More trouble for big bang theory

On Nov 3, 3:43*pm, Steve Willner wrote:

There's a big difference between "a surprise" on the one hand and
"incompatible" on the other. *As Thomas mentioned, the timescale for
one generation of stars is 10-100 Myr, so there's plenty of time for
enrichment, especially if the IMF is top-heavy.
-----------------------------------------------------------------------------

The discussion at one science site [ScienceDaily] says that the
observed metal abundances in such early galaxies "was unhinkable until
recently".

Clearly there is much confusion over the issue of metal abundances in
early galaxies.

In my 11/3 post I asked for a "line in the sand" regarding this issue.
But so far no response.

So I repeat my request: At what z value does moderate to high metal
abundance become exceedingly problematic for standard cosmology?

Surely, the standard model cannot accommodate all results, since that
would indicate unfalsifiability.

RLO
Fractal Cosmology

Robert L. Oldershaw asked:
At what z value does moderate to high metal
abundance become exceedingly problematic for standard cosmology?

I don't see any way to get "moderate to high" metal abundances,
or even "significant" ones (say 1% of solar) by redshift 1000
(that's ~ 350K years after the big bang), i.e., just after photons
decoupled from matter.

[It's likely that a careful analysis of population-III star formation
and nucleosynthesis would draw this "line in the sand" at a significantly
lower redshift, but "just after decompling" seems like a (conservative)
point to draw it.]

--
-- "Jonathan Thornburg [remove -animal to reply]"
Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA
"Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral."
-- quote by Freire / poster by Oxfam

In article ,
Jonathan Thornburg [remove -animal to reply] wrote:
Robert L. Oldershaw asked:
At what z value does moderate to high metal
abundance become exceedingly problematic for standard cosmology?

I don't see any way to get "moderate to high" metal abundances,
or even "significant" ones (say 1% of solar) by redshift 1000
(that's ~ 350K years after the big bang), i.e., just after photons
decoupled from matter.

..... of course, we don't expect to see any galaxies at those redshifts
in which to measure high metal abundances, either!

[It's likely that a careful analysis of population-III star formation
and nucleosynthesis would draw this "line in the sand" at a significantly
lower redshift, but "just after decompling" seems like a (conservative)
point to draw it.]

I just spent a few minutes on ADS, out of curiosity and because the
alternative is writing problems sheets about Fourier series, and found
various widely cited modelling papers (e.g. Yoshida et al 2003 ApJ 592
645) suggesting that significant star formation gets under way at 20
z 30 (i.e. roughly 100-200 Myr after the big bang). Again, this
gives a prediction that we wouldn't see galaxies much older than this,
but it also gives a less conservative line in the sand (less
conservative in the sense that it depends on complicated modelling and
not on the simple physics of the early universe).

Once star formation has started, though, and particularly if people
modelling these things are correct in believing that the first
generation of stars were very massive, then it's pretty clearly
possible to get very high abundances *in particular locations* very
quickly, at the end of the lives of the first stars, a few tens of Myr
after they formed (particularly if metal distribution is assisted by
the pair-instability supernova mechanism: e.g. Bromm & Larson 2004
ARA&A 42 79) and therefore to do so very comfortably by z ~ 10, 500
Myr after the BB. As Steve Willner pointed out, this is all you need
to do, since nobody has figured out a way of measuring meaningful
whole-galaxy elemental abundances even in the local universe.

I would be very interested if anyone can provide a widely cited
reference in a reputable journal using a vaguely modern cosmological
model that claims, as a couple of people have suggested in this
thread, that high metal abundances should never be observed at
redshifts lower than this (as opposed to claiming that the average
abundance should be low, which is true but uninteresting in this
context).

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

Le 04/11/11 07:03, eric gisse a écrit :
Steve wrote in
:

In ,
jacob writes:
"metal" rich galaxies incompatible with any bing bang
that would have happened only 1.7 billion years earlier.

http://www.eso.org/public/archives/r...s/eso1143/eso1
143.pdf

There's a big difference between "a surprise" on the one hand and
"incompatible" on the other. As Thomas mentioned, the timescale for
one generation of stars is 10-100 Myr, so there's plenty of time for
enrichment, especially if the IMF is top-heavy.

Its' gotta be.

Sure, if not, BB is doomed Oh catastrophe :-)

What happened?

We are looking essentially at a random sample of galaxies 12 billion
years ago. At that time a quasar happened to exist that pointed
exactly in the direction where 12 billion years later a star would
pass, that had a small rocky planet that happened to have the right
position at the end of northern summer so that the light of that
quasar hits the CCD of the VLT after all those billion years of journey.

There are SO many factors that happen to collaborate in making that
CCD point to that quasar (not only astronomical but also political,
the EU decided many years ago to build that VLT, those humans decided
to study astronomy etc) that it s essentially random.

And we hit two galaxies very rich in heavy elements. Just like that.

If we assume that having more heavy elements than our own sun would be
NORMAL for galaxies 12 billion years ago then ALL galaxies NOW should
have even MORE heavy elements since those elements do not go away but
accumulate with time. What would be extraordinary would be to find
heavy elements poor galaxies!!!

But they exist those metal poor galaxies not THAT far away from my
home. For instance I Zw 018, (UGCA 166) at only 20.98 Mpc.

Why?

If already 12 billion years ago a random sample of two galaxies
has more heavy elements than our own sun why hasn't this galaxy gotten
more of that?

Well, it is interesting to quote the scientific context as cited in

http://ned.ipac.caltech.edu/level5/Kunth/frames.html

quote
The age of IZw18 has been debated ever since the early seventies when
the intriguing properties of this galaxy were first realised. Being the
most metal-poor galaxy, it is of course one of the most promising
candidates for a genuinely young galaxy.
end quote

So, here we have a citation for an astronomer that believes that
metal poor galaxies must be young and metal rich galaxies old.

Normal.

But apparently I Zw 018 is not that young, maybe even 5Gyr old according
to the same article. In any case if most galaxies were metal rich 12
Gyrs ago it shouldn't exist.

Another metal poor galaxy is SBS0335-052, at 3.7 to 3.9 Mpc. I quote
again the same reference:

quote
This galaxy was found in the Second Byurakan Survey (SBS, Markarian and
Stepanian 1983). A number of papers from 1990 and onwards have shown it
to be a galaxy with an oxygen abundance comparable to that of IZw18
(Izotov et al. 1990, 1997b; Melnick et al. 1992). Melnick et al. (1992)
and Izotov et al. (1997b) both find an oxygen abundance of 1/40 of the
solar value.
[snip]
There have been several claims that this galaxy is a truly young galaxy,
not containing any underlying old population, (Thuan et al. 1997, Izotov
et al. 1997b, Papaderos et al. 1998). The argument put forward is the
low metallicity and the lack of any underlying population in surface
photometric data.
end quote

Here again we have the association of low metallicity with young
galaxies.

So, it is not that fair to say now that there is no association of
low "metallicity" (what a terminology) and age of a galaxy.

Since all galaxies at 12 billion years are very young (less than
1Gy) it would be normal that a stupid layman like me would assume
that a high metallicity would be a surprise.

The article I quoted says:

quote
The column density NZn II = 1013.57±0.04 cm−2 in G1 is also among the
highest ever inferred, with other systems of comparable density all
residing at z 2.9. The large column densities in G1 would indicate the
galaxy to be massive and/or metal rich. At this high redshift, this
would make G1 a rare object.
end quote

"A RARE OBJECT" indeed. In a scientific paper you just do not use words
like "unthinkable" as in the press release. But it is THE SAME of
course.

All other comparable systems reside at z 2.9. The two galaxies
observed are at z 3.57.

On Nov 4, 4:10*pm, "Jonathan Thornburg [remove -animal to reply]"
wrote:
Robert L. Oldershaw asked:

At what z value does moderate to high metal
abundance become exceedingly problematic for standard cosmology?

I don't see any way to get "moderate to high" metal abundances,
or even "significant" ones (say 1% of solar) by redshift 1000
(that's ~ 350K years after the big bang), i.e., just after photons
decoupled from matter.

[It's likely that a careful analysis of population-III star formation
and nucleosynthesis would draw this "line in the sand" at a significantly
lower redshift, but "just after decompling" seems like a (conservative)
point to draw it.]
------------------------------------------------------------------------------

Next question:

What is the largest z at which we can reliably observe actual physical
objects?

Do we still have falsifiability in this issue if the most distant
object so far observed is at z = 8 and we have to look back to z =
1000 to do the test?

RLO
Occupy Theoretical Physics

On Nov 4, 5:12*pm, Martin Hardcastle
wrote:

I just spent a few minutes on ADS, out of curiosity and because the
alternative is writing problems sheets about Fourier series, and found
various widely cited modelling papers (e.g. Yoshida et al 2003 ApJ 592
645) suggesting that significant star formation gets under way at 20
z 30 (i.e. roughly 100-200 Myr after the big bang). Again, this
gives a prediction that we wouldn't see galaxies much older than this,
but it also gives a less conservative line in the sand (less
conservative in the sense that it depends on complicated modelling and
not on the simple physics of the early universe).
-----------------------------------------------------------------------

Perhaps the simplest and most direct test of the conventional Big Bang
scenario would be the presence or absence of galaxies at z 10.

One can form a star and have it go through its evolutionary cycle in a
relatively "short" time, but forming an entire galaxy, ab initio,
would take a bit longer, me thinks.

Then again, in postmodern era one could probably argue that an entire
galaxy could spontaneously pop out of the vacuum populated by a race
of Boltzmann brains [or chimpanzees, perhaps?].

RLO
Just say "No!" to pseudo-science

In article , "Robert L.
Oldershaw" writes:

Perhaps the simplest and most direct test of the conventional Big Bang
scenario would be the presence or absence of galaxies at z 10.

Let me rephrase that: Perhaps the simplest and most direct test of the
conventional galaxy-formation scenario would be the presence or absence
of galaxies at z 10.

One can debate whether it should be 10 or 12 or whatever, but that is
not so important. (Note that the difference between 10 and 12 is much
less than between 0 and 2.)

The big bang means that the universe is expanding from a much hotter and
denser state. How galaxies form is another issue. Why is this
important? Because some people will think that problems in
understanding galaxy formation falsify the "whole paradigm" of the big
bang.

Martin Rees wrote an article in the good old QJRAS which pointed out the
importance of distinguishing "facts" based on how certain they are.
Penrose has made similar points in his books.

Just say "No!" to pseudo-science

Gladly!

jacob navia wrote in news:mt2.0-6983-1320480432
@hydra.herts.ac.uk:

Le 04/11/11 07:03, eric gisse a ecrit :
Steve wrote in
:

In ,
jacob writes:
"metal" rich galaxies incompatible with any bing bang
that would have happened only 1.7 billion years earlier.


http://www.eso.org/public/archives/r...s/eso1143/eso1
143.pdf

There's a big difference between "a surprise" on the one hand and
"incompatible" on the other. As Thomas mentioned, the timescale for
one generation of stars is 10-100 Myr, so there's plenty of time for
enrichment, especially if the IMF is top-heavy.

Its' gotta be.

Sure, if not, BB is doomed Oh catastrophe :-)

Maybe if the subject wasn't so foreign to you, the notion of stars being
more massive in the past wouldn't be so surprising?


What happened?

We are looking essentially at a random sample of galaxies 12 billion
years ago. At that time a quasar happened to exist that pointed
exactly in the direction where 12 billion years later a star would
pass, that had a small rocky planet that happened to have the right
position at the end of northern summer so that the light of that
quasar hits the CCD of the VLT after all those billion years of
journey.

There are SO many factors that happen to collaborate in making that
CCD point to that quasar (not only astronomical but also political,
the EU decided many years ago to build that VLT, those humans decided
to study astronomy etc) that it s essentially random.

And we hit two galaxies very rich in heavy elements. Just like that.

If we assume that having more heavy elements than our own sun would be
NORMAL for galaxies 12 billion years ago then ALL galaxies NOW should
have even MORE heavy elements since those elements do not go away but
accumulate with time. What would be extraordinary would be to find
heavy elements poor galaxies!!!

Did you know that different stars have different lifetimes and different
galaxies have different masses and all that together means there's a
wide spectrum of metalicity for galaxies?

Solar metalicitity, for example, only requires a few generations of
stars to generate. It isn't that hard to kick past that.


But they exist those metal poor galaxies not THAT far away from my
home. For instance I Zw 018, (UGCA 166) at only 20.98 Mpc.

Why?

If already 12 billion years ago a random sample of two galaxies
has more heavy elements than our own sun why hasn't this galaxy gotten
more of that?

Because this galaxy isn't as rich of a star former as other, more
massive, galaxies.

[snip quotemining]


Here again we have the association of low metallicity with young
galaxies

So, it is not that fair to say now that there is no association of
low "metallicity" (what a terminology) and age of a galaxy.

You not understanding what the word means does not make it an odd word.


Since all galaxies at 12 billion years are very young (less than
1Gy) it would be normal that a stupid layman like me would assume
that a high metallicity would be a surprise.

The article I quoted says:

quote
The column density NZn II = 1013.57±0.04 cm−2 in G1 is also among
the
highest ever inferred, with other systems of comparable density all
residing at z 2.9. The large column densities in G1 would indicate
the
galaxy to be massive and/or metal rich. At this high redshift, this
would make G1 a rare object.
end quote

"A RARE OBJECT" indeed. In a scientific paper you just do not use
words
like "unthinkable" as in the press release. But it is THE SAME of
course.

I note how you completely disregarded the other possibility...


All other comparable systems reside at z 2.9. The two galaxies
observed are at z 3.57.


Do you have a point beyond complaining for the sake of it?

On Saturday, November 5, 2011 4:07:12 AM UTC-4, jacob navia wrote:

If we assume that having more heavy elements than our own sun would be
NORMAL for galaxies 12 billion years ago then ALL galaxies NOW should
have even MORE heavy elements since those elements do not go away but
accumulate with time. What would be extraordinary would be to find
heavy elements poor galaxies!!!

No. As others have explained to you, the metallicity rises quickly (in
a few Myrs) in a massive starburst. The longer-lived low mass stars do
not contribute any heavy metals so there is no subsequent additional
metal enrichment.

As Savaglio et al. (the paper you are citing) write "The highest
metallicities in the local Universe are generally found in massive
quiescent elliptical galaxies, for which further metallicity
enrichment is prevented by the lack of cold gas, necessary for star
formation. High metallicities are reached very rapidly (Matteucci
1994), which means, given the old age of the stellar population, at
high redshift."

So at high redshift one expects to find many more absorption line
systems with low metallicity. But if there was a massive starburst
then one can get a metallicity as high as any observed in the local
universe. This is exactly what Savaglio et al. show in their Figure 8.
All 22 low-metallicity systems with [FeH] -2 occur at z2. But there
is no strong trend in the maximum metallicity as a function of
redshift.

The Savaglio et al. observations are important for showing the
presence of massive star formation at z = 3.57 (probably triggered
by a galaxy merger). But if you are looking for tests of standard
cosmology try the following:

1. The mean metallicity should increase as one moves from high to low
redshift. As observed. (Prochaska et al 2003 estimate that the
metallcity increases by 0.26 dex per unit redshift.)

2. The maximum metallicity observed at any redshift should not exceed
the maximum metallicity in the local universe. As observed.

[Mod. note: lines wrapped -- mjh]

In article ,
Martin Hardcastle writes:
Once star formation has started, though, and particularly if people
modelling these things are correct in believing that the first
generation of stars were very massive, then it's pretty clearly
possible to get very high abundances *in particular locations* very
quickly, at the end of the lives of the first stars, a few tens of Myr
after they formed

I agree with this. Our whole picture of heavy element formation
seems to me very far from complete, but one thing that seems clear is
that metal abundance isn't some "cosmic clock" that runs at the same
"rate" in all locations. A local example is globular clusters, which
have at least an order of magnitude range in metal abundance despite
all having roughly the same age.

Contrary to someone else's assertion, the sight line to a GRB is not
random; by definition it ends at the location of a supermassive
star. That could well be in a region of atypical metal abundance.

nobody has figured out a way of measuring meaningful
whole-galaxy elemental abundances even in the local universe.

I'm not sure I agree with this, though, depending on how strict you
are about "meaningful." We have H II regions, planetary nebulae, the
integrated starlight (both whole-galaxy and maps), and (for the
nearest galaxies) individual stars. I'd call that meaningful, though
no doubt people can disagree on exactly how to translate any given
result into a whole-galaxy average. Does anyone really doubt that
dwarf irregulars have lower metal abundances than the Milky Way, for
example?

--
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Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA