More trouble for big bang theory

Le 10/11/11 23:00, Steve Willner a ecrit :
In ,
jacob writes:
So, you say that the average abundance should be low, but
that we hit by chance a "special spot"...

Not "by chance." The relevant type of GRB -- and I can never keep
straight which are long and which are short -- is thought to come
from a hypermassive star. Thus _by definition_ the line of sight
ends in a spot that had a hypermassive star in it. That is reason
expect, or at least not be surprised by, atypical metal abundance.


That could be an explanation, yes, but the problem is that this GRB
illuminates (goes through) its own galaxy and a
second one. As far as I understand this, this HUGE column of
nothing less than 12 billion light years (z=3.7 means age of 1.723 Gy,
so 13.7-1.7 -- 12 Gy) is dominated by the lines of these two
interacting galaxies. I cite from the abstract of the original
publication:

quote We report on the surprisingly high metallicity measured in two
absorption systems at high redshift, detected in the Very Large
Telescope spectrum of the afterglow of the gamma-ray burst GRB 090323.
The two systems, at redshift z = 3.5673 and z = 3.5774 (separation
delta v ~ 660 km s^-1) are dominated by the neutral gas in the
interstellar medium of the parent galaxies. end quote

I understand this as meaning that the neutral gas in those two galaxies
is the one that generates this spectrum lines. This has not a lot to do
with the origin of the GRB that is not discussed at all. The GRB is
used as a light that goes through those galaxies illuminating them
with its powerful beam.


Very massive galaxies apparently formed their metals very early. We
expect to see some of these, just not huge numbers. It's too early
yet to have adequate statistics, and anyway, the observation that
started this thread is not a random sample.


I see your point: GRBs could bias our observations because they could
happen in special environments of high metallicity. OK. But a GRB
is just a light. WHERE that light goes through it is independent of
the GRB since it depends of the orientation of the GRB beam and what
is in its neighborhood. Note that TWO high metallicity galaxies are
reported.


13.2 BILLION years later we haven't gotten to that point
in Zinc.

You need to subtract the 4.5 Gyr age of the Sun.

Correct. My mistake.

Thanks for your answer Mr Willner.

[Mod. note: non-ASCII characters removed. Please, when cutting and
pasting from papers, make sure you don't include non-printable
characters -- mjh]

jacob navia wrote in news:mt2.0-17300-1320826268
@hydra.herts.ac.uk:

Le 05/11/11 11:09, Phillip Helbig---undress to reply a écrit :
In , "Robert L.
writes:


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.


Look, at Z=11 temperature of the CMB should have been

T(z) = t(z=0) * (z+1) = 2.73 * 12 = 30.03 Kelvin [1]

At z = 30 CMB is at 81.9 Kelvin.

At SOME z temperature is too high to have a galaxy or even a star.
Already 30 Kelvin is much higher than the temperatures in the
cold dark clouds that produce stars (around 10 kelvins) ...

Gravitational collapse thus the existence of a star will only be weakly
impacted by temperature of its' stellar factory.

Since the temperature will be the same in all directions I am unclear what
effect you think this would have on formation.

[...]

In article ,
eric gisse writes:
The Eddington limit is HUGE. It doesn't even become relevant until you
are getting into quasar luminosities,

Not so. It was initially derived for stars. At least the start of
the discussion at
http://en.wikipedia.org/wiki/Eddington_luminosity
looks right to me, but I haven't checked the whole text.

Actually, I wonder if anyone has a figure on the overall percentage of
mass-energy conversion over a star's lifetime...

Nucleosynthesis can release at most about 1% of the mass energy, but
gravitational energy makes up part of a star's luminosity.

There's probably a direct relation between the mass of a galaxy and
its' overall metalicity.

There's still lots of work to do on that subject, but it seems that
more massive galaxies are _in general_ more metal rich and formed
their metals much earlier than less massive galaxies. It wouldn't
surprise me if there are exceptions; as I say, this is very much work
in progress. I may be missing something, though, so don't take this
paragraph too seriously.

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

In article ,
eric gisse writes:
We have the Tully-Fisher relation which relates the mass of the galaxy to
its' luminosity, and we have a relation (not sure if it is named) between
the mass of the galaxy's central black hole and its' overalll mass.

The relation is usually called the Magorrian Relation, but it relates
the black hole mass to the galaxy _bulge_ mass, not total mass. See
http://www.astr.ua.edu/keel/agn/quasar40.html
which is a really good article but might have more than you want to
know. The Wikipedia article at
http://en.wikipedia.org/wiki/M-sigma_relation
is in serious need of updating, though I don't see anything that's
strictly wrong. (The bulge:black hole mass ratio is probably closer
to 2000:1 than 1000:1, though.)


[Sorry to include a non-astronomical rant here, but there's something
I can't stand anymore. _Its_ with no apostrophe is a possessive
pronoun; _it's_ with an apostrophe is a contraction for "it is."
There is no such word as _its'_. These are easy to confuse, and I
mistake them myself once in awhile, but could we all please try to
get them right?]

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