusion...
Otherwise you must create a new theory and throw away relativity.

... which some consider desirable.

Yes, for example Star Trek fans hate this kind of silly speed limit...

But they must also throw away Maxwell, since he allows light to leave
these
"superlumenal" event.

Too many things to throw away...

Luigi Caselli

Dear Martin Brown:

"Martin Brown" wrote in message
...
N:dlzc D:aol T:com (dlzc) wrote:
....
The conventional explanantion for the superluminal motions observed in
many quasar-type jets is that it is an optical illusion due to the jets
being oriented at a fairly narrow angle to our line of sight.

And it is a very good explanation that fits the observations nicely.
...

If the jets are truly superlumenal, how is it that we can see light from
them? Since we *do* see light from them, and their spectra are
"reasonable", the rest is "tricks of geometry". If they were
superlumenal, the light could never leave...

Not quite. Provided that the beam is pointing roughly towards us and/or
not receding faster than the speed of light we can still see it easily.
If a truly superluminal jet were pointed at us the material in the jet
would arrive marginally before

We are going to pick nits here, I guess. At 6c, without "Cerenkov braking"
(my apologies to purists), "marginally before" would be 5000 years before,
for a 6000 year trip at c.

Classical Cerenkov radiation involves a medium and a moving charge.
Uncharged matter would theoretically not be subject to Cerenkov radiation
(I don't know if neutron streams are faster than c/1.4, but it would be
hard to separate them from the other particles in the mix that *are*
charged).

the light emitted from it (assuming that it continued to emit light and
stayed superluminal all the way).

And the intensity and spectrum received would be... blueshifted beyond
what? Gamma, cosmic, what? Light could not leave the surface of the face
coming at us, if it were superlumenal. 1/2 wavelength out, and the
emitting object "crashes" into the photon stream.

But even if it were truly receding faster than the speed of light we
would still see the turbulent backwash it created in the intergalactic
medium. The high resolution 5GHz image of the radio galaxy Cygnus A shows
one relativistic jet very clearly most of the way out into the lobe.

But by far the simplest explanation of apparent superluminal motion in
quasar jets is that it is a purely geometrical line of sight effect of
beaming with standard relativistic physics.

Absolutely correct.

David A. Smith

If anyone wants background on this problem, here is a very
good, concise article from astrophysical journal. It includes
fascinating pix of the "superluminal" features over time, too:

http://www.journals.uchicago.edu/ApJ...787/39787.html

=[ d

DavidBowman wrote:
If anyone wants background on this problem, here is a very
good, concise article from astrophysical journal. It includes
fascinating pix of the "superluminal" features over time, too:

http://www.journals.uchicago.edu/ApJ...787/39787.html


Thanks David.
-Sam

N:dlzc D:aol T:com (dlzc) wrote:
Dear Chris O'Riordan:

"Chris O'Riordan" wrote in message
oups.com...
The conventional explanantion for the superluminal motions observed
in
many quasar-type jets is that it is an optical illusion due to the
jets
being oriented at a fairly narrow angle to our line of sight.
...

If the jets are truly superlumenal, how is it that we can see light
from
them? Since we *do* see light from them, and their spectra are
"reasonable", the rest is "tricks of geometry". If they were
superlumenal,
the light could never leave...

David A. Smith

I had in mind a VSL (variable light speed) possible explanation, where
the jet knots would not exceed the *local* value of c. The latter
would need to be ~3 X 10^9 m/s at least in the case of quasar 3C273,
for example.

This is just a speculation, of course. I don't know why c would
increase significantly outward along the axis of a (rotating,
supermassive) black hole. Something to do with twizzled-up spacetime,
mayhap?!

Martin Brown wrote:
N:dlzc D:aol T:com (dlzc) wrote:

Dear Chris O'Riordan:

"Chris O'Riordan" wrote in message
oups.com...

The conventional explanantion for the superluminal motions observed
in
many quasar-type jets is that it is an optical illusion due to the
jets
being oriented at a fairly narrow angle to our line of sight.

And it is a very good explanation that fits the observations nicely.


There are key cases where it emphatically DOESN'T appear to fit, as I
mentioned in
http://www.geocities.com/chrisori2000/superjet.htm

To recap:-

(For the 7 known superluminals in 1983,) the structures did NOT in
general appear to be oriented close to the line-of-sight;

Mackay, Thompson et al suggested in 1993 that the (outer) jet of quasar
3C273 was nearly PERPENDICULAR, rather than nearly parallel, to the
line-of-sight. Superluminal motion of up to ~9.6c has been observed
along the (inner) jet;

The jet of the galaxy M87 needs to be at ~19 degrees to the
line-of-sight to explain by beaming superluminal motion of up to ~6c in
it -- but independent evidence on the jet's orientation suggests it is
at ~43 degrees to our line-of-sight.

"CO" == Chris O'Riordan writes:

CO There are key cases where it emphatically DOESN'T appear to fit,
CO as I mentioned in
CO http://www.geocities.com/chrisori2000/superjet.htm

There appears to be some link rot here.

CO To recap:-

CO (For the 7 known superluminals in 1983,) the structures did NOT in
CO general appear to be oriented close to the line-of-sight;

CO Mackay, Thompson et al suggested in 1993 that the (outer) jet of
CO quasar 3C273 was nearly PERPENDICULAR, rather than nearly
CO parallel, to the line-of-sight. Superluminal motion of up to
CO ~9.6c has been observed along the (inner) jet;

I can find no paper in ADS with the authors "Mackay" and "Thompson."
Perhaps you could post a reference?

CO The jet of the galaxy M87 needs to be at ~19 degrees to the
CO line-of-sight to explain by beaming superluminal motion of up to
CO ~6c in it -- but independent evidence on the jet's orientation
CO suggests it is at ~43 degrees to our line-of-sight.

Doesn't this require independent knowledge of the speed of the ejecta?
Reference?

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"NDT" == N:dlzc D:aol T:com \(dlzc\) N writes:

NDT My point was, if they are moving towards us in any sense, faster
NDT than c, then the particle/body/object will outrun the light. We
NDT could *see* nothing coming towards us. And the faster it is,
NDT the closer it would have to be to "motion at 90 deg to line of
NDT sight" to keep from outrunning light that leaves towards us.

Yes, but the model isn't that the ejecta is moving faster than the
speed of light. Consider ejecta moving at 0.999c and moving toward
you.

--
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Dear Joseph Lazio:

"Joseph Lazio" wrote in message
...
"NDT" == N:dlzc D:aol T:com \(dlzc\) N writes:

NDT My point was, if they are moving towards us in any sense, faster
NDT than c, then the particle/body/object will outrun the light. We
NDT could *see* nothing coming towards us. And the faster it is,
NDT the closer it would have to be to "motion at 90 deg to line of
NDT sight" to keep from outrunning light that leaves towards us.

Yes, but the model isn't that the ejecta is moving faster than the
speed of light. Consider ejecta moving at 0.999c and moving toward
you.

The concern appears to be "what if they are superlumenal". The standard
model doesn't have the problem I described. He has so far ignored the
"normal spectrum", which also limits the jet to sublumenal speed.

Maxwell provides the conundrum I describe, since light travels at c for all
observers, yet light leaves "forward" from an object travelling at c. He
seems to be running towards Fizeau next...

David A. Smith

N:dlzc D:aol T:com (dlzc) wrote:
Dear Joseph Lazio:

"Joseph Lazio" wrote in message
...
"NDT" == N:dlzc D:aol T:com \(dlzc\) N writes:

NDT My point was, if they are moving towards us in any sense,
faster
NDT than c, then the particle/body/object will outrun the light.
We
NDT could *see* nothing coming towards us. And the faster it is,
NDT the closer it would have to be to "motion at 90 deg to line of
NDT sight" to keep from outrunning light that leaves towards us.

Yes, but the model isn't that the ejecta is moving faster than the
speed of light. Consider ejecta moving at 0.999c and moving toward
you.

The concern appears to be "what if they are superlumenal". The
standard
model doesn't have the problem I described. He has so far ignored
the
"normal spectrum", which also limits the jet to sublumenal speed.

Maxwell provides the conundrum I describe, since light travels at c
for all
observers, yet light leaves "forward" from an object travelling at c.
He
seems to be running towards Fizeau next...

Then wasn't Maxwell saying c'=c+v , and thus in direct conflict with
AE?

How is the increasing length per time (velocity) of these jets
measured?
SR believers might claim that the only legitimate measurement would be
that of a traveller on the jet! Otherwise, SR is decapitated right
here, with the obvious and trivial observation that velocity has NOT
shrunken the moving body!

Jim G
c'=c+v