The sea of galaxies comes slowly into view

In article ,
jacobnavia writes:
http://www.eso.org/public/archives/r...5/eso1545a.pdf
That article says (page 16)
"Our results indicate that some very massive galaxies are
present since the universe was only a billion years old."

The milky way is more than 10Gy old. How a galaxy TWICE AS MASSIVE can
appear in just 945My (z=6) ??

What the article actually says is that such galaxies appear in
significant numbers between z = 5 and 6.

At lower redshifts, more massive galaxies form faster than less
massive galaxies. Why is it surprising that the same thing is found
at z 5?

And the authors say that many more galaxies even more massive are
lurking behind, obscured by dust.

If so, I missed that. The observations can't rule out such galaxies,
but where does the paper say they exist?

This confirms what I have reported
here in a previous discussion: the sea of galaxies waiting for us behind
the farthest galaxies that we can see now.

Did you look at the space density plots (Figs 8 and 13)? Why do you
think there are more galaxies at higher redshifts? Of course there
are some (as reported in other papers), but so far the masses and
space densities at z6 are much lower than at 5z6.

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

Le 25/11/2015 00:52, Steve Willner a écrit :
In article ,
jacobnavia writes:
http://www.eso.org/public/archives/r...5/eso1545a.pdf
That article says (page 16)
"Our results indicate that some very massive galaxies are
present since the universe was only a billion years old."

The milky way is more than 10Gy old. How a galaxy TWICE AS MASSIVE can
appear in just 945My (z=6) ??

What the article actually says is that such galaxies appear in
significant numbers between z = 5 and 6.


Well that is the same!


At lower redshifts, more massive galaxies form faster than less
massive galaxies. Why is it surprising that the same thing is found
at z 5?


Because we have been told by big bang proponents that the early galaxies
were quite small!

They are not.

At what z we will still accept that the theory has not been rejected by
observations?

I suppose that when we find old and dusty galaxies at z=7 the bang will
(hopefully) go away.


And the authors say that many more galaxies even more massive are
lurking behind, obscured by dust.

If so, I missed that. The observations can't rule out such galaxies,
but where does the paper say they exist?


quote
The presence of very massive (Mst = 2*10^11 M0) galaxies in our sample
at 5 = z 6 and the virtual absence at 6 = z 7 provide a strong
constraint on the evolution of the GSMF highest-mass end, which suggests
that the appearance of such massive galaxies took place in the few
hundred million years of elapsed time between z ~ 6 and z ~ 5.
end quote

So, the authors arrive at the conclusion that in a few hundred million
years the massive galaxies appear out of the blue. That is quite a
bitter pîll to swallow... how can those massive galaxies appear almost
instantaneously?

Then, the authors offer an alternative to that:
quote
The only alternative to this conclusion is that, among the [4.5] 23
galaxies that remain unidentified and/or those that have no redshift
determination in our current sample, there is a population of very
massive galaxies at z 6 that are significantly dust obscured. One
possible candidate for such galaxies was discussed by Caputi et al.
(2012) in one of the CANDELS fields, but the level of dust obscuration
(AV = 0.90 mag) is atypical, given our current knowledge of galaxies in
the early universe (but see Oesch et al. 2015). Further studies in other
fields, as well as future follow-up with JWST and ALMA, are necessary to
confirm whether such sources exist at z 6.
end quote

You (may) know that any frontal attack of big bang theory provokes a
banning of the concerned astronomer. Doubts about the theory must be
voiced with extreme calm... I am surprised the authors express
themselves quite clearly in the paper.

quote
In this paper we find only one massive galaxy candidate at z = 6 over
the UltraVISTA ultradeep stripe area (∼0.8 deg2).
end quote

So, we have a galaxy with z=6!

quote
The best-fit SED indicates that this is a 0.1 Gyr old galaxy at zphot =
6.04 (the age of the universe is ∼0.9 Gyr at z = 6), with extinction AV
= 0.30. This source is not detected at 24 mm, as expected for such a
distant source (unless it were an AGN). The derived stellar mass is

Mst approx 1.8 * 10^11 M0.
end quote

This confirms what I have reported
here in a previous discussion: the sea of galaxies waiting for us behind
the farthest galaxies that we can see now.

Did you look at the space density plots (Figs 8 and 13)? Why do you
think there are more galaxies at higher redshifts? Of course there
are some (as reported in other papers), but so far the masses and
space densities at z6 are much lower than at 5z6.


So far, because of instrument problems. We are at the limits of what
astronomy can yield for observers...

Big bang theory is decaying slowly. There isn't now any "smoking gun".
The theory holds because people (specially astronomers that have
invested their whole career in expanding and honing that theory) do not
want to see the trend in the observations.

And that is human, I do not blame them or want their demisse!

Maybe we have to wait for more powerful scopes, that is all.

Plese note that a single OLD galaxy at z=8 or 9 suffices to disprove big
bang theory.

[[Mod. note -- Actually, a single OLD galaxy at z=8 or 9 *might*
(a) disprove big bang theory, and/or
(b) it might disprove whatever combination of theoretical models
and observation that were used to infer that the galaxy was "old".

Given our poor state of knowledge about early-universe galaxy
formation/evolution, (b) doesn't seem implausible to me.
-- jt]]

In article , jacobnavia
writes:

Because we have been told by big bang proponents that the early galaxies
were quite small!

Assuming this is true, it was a guess, but IS RELATED TO GALAXY
FORMATION AND NOT TO THE BIG BANG PER SE.

Even if there are surprises, problems, whatever with galaxy formation,
why do you then conclude that the idea of the big bang is wrong?

At what z we will still accept that the theory has not been rejected by
observations?

When a DEFINITIVE prediction has been convincingly falsified.

I suppose that when we find old and dusty galaxies at z=7 the bang will
(hopefully) go away.

Why hopefully? Do you have an axe to grind?

So, the authors arrive at the conclusion that in a few hundred million
years the massive galaxies appear out of the blue. That is quite a
bitter pill to swallow... how can those massive galaxies appear almost
instantaneously?

A few hundred million years is not instantaneous, not even within the
context of galaxy formation.

You (may) know that any frontal attack of big bang theory provokes a
banning of the concerned astronomer.

Some see it that way, but it is usually not true. Halton Arp wrote a
book where he challenges conventional cosmology, including the big bang,
in a quite aggressive manner. The dust-jacket flap said "He is on the
staff of the Max Planck Institute for Astrophysics". I'm sure any
astronomer would be perfectly happy at being banned to a Max Planck
Institute.

Plese note that a single OLD galaxy at z=8 or 9 suffices to disprove big
bang theory.

[[Mod. note -- Actually, a single OLD galaxy at z=8 or 9 *might*
(a) disprove big bang theory, and/or
(b) it might disprove whatever combination of theoretical models
and observation that were used to infer that the galaxy was "old".

Given our poor state of knowledge about early-universe galaxy
formation/evolution, (b) doesn't seem implausible to me.
-- jt]]

Or it could falsify some theory of galaxy formation.