Mature looking galaxies 11.5 Gy ago

Le 18/09/13 08:29, Steve Willner a écrit :
In article ,
jacob navia writes:
Since the big bang supposes that *NOTHING* is older than 13.7 billion
years it suffices to find *ONE* galaxy older than that to disprove it.

Please let us know if you find one.

Well, that was the purpose of my article.
1) Any galaxy at 11.5 GY has only around 2GY age at most.
2) The time needed to create the disk of the spiral galaxy Milky way
is around 7GY. Supposing that the disk was thicker at that
time, etc, still, an age of 2 GY (8 revolutions) seems stretching
things VERY far. At most, 2GY would BARELY suffice for creating a
small spiral gaaxy. But we are looking at MATURE ellipticals, that
are MUCH older than spirals according to ANY textbook of astronomy.

But, according to the big bang theory, they are ALSO 2GY old!!!

This is a very simple argument, and it would be nice if you would
adress it.

It wouldn't disprove the Big
Bang, though; all it would say is that the parameters (probably
mostly the Hubble constant) have different values than we now think.


Of course! I agree with that. The Big Bang can't be disproved.
Ptolomeus epicycles can't be disproved either. We would need
several billions epicycles more but it would "work".

There is a point where messing around with the parameters becomes
increasingly complicated. How would you explain the discrepancy
between the supposed value and the actual value?

SW The article uses G and M20 as proxies for morphological
SW classification. They work fine for local galaxies but maybe not so
SW well for distant ones.

Mmm, you have now to justify this.

On the contrary, the authors have to justify that these statistics
work for the distant population.


Excuse me but the authors are speaking of galaxies, i.e. objects with
well known properties. Why would they be different just because they
are far away? Are stars affected by "distance"? Are far away stars
different than near stars?

Why would distance affect this well established classification?

Distance has nothing to do with it. What I think you are missing
(despite my having stated it earlier) is that the distant galaxy
population looks nothing like the local population.

No, precisely. The Hubble sequence is in place!

That is to say,
one can find individual distant galaxies that look much like local
ones except for being physically smaller. However, one also finds
vast numbers of distant irregular galaxies that have no (or at most
rare) counterparts in the local Universe.


Since the red shift SHIFTS light, we are seeing those galaxies in UV
and in UV galaxies look much more irregular. Besides, this study has
looked at a BIG sample of galaxies, arriving at opposite conclusions
than you.

Furthermore, the G and M20 statistics don't measure at all the same
thing as human galaxy classifiers. In other words, G and M20 don't
_measure_ Hubble type, but they _correlate_ with it in the local
Universe. What they measure in distant galaxies has yet to be
established so far as I can tell (though I may have missed some
relevant work).


Now, you suppose that the correlation breaks down with distance without
producing any justification for this!

WHY would those parameters break down with distance? What is your
physical supposition for that?

http://www.astro.caltech.edu/~george...i-MilkyWay.pdf
begin quote
In fact, based on the new G- dwarf metallicity distributions, our model
suggests that it took seven billion years to complete the formation of
the thin disk in the Sun's vicinity.

Why do you think the thin disk is relevant to the present discussion?

How long did it take to form the Milky Way's thick disk, which is
analogous to what one sees in distant galaxies?


In any case more than 8 turns! (2GY)

What is the minimum theoretical time to form a disklike structure?


Look, apparently galaxies grow by eating smaller ones. Our galaxy has
eaten several "recently" and their debris form arcs of stars in the sky.

Those mergers are extremely slow. For a small galaxy like the Sagitarius
Dwarf, the process takes like 1GY. Just to incoporate a small galaxy!

Imagine the time needed to form a galaxy from scratch, incoporating
smaller ones, building the disk, etc etc.

Now, at 2GY we find ELLIPTICALS, that are yet older! A merger of the
Milky Way with Andromeda will take like 8GY! It will start to merge
in 4GY when they will collide, then they will start an intrincate dance
that takes forever at those distances and sizes.

Yes, 11.5 GY the galaxies were smaller and closer but forming an
elliptical supposes several collisions between spirals to arrive there!

The spirals must form, then collide to become ellipticals. All that in
just 2GY?


Can you tell me an example of a structure after the "bang" that we do
not find in our local universe?

You might want to browse through images of an unbiased sample of
high-z galaxies. A suitable sample is described at
http://iopscience.iop.org/0067-0049/...s_200_1_9.html
but I'm still looking for the image set.


Excuse me but I think you have done a mistake. That reference is the
DATA of the telescope. There is no analysis of the data, it is just
presented to the scientists so they can do their analysis and use that
data.

That is what the scientists in the reference did!

In THEIR abstract they say that they used the GOODS survey, the
reference you cite!

As far as I can read your reference (maybe I am missing something of
course) this is a presentation of Hubble data, no analysis is done.

Thank you for your answer Mr Willner.

In article ,
I wrote:
You might want to browse through images of an unbiased sample of
high-z galaxies. A suitable sample is described at
http://iopscience.iop.org/0067-0049/...s_200_1_9.html
but I'm still looking for the image set.

Roger told me where the images are, but it's a bit complicated. The
object catalog (in ASCII) is with the paper, and you can download and
browse the catalog and select the galaxies you want to look at, for
example those in a specified redshift range. (Browsing will probably
be simpler if you have a Unix-based machine such as a Mac and know
how to use the tools.) Each galaxy has an 8-digit identifier. To
get its image, use
http://www.ugastro.berkeley.edu/~rgr...xx_info_bw.jpg
where xxxxxxxx is the galaxy identifier. If you have Unix, it won't
be hard to make a shell script to download multiple images (using
wget if you have it or or curl -O on a Mac.)

An example image with explanation is Fig 6 of the paper. The model
for each image is a single Sersic fit. Index n=1 corresponds to a
disk, n=4 to a deVaucouleurs profile of an elliptical. However, n is
not a reliable classifier in itself, even locally. (There are papers
discussing this.) When I was classifying, I found it most helpful to
look at the residual images, i.e., the observed image minus the
model.

Have fun!

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

In article , jacob navia
writes:

But we are looking at MATURE ellipticals, that
are MUCH older than spirals according to ANY textbook of astronomy.

That's probably at low redshift. It logically does not follow that at
high redshift ellipticals must be older than spirals.

There is a point where messing around with the parameters becomes
increasingly complicated. How would you explain the discrepancy
between the supposed value and the actual value?

But we haven't yet reached that point. Galaxy evolution is an active
field, because not all is known. If your best argument against the Big
Bang hinges on details of the evolution of galaxies which are only being
discovered now, that sounds rather unconvincing.

Look, apparently galaxies grow by eating smaller ones. Our galaxy has
eaten several "recently" and their debris form arcs of stars in the sky.

Those mergers are extremely slow. For a small galaxy like the Sagitarius
Dwarf, the process takes like 1GY. Just to incoporate a small galaxy!

Imagine the time needed to form a galaxy from scratch, incoporating
smaller ones, building the disk, etc etc.

Keep in mind that the universe was denser at high redshift.

Now, at 2GY we find ELLIPTICALS, that are yet older!

See above.

Le 18/09/13 22:37, Steve Willner a écrit :
In article ,
I wrote:
You might want to browse through images of an unbiased sample of
high-z galaxies. A suitable sample is described at
http://iopscience.iop.org/0067-0049/...s_200_1_9.html
but I'm still looking for the image set.

Roger told me where the images are, but it's a bit complicated. The
object catalog (in ASCII) is with the paper, and you can download and
browse the catalog and select the galaxies you want to look at, for
example those in a specified redshift range. (Browsing will probably
be simpler if you have a Unix-based machine such as a Mac and know
how to use the tools.) Each galaxy has an 8-digit identifier. To
get its image, use
http://www.ugastro.berkeley.edu/~rgr...xx_info_bw.jpg
where xxxxxxxx is the galaxy identifier. If you have Unix, it won't
be hard to make a shell script to download multiple images (using
wget if you have it or or curl -O on a Mac.)

An example image with explanation is Fig 6 of the paper. The model
for each image is a single Sersic fit. Index n=1 corresponds to a
disk, n=4 to a deVaucouleurs profile of an elliptical. However, n is
not a reliable classifier in itself, even locally. (There are papers
discussing this.) When I was classifying, I found it most helpful to
look at the residual images, i.e., the observed image minus the
model.

Have fun!


Mr Willner

With all due respect you are wrong.

In the first sentence of the abstract of article I cited, the authors
say that they used exactly the data set you are pointing me to.

Please read the article:
http://xxx.lanl.gov/pdf/1306.4980.pdf

Thanks

In article ,
jacob navia writes:
2) The time needed to create the disk of the spiral galaxy Milky way
is around 7GY.

This is the chemical abundance age of the Milky Way thin disk. It
does not say much about the necessary time for _any_ disk to form.

Excuse me but the authors are speaking of galaxies, i.e. objects with
well known properties. Why would they be different just because they
are far away?

As I keep repeating, observations show that the distant galaxy
population is not like the local one. I can think of several reasons
for that; no doubt you can as well.

The Hubble sequence is in place!

That's doubtful, to say the least. There are some distant galaxies
with morphologies similar to those of local galaxies, but that's not
at all the same thing as your claim.

Since the red shift SHIFTS light, we are seeing those galaxies in UV
and in UV galaxies look much more irregular.

The galaxy classification I'm writing about is done in B for local
galaxies and in I for z=1 galaxies. Those are the same rest
wavelengths.

Besides, this study has looked at a BIG sample of galaxies,
arriving at opposite conclusions than you.

I think you need to read the paper more carefully and also be aware
of other work that has been done. What the authors actually wrote is
that the "backbone of the Hubble Sequence" was in place. I have no
idea what they mean by that statement, but I think I understand the
work behind it and what paper does and does not actually show.

Now, you suppose that the correlation breaks down with distance without
producing any justification for this!

Please reread what I wrote earlier. If the population is different,
it is not at all clear what the correlations mean. I don't doubt
that distant galaxies exhibit a variety of morphological classes.

SW How long did it take to form the Milky Way's thick disk, which is
SW analogous to what one sees in distant galaxies?

In any case more than 8 turns! (2GY)

Why do you think that?

Look, apparently galaxies grow by eating smaller ones.

That's one way galaxies grow. Another is cold gas inflow, which is
probably much more important, especially in the early Universe.

Those mergers are extremely slow. For a small galaxy like the Sagitarius
Dwarf, the process takes like 1GY. Just to incoporate a small galaxy!

It depends on what you mean by "incorporate" and also on the
parameters of the merger, in particular how gas-rich it is. There
are lots of models; you might want to search out some of them.

Imagine the time needed to form a galaxy from scratch, incoporating
smaller ones, building the disk, etc etc.

I don't have to imagine it. As I say, there are models.

Excuse me but I think you have done a mistake. That reference is the
DATA of the telescope.

No mistake. You seem to believe things that simply are not true, and
I thought you might like to browse through the data for yourself.
Picking out and downloading the images could be a bit tedious if you
don't have good tools, but it is crucial to select an appropriate
sample. Once you've got the images, if you have a Mac, "Finder" has
a very nice tool for browsing through them. "Windows Preview" (I
think it's called) in MS-Windows is also good. I'm assuming that you
are familiar with local morphological classification, but if not,
you'll want to seek out the _Hubble Atlas of Galaxies_ or something
similar.

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

Le 21/09/13 10:20, Steve Willner a critic :

As I keep repeating, observations show that the distant galaxy
population is not like the local one. I can think of several reasons
for that; no doubt you can as well.


Mr Willner.

Yes, you keep repeating that, but repetition is not an argument actually.

I cite from the paper I introduced in my first post:

quote
We discuss the state of the assembly of the Hubble Sequence in the mix
of bright galaxies at redshift 1.4 z ≤ 2.5 with a large sample of
1,671 galaxies down to HAB ∼ 26, selected from the HST/ACS and WFC3
images of the GOODS–South field obtained as part of the GOODS and
CANDELS observations.
end quote

So, this paper uses the SAME data base you pointed me to: the GOODS
database. Their sample size (1,671 galaxies) is substantive.

Note that the authors pose the question why other studies showed
a galaxy population apparently more irregular than what they observed.

I cite again:

quote, page 2
Until relatively recently, most studies of galaxy morphologies at z 2
have been performed at rest–frame ultraviolet (UV) wavelengths using
optical imagers (such as HST/WFPC2 and HST/ACS). These works found that
irregular or peculiar structures appear more common, and traditional
Hubble types do not appear to be present at these epochs (Giavalisco et
al. 1996a,b; Steidel et al. 1996; Lowenthal et al. 1997; Lotz et al.
2004; Papovich et al. 2005; Lotz et al. 2006; Ravindranath et al. 2006;
Law et al. 2007; Conselice et al. 2008). This is generally explained as
due to the fact that UV radiation predominantly traces emission from the
star-forming regions (Dickinson 2000), which tend to be more clumped and
irregularly distributed than older stellar populations, and also by the
fact that quenched galaxies were missing from the optical images. The
rest-frame optical regime is a better probe of the overall stellar
distribution in galaxies, and early near–infrared (NIR) observations
with HST and NICMOS of star–forming galaxies at z 2 from UV selected
samples found that their morphology remains generally compact and
disturbed also at rest-frame optical wavelengths and bear no obvious
morphological similarities to lower redshift galaxies (Papovich et al.
2005; Conselice et al. 2008). Interestingly, however, Kriek et al.
(2009) showed that 19 spectroscopically confirmed massive galaxies (
1010.5M⊙) at z ∼ 2.3 are clearly separated into two classes as a blue
cloud with large star-forming galaxies, and a red sequence with compact
quiescent galaxies.
end quote

I can't go on citing "in extenso" all the article. Please read it and
refer to it pointing me what flaws you see in the methods followed by
those astronomers. Just repeating "observations show" is not really
an answer in a scientific discussion.

Thanks for your input Mr Willner.


------------

To the moderator:
Probably I have (again) some non-ascii characters in the cited text.
I apologize but there is no way to eliminate them in a Macintosh.
Sorry, and thanks for your work.

Le 21/09/13 10:20, Steve Willner a critic :

As I keep repeating, observations show that the distant galaxy
population is not like the local one. I can think of several reasons
for that; no doubt you can as well.


Mr Willner.

Yes, you keep repeating that, but repetition is not an argument actually.

I cite from the paper I introduced in my first post:

quote
We discuss the state of the assembly of the Hubble Sequence in the mix
of bright galaxies at redshift 1.4 z 2.5 with a large sample of
1,671 galaxies down to HAB ~ 26, selected from the HST/ACS and WFC3
images of the GOODS-South field obtained as part of the GOODS and
CANDELS observations.
end quote

So, this paper uses the SAME data base you pointed me to: the GOODS
database. Their sample size (1,671 galaxies) is substantive.

Note that the authors pose the question why other studies showed
a galaxy population apparently more irregular than what they observed.

I cite again:

quote, page 2
Until relatively recently, most studies of galaxy morphologies at z 2
have been performed at rest–frame ultraviolet (UV) wavelengths using
optical imagers (such as HST/WFPC2 and HST/ACS). These works found that
irregular or peculiar structures appear more common, and traditional
Hubble types do not appear to be present at these epochs (Giavalisco et
al. 1996a,b; Steidel et al. 1996; Lowenthal et al. 1997; Lotz et al.
2004; Papovich et al. 2005; Lotz et al. 2006; Ravindranath et al. 2006;
Law et al. 2007; Conselice et al. 2008). This is generally explained as
due to the fact that UV radiation predominantly traces emission from the
star-forming regions (Dickinson 2000), which tend to be more clumped and
irregularly distributed than older stellar populations, and also by the
fact that quenched galaxies were missing from the optical images. The
rest-frame optical regime is a better probe of the overall stellar
distribution in galaxies, and early near–infrared (NIR) observations
with HST and NICMOS of star-forming galaxies at z 2 from UV selected
samples found that their morphology remains generally compact and
disturbed also at rest-frame optical wavelengths and bear no obvious
morphological similarities to lower redshift galaxies (Papovich et al.
2005; Conselice et al. 2008). Interestingly, however, Kriek et al.
(2009) showed that 19 spectroscopically confirmed massive galaxies (
10^10.5M_solar) at z ~ 2.3 are clearly separated into two classes as a blue
cloud with large star-forming galaxies, and a red sequence with compact
quiescent galaxies.
end quote

I can't go on citing "in extenso" all the article. Please read it and
refer to it pointing me what flaws you see in the methods followed by
those astronomers. Just repeating "observations show" is not really
an answer in a scientific discussion.

Thanks for your input Mr Willner.

[Mod. note: non-ASCII characters removed. It is perfectly possible for
all users of the newsgroup to learn to recognise non-ASCII characters
and do this themselves -- mjh]

In article ,
jacob navia writes:
but repetition is not an argument actually.

Nor is it intended to be. I've described what observations show and
pointed to the source data. You are free to check my conclusions for
yourself. (Just be sure to define an unbiased sample to look at.)

I can't go on citing "in extenso" all the article. Please read it and
refer to it pointing me what flaws you see in the methods followed

The paper is nice work. My previous posts have described some of its
limitations -- I wouldn't call them flaws. Perhaps understanding the
issues requires more context of other work and other observations
than I was able to give.

I've heard that a large effort by human classifiers is about to be
published. It will be interesting to see what it shows.

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

The observations reported in
http://www.sciencedaily.com/releases...0815083953.htm
http://xxx.lanl.gov/pdf/1306.4980.pdf

report elliptical galaxies appearing 11.5 Gy ago.

Since ellipticals are around 7/8 Gy old, we have:

11.5 + 7 -- 18.5 Gy

The universe is at least 18.5 Gy old and not 13.7.

If we want to maintain big bang theory this means that the supposed bang
happened before, i.e. (rounding up), 20 Gy ago.

[Mod. note: spot the incorrect assumption -- mjh]

In article , jacob navia
writes:

The observations reported in
http://www.sciencedaily.com/releases...0815083953.htm
http://xxx.lanl.gov/pdf/1306.4980.pdf

report elliptical galaxies appearing 11.5 Gy ago.

Since ellipticals are around 7/8 Gy old, we have:

11.5 + 7 -- 18.5 Gy

The universe is at least 18.5 Gy old and not 13.7.

If we want to maintain big bang theory this means that the supposed bang
happened before, i.e. (rounding up), 20 Gy ago.

[Mod. note: spot the incorrect assumption -- mjh]

Easy. In fact, it is hard to believe that Jacob isn't playing devil's
advocate here. Yes, the typical age of a local elliptical galaxy might
be 7 or 8 Gy. But, obviously, a few Gy ago these were a few Gy
younger (duhhh!). Mr Navia seems to be assuming that "elliptical
galaxy" == "7--8 Gy old", no matter when it was observed. Obviously,
high-redshift galaxies are seen at a much younger age than they are now.