Doppler Tests on Local Stars

Thus spake Joseph Lazio
"ON" == Oh No writes:

ON It is probable others understand a lot more about VLBI than I
ON do. When the position of SgrA* is measured do they have to take
ON into account gravitational red shift of light emanating from the
ON centre of the galaxy? Of course this would not affect distant
ON quasars.

No, for two reasons. First, the VLBI observations of Sgr A* are
continuum measurements. They observe at 43 GHz with several 8-MHz
bandwidths, processing everything within each 8-MHz bandwidth. For
the sake of illustration, suppose that one of these bands is 43.0 GHz
to 43.008 GHz. Pick your favorite value for the expected redshift, z,
from the environment of Sgr A*. Provided that Sgr A* emits between
43.0*(1+z) and 43.008*(1+z), their analysis is unchanged. Given that
Sgr A* is seen at frequencies much higher than 43 GHz, ignoring z in
this case is not a problem.

I do not understand this. As I understand the paper, they use a distant
quasar as a reference. The signal from the distant quasar will not be
subjected to gravitational redshift from the centre of the galaxy,
whereas the signal from SgrA* will.

Second, assuming that general relativity is correct (or approximately
so), the radiation we see as Sgr A* of course does not come from the
black hole itself but its environment.

That is not important. For example the Pound Rebka experiment measured
the gravitational redshift of a source in the environment of the Earth.
There will be a redshift corresponding to the change in gravitational PE
of an object coming from near the centre of the galaxy.

I'm not sure we know the
actual distance, but my vague recollection is that it must be several
tens if not a few hundred gravitational radii away from the hole.
Without plugging in the numbers, I suspect that the gravitational
redshift at several tens of gravitational radii from a black hole is
not all that large.

I do not think one would need a large shift to get a noticeable change
in an interference pattern. Without the numbers I don't think any
conclusion can be drawn.

ON In the standard model the contained mass in a given radius, r,
ON including CDM, should be roughly given by

ON v^2/r = GM/r^2

ON For a rotation speed of ~235km/s at 8kpc, as determined by Reid
ON and Brunthaler, I think that gives a contained mass of a little
ON over 100Bill Suns. What would the effect on the VLBI calculation
ON of orbital motion be if there were only 55 Bill solar masses
ON within that radius?

Note that the VLBI calculation is the reverse. The measured quantity
is (v/r). There are a variety of estimates for r, but 8 kpc is a
reasonable value. In order to obtain your value of M, they would have
had to have made a serious error in their analysis.

The hypothesised error is in v, not in r. In order to obtain the numbers
I have obtained for the correlations between radial and transverse
velocities there has to be a systematic error in radial velocity. From
those tests it is not possible to precisely quantify the error, but in
the case of halo stars within 500pc, a systematic 20% error is not
sufficient to explain the result. For type A main sequence stars within
200pc a systematic 10% error is not sufficient to explain it. I do not
believe that a systematic error on this scale could be put down a fault
in measurement procedures on local stars.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Thus spake Joseph Lazio
"ON" == Oh No writes:

ON Thus spake Steve Willner

Quasar positions measured by VLBI agree with those measured by
classical astrometry.

ON Yes, but in quantum theory when you do a classical measurement the
ON wave function collapses. There is a discontinuity in the
ON description of motion at the time of measurement. I am also
ON expecting a discontinuity in VLBI measurements when carried out
ON over a sufficient time that classical astronometry becomes
ON possible. Whether the apparent discontinuity in motion of IM
ON Pegasi is an instance of that, I would not like to say.

You'll have to define your terms quantitatively. Brisken et
al. (2003, AJ, 126, 3090) report observations of pulsars over a
minimum time baseline of 7 years. At least one pulsar (B1237+25) has
a proper motion in excess of 0.1 arcsec/year; over the course of their
observations it moved a distance of about 0.8 arcseconds.

Does 7 years and 0.8 arcseconds qualify as sufficient for "classical"
astrometry? If not, what does?

Of course it does, but this is another change of subject. Pulsars are a
high velocity star population and of little value or relevance in
measurements the orbital motion of the galaxy.



Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Oh No wrote:
Thus spake Joseph Lazio

Does 7 years and 0.8 arcseconds qualify as
sufficient for "classical" astrometry? If not,
what does?

Of course it does, but this is another change of
subject. Pulsars are a high velocity star
population and of little value or relevance in
measurements the orbital motion of the galaxy.

Huh? Many pulsars are still part of the binary
partner stars with which they began their existence.

There is no reason to believe that such stars would
have motions different in kind from the rest of
stars in the the galaxy with which they rotate.

Moreover, pulsars are excellent tools for exactly
the kind of measurements you're attempting to
evaluate:

"Physical parameters accessible through
pulsar timing include the three-dimensional
position of the pulsar, its proper motion,
the electron content of the interstellar
medium along the propagation path, the
orbital parameters of any binary companion,
the pulsar rotation period and its evolution
with time."

http://en.wikipedia.org/wiki/Pulsar

Once again you seem to be insistently dismissing any
evidence that contradicts your thesis, as
"irrelevant". That approach isn't going to win you
any converts.

Quantum valeat.

xanthian.

"ON" == Oh No writes:

ON Thus spake Joseph Lazio

ON It is probable others understand a lot more about VLBI than I
ON do. When the position of SgrA* is measured do they have to take
ON into account gravitational red shift of light emanating from the
ON centre of the galaxy? Of course this would not affect distant
ON quasars.

No, for two reasons. First, the VLBI observations of Sgr A* are
continuum measurements. They observe at 43 GHz with several 8-MHz
bandwidths, processing everything within each 8-MHz bandwidth. For
the sake of illustration, suppose that one of these bands is 43.0
GHz to 43.008 GHz. Pick your favorite value for the expected
redshift, z, from the environment of Sgr A*. Provided that Sgr A*
emits between 43.0*(1+z) and 43.008*(1+z), their analysis is
unchanged. Given that Sgr A* is seen at frequencies much higher
than 43 GHz, ignoring z in this case is not a problem.

ON I do not understand this. As I understand the paper, they use a
ON distant quasar as a reference. The signal from the distant quasar
ON will not be subjected to gravitational redshift from the centre of
ON the galaxy, whereas the signal from SgrA* will.

Yes, but that's irrelvant from the VLBI standpoint. The only question
as far as VLBI is concerned is, Do we receive radiation from both
objects at 43 GHz?

[...]
I'm not sure we know the [size of the radio-emitting region], but
my vague recollection is that it must be several tens if not a few
hundred gravitational radii away from the hole. Without plugging
in the numbers, I suspect that the gravitational redshift at
several tens of gravitational radii from a black hole is not all
that large.

ON I do not think one would need a large shift to get a noticeable
ON change in an interference pattern.

All of the light from Sgr A* would be affected the same amount. There
would be no change in the interference pattern.



ON In the standard model the contained mass in a given radius, r,
ON including CDM, should be roughly given by

ON v^2/r = GM/r^2

ON For a rotation speed of ~235km/s at 8kpc, as determined by Reid
ON and Brunthaler, I think that gives a contained mass of a little
ON over 100Bill Suns. What would the effect on the VLBI calculation
ON of orbital motion be if there were only 55 Bill solar masses
ON within that radius?

Note that the VLBI calculation is the reverse. The measured
quantity is (v/r). There are a variety of estimates for r, but 8
kpc is a reasonable value. In order to obtain your value of M,
they would have had to have made a serious error in their analysis.

ON The hypothesised error is in v, not in r.

Which I don't see how you obtain. Again, (v/r) is the measured
quantity. We think we know r. That gives us v.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

"ON" == Oh No writes:

ON Thus spake Joseph Lazio
"ON" == Oh No writes:

ON Thus spake Steve Willner

Quasar positions measured by VLBI agree with those measured by
classical astrometry.

ON Yes, but in quantum theory when you do a classical measurement the
ON wave function collapses. There is a discontinuity in the
ON description of motion at the time of measurement. I am also
ON expecting a discontinuity in VLBI measurements when carried out
ON over a sufficient time that classical astronometry becomes
ON possible. Whether the apparent discontinuity in motion of IM
ON Pegasi is an instance of that, I would not like to say.

You'll have to define your terms quantitatively. Brisken et
al. (2003, AJ, 126, 3090) report observations of pulsars over a
minimum time baseline of 7 years. At least one pulsar (B1237+25)
has a proper motion in excess of 0.1 arcsec/year; over the course
of their observations it moved a distance of about 0.8 arcseconds.

Does 7 years and 0.8 arcseconds qualify as sufficient for
"classical" astrometry? If not, what does?

ON Of course it does, but this is another change of subject. Pulsars
ON are a high velocity star population and of little value or
ON relevance in measurements the orbital motion of the galaxy.

I'll restate my question: You'll have to define your terms
quantitatively. Astrometry at radio wavelengths using interferometers
has been done over the angular and time scales of "classical"
astrometry.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

Thus spake Joseph Lazio
"ON" == Oh No writes:

ON I do not think one would need a large shift to get a noticeable
ON change in an interference pattern.

All of the light from Sgr A* would be affected the same amount. There
would be no change in the interference pattern.

As I understand they are measuring interferance between light from two
different sources. If one is shifted, there certainly will be a change
in interference pattern.

ON In the standard model the contained mass in a given radius, r,
ON including CDM, should be roughly given by

ON v^2/r = GM/r^2

ON For a rotation speed of ~235km/s at 8kpc, as determined by Reid
ON and Brunthaler, I think that gives a contained mass of a little
ON over 100Bill Suns. What would the effect on the VLBI calculation
ON of orbital motion be if there were only 55 Bill solar masses
ON within that radius?

Note that the VLBI calculation is the reverse. The measured
quantity is (v/r). There are a variety of estimates for r, but 8
kpc is a reasonable value. In order to obtain your value of M,
they would have had to have made a serious error in their analysis.

ON The hypothesised error is in v, not in r.

Which I don't see how you obtain. Again, (v/r) is the measured
quantity. We think we know r. That gives us v.

v/r is not directly measured. It is determined on the basis of the
assumption that we know the relationship between frequencies and v/r
from classical physics. I am working in a model in which that
relationship is changed. In those cases where I have been able to
analyse how that relationship is changed, I have produced results
consistent with observation where the standard model either can't
produce or can't explain results consistent with observation. In the
case of VLBI from SgrA*, I still have no analysis. The absence of
analysis is not proof of inconsistency.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Thus spake Kent Paul Dolan
Oh No wrote:
Thus spake Joseph Lazio

Does 7 years and 0.8 arcseconds qualify as
sufficient for "classical" astrometry? If not,
what does?

Of course it does, but this is another change of
subject. Pulsars are a high velocity star
population and of little value or relevance in
measurements the orbital motion of the galaxy.

Huh? Many pulsars are still part of the binary
partner stars with which they began their existence.

There is no reason to believe that such stars would
have motions different in kind from the rest of
stars in the the galaxy with which they rotate.

I am not suggesting that they do, excepting in so far as that they are a
high velocity population. We do not determine the orbital motion of the
galaxy from such stars. We do determine it from globular clusters, from
open clusters, and now from VLBI measurements on SgrA*, with,
incidentally, inconsistent results.

Moreover, pulsars are excellent tools for exactly
the kind of measurements you're attempting to
evaluate:

"Physical parameters accessible through
pulsar timing include the three-dimensional
position of the pulsar, its proper motion,
the electron content of the interstellar
medium along the propagation path, the
orbital parameters of any binary companion,
the pulsar rotation period and its evolution
with time."

http://en.wikipedia.org/wiki/Pulsar

Unfortunately the link to the catalogue of pulsars cited there was
broken. However I will look into them.

Once again you seem to be insistently dismissing any
evidence that contradicts your thesis, as
"irrelevant". That approach isn't going to win you
any converts.

Once again you are talking rot. How are pulsars supposed to contradict
my thesis. All I have said is that from what I know of them they will
not form a suitable database for the type of test I have run. You, on
the other hand, knowing nothing about the test, are prepared to
pronounce. You are even prepared to fabricate ridiculous claims about
how the orbital motion of the galaxy is measured. I think you should
learn some astrophysics first.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Thus spake Joseph Lazio
"ON" == Oh No writes:

ON Thus spake Joseph Lazio
"ON" == Oh No writes:

ON Thus spake Steve Willner

Quasar positions measured by VLBI agree with those measured by
classical astrometry.

ON Yes, but in quantum theory when you do a classical measurement the
ON wave function collapses. There is a discontinuity in the
ON description of motion at the time of measurement. I am also
ON expecting a discontinuity in VLBI measurements when carried out
ON over a sufficient time that classical astronometry becomes
ON possible. Whether the apparent discontinuity in motion of IM
ON Pegasi is an instance of that, I would not like to say.

You'll have to define your terms quantitatively. Brisken et
al. (2003, AJ, 126, 3090) report observations of pulsars over a
minimum time baseline of 7 years. At least one pulsar (B1237+25)
has a proper motion in excess of 0.1 arcsec/year; over the course
of their observations it moved a distance of about 0.8 arcseconds.

Does 7 years and 0.8 arcseconds qualify as sufficient for
"classical" astrometry? If not, what does?

ON Of course it does, but this is another change of subject. Pulsars
ON are a high velocity star population and of little value or
ON relevance in measurements the orbital motion of the galaxy.

I'll restate my question: You'll have to define your terms
quantitatively. Astrometry at radio wavelengths using interferometers
has been done over the angular and time scales of "classical"
astrometry.

That is not a question, and I cannot see what it is intended to imply,
or why you think it relevant to anything I have said. The proper motion
of pulsars does not have a bearing on the rotation rate of the galaxy.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Oh No wrote:

excepting in so far as that [pulsars] are a
high velocity population.

Once again you are talking rot.

Who is? Once again you have made your
unsubstantiated dismissive claim that pulsars are a
"high velocity population", which makes exactly zero
sense. There are a very few "jet driven" pulsars;
eliminate them by insisting on pulsars (easily
identified) in binary star pairs. Pulsars are just
collapsed stars, for the most part still orbiting
with their binary companions, having no reason to be
different in velocity compared to galactic radial
location than any other stars in the galaxy, still
in concept carrying their "group birth velocity",
while offering a wealth of measurement addenda to
the simple measurement of red-shift of each (binary
bound) pulsar's binary companion.

When you dismiss such obvious tools for checking
your theories because you find the facts about them
inconvenient (say, denying your theories), you are
playing fast and loose with intellectual dishonesty.

You may expect that your theories will somehow be
magically accepted despite the falsifying instances,
but having spent a _lot_ of my life helping
scientists do science, I would not have any such
expectation for your ideas gaining acceptance.

xanthian, typically listed under "thanks also to".

In article ,
Oh No wrote:
As I understand they are measuring interferance between light from two
different sources. If one is shifted, there certainly will be a change
in interference pattern.

You understand incorrectly. Effectively, they are measuring the
positions of several different objects using interference of light
that has followed multiple paths *from the same object*.

Gravitational redshift cannot produce the effect you need (which,
remember, is a systematic change in apparent angular speed in a
particular direction on the sky with respect to background sources).
It's easy to see that gravitational redshift is important on scales
much less than any interesting scale of the system, and of course it
is not going to have a directional effect on apparent motion on the
sky.

v/r is not directly measured. It is determined on the basis of the
assumption that we know the relationship between frequencies and v/r
from classical physics.

The point is here that we have an entirely different way of measuring
v/r. It agrees far better with the standard model than it does with
your model. You need to explain that agreement if you want your model
to be taken seriously. To do that you will need to understand the way
the observations are made.

Martin
--
Martin Hardcastle
School of Physics, Astronomy and Mathematics, University of Hertfordshire, UK
Please replace the xxx.xxx.xxx in the header with herts.ac.uk to mail me