Surprisingly young galaxy found.

http://groups.google.com/group/sci.s...afc08c13a79b7#

I wonder if the "foreground lensing galaxy" has any "radial" kinetic
motion (other than expansion), and if that could skew the perceived
age of this young galaxy?

I seem to recall a paper that talked about "frame dragging" being able
to boost photons on one "side" of a spinning body, and retard photons
on the other...

David A. Smith

"dlzc" wrote in message
...
|
http://groups.google.com/group/sci.s...afc08c13a79b7#
|
| I wonder if the "foreground lensing galaxy" has any "radial" kinetic
| motion (other than expansion), and if that could skew the perceived
| age of this young galaxy?
|
| I seem to recall a paper that talked about "frame dragging" being able
| to boost photons on one "side" of a spinning body, and retard photons
| on the other...
|
| David A. Smith
|
"It could even help solve the mystery of how the hydrogen
fog that filled the early universe was cleared." said Johan
Richard of the Centre de Recherché Astronomique de Lyon,
Université Lyon 1 in France.

Not much need for a big bonk if the universe was filled
with hydrogen which clumps into stars under the force
of gravity, is there?
Such a universe could as easily be static, always was and
always will be.
In the beginning there was no beginning, forever and ever,
Amen.
You do drag up some drivel, Smiffy.

On 12/04/2011 4:45 PM, dlzc wrote:
http://groups.google.com/group/sci.s...afc08c13a79b7#

I wonder if the "foreground lensing galaxy" has any "radial" kinetic
motion (other than expansion), and if that could skew the perceived
age of this young galaxy?

I seem to recall a paper that talked about "frame dragging" being able
to boost photons on one "side" of a spinning body, and retard photons
on the other...

David A. Smith

Well, the velocity of the foreground galaxy would then be resolvable by
measuring its redshift. I think the assumption is that the bigger the
redshift, the bigger the distance. So whether the lensing galaxy is
distant galaxy with no radial velocity, or a relatively closer galaxy
with a large velocity away from us, the effect would be the same on the
lensed galaxy.

Yousuf Khan

Dear Yousuf Khan:

On Apr 12, 11:09*pm, Yousuf Khan wrote:
On 12/04/2011 4:45 PM, dlzc wrote:

snip link now broken by Google.Groups

I wonder if the "foreground lensing galaxy" has any
"radial" kinetic motion (other than expansion), and
if that could skew the perceived age of this young
galaxy?

I seem to recall a paper that talked about "frame
dragging" being able to boost photons on one "side"
of a spinning body, and retard photons on the other...

Well, the velocity of the foreground galaxy would then
be resolvable by measuring its redshift.

Yes, but the foreground galaxy was not identified.

I think the assumption is that the bigger the redshift,
the bigger the distance.

Right. So a lensing galaxy "kinetically" moving towards us might make
the image larger, but would uniformly redshift the light from the
distant galaxy. Making it appear older.

So whether the lensing galaxy is distant galaxy with
no radial velocity, or a relatively closer galaxy
with a large velocity away from us, the effect would be
the same on the lensed galaxy.

I don't think so. If it had the same kinetic motion wrt the Universe
*then* that we do *now*, there would be no effect. But I think there
would be if it had a significantly different motion. Now granted,
it'd have to be moving pretty significantly fast to affect the
observed z by much... which is unlikely.

David A. Smith

Try
http://groups.google.com/group/sci.s...c13a79b7?pli=1
for the press release,
http://lanl.arxiv.org/abs/1102.5092
for the preprint.

I've had only a quick look at the preprint, so it's quite possible
I've overlooked something or made a mistake, but here's what I
understand at the moment.

In article ,
dlzc writes:
I wonder if the "foreground lensing galaxy" has any "radial" kinetic
motion (other than expansion),

If you are asking about "peculiar velocity," no doubt it has some but
probably not much. Clusters are massive objects and can't easily be
perturbed from the overall Hubble flow.

and if that could skew the perceived age of this young galaxy?

Why would you expect motion of the lens to affect the age estimate?
The redshift of the object was measured directly (albeit with only a
single line plus the photometry), and the stellar population age
inference comes from the spectral energy distribution, in particular
the Balmer break. Neither of these would be affected by anything
having to do with the lens.

What would be affected, if the lensing model is wrong, are the
luminosity and estimated stellar mass of the high-z galaxy. However,
the model was based on observed cluster galaxies (The lensing cluster
is A383, a well-known cluster.) and validated by four lensed sources
as well as the two images of the high-redshift galaxy itself, so the
lensing model is probably not too bad.

Things that could affect the age estimate are the exact star
formation history and dust reddening. In particular, according to
the authors, the best-fit range using their stellar templates is 640
to 940 Myr, and different assumptions could give an even younger age
(though the authors claim it won't fit all the data).

I seem to recall a paper that talked about "frame dragging" being able
to boost photons on one "side" of a spinning body, and retard photons
on the other...

Sounds like that would need relativistic speeds to have much effect.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA