New problems for current cosmology

In article ,
jacobnavia writes:
OK. Let's suppose that the article I cited about that galaxy at z=11 is
confirmed (arXiv:1502.05681v2 [astro-ph.GA] 22 Feb 2015)

If not that galaxy, there are almost certainly others. Still
relatively few galaxies at z=11 compared to the numbers that formed
later, but not zero.

A hot gas can't collapse gravitationally because gravity can't
counterbalance the kinetic energy of the gas particles.

The Jeans mass is larger at higher temperatures. That doesn't mean
collapse is impossible, but it only occurs in the largest over-
densities.

That situation is made worst by the absence of grains and heavy
elements that could be used as condensation helpers.

I'd say "coolants" rather than "condensation helpers," but the
principle is right.

At z=20 (t=180 MY) we have a colder situation around 57,33 Kelvins, so
let's start there.

I'd probably guess later, but z=20 is fine for an order of magnitude
estimate.

We can suppose that the first molecular clouds
collapse in the early universe started about t=180 MY.

It's not clear molecular hydrogen can form without dust, and there
are no heavy elements to make molecules from. Nevertheless, gas
clouds will collapse wherever the density and mass are high enough.

420-180 -- 240 MY.

Practically an eternity in this context.

In only 240 MY that galaxy formed so many billions of stars that its
light reaches us

By "reaches us," you mean with sufficient luminosity for
detection. Estimated stellar mass (which is highly uncertain given
the data in Fig 1 of the preprint) is 10^10 Msun. Star formation
rate is perhaps 100 Msun/yr, so only 10^8 years are needed. What's
the problem?

More to the point, the stars we see are only the very massive ones.
The stellar mass estimate is based on a "Salpeter IMF," which
_assumes_ that there are a bunch of less massive stars accompanying
the stars we actually see the light of. There is exactly zero
evidence for that assumption, but it is fair and well understood.

Normal stars like the sun take 50 MY to form. Huge stars take a few
hundred thousand years. Now:

As noted in my earlier post, there are problems with that first
statement. Regardless of that, it's the "huge stars" that matter.

1) It can be possible to form a huge galaxy in 240 MY if all the stars
are HUGE stars that build in much less than a million years.

No requirement that _all_ the stars be huge; only that there be
sufficient numbers of the huge ones. Which is what we see. Lower
mass stars wouldn't produce the observed light, which was emitted in
the UV.

2) If that is the case the light of that galaxy should be highly blue.

The observations are too uncertain to say anything for that
particular galaxy, but in general high-z galaxies are blue.
Technically, beta = d f_lambda/d lambda = -2 around rest wavelength
150 nm is typical.

3) Problems with that, is that a sudden "explosion" building billions of
stars in such a short time would considerably heat the gas in that
galaxy, making further star formation very difficult.

Locally, it's only the supernovae that disrupt molecular clouds.
Winds and radiation from O stars rearrange the gas and may even
trigger star formation. What's happening in the very different
environment of the early universe is unknown.

And another problem (this one fatal) is the following: How come that we
can see that galaxy at all? A chance alignment? That galaxy is exactly
at the right position behind a cluster of galaxies in the foreground.

I don't see why that's a problem, let alone "fatal." The observers
searched enough area to expect to find some examples with the
appropriate alignment.

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

[[Mod. note -- Please limit your text to fit within 80 columns,
preferably around 70, so that readers don't have to scroll horizontally
to read each line. I have manually reformatted this article. -- jt]]

On Saturday, September 12, 2015 at 11:57:03 PM UTC-4, jacobnavia wrote:

=20
The farther we see, the more galaxies we see.

Yes, we keep seeing galaxies at higher redshift but they don't look
anything like nearby galaxies. Spiral galaxies are almost impossible
to find at z 2, and 80% of galaxies at z~3 are classified as peculiar
(random distribution of star-forming regions). There is also dramatic
size evolution, with high redshift galaxies being more compact.

Chris Conselice gives a nice review of the evolution of galaxy structure
results at
http://ned.ipac.caltech.edu/level5/M...onselice4.html
Look in particular at Figures 8 and 11.

So you are correct that we shouldn't see spiral or elliptical galaxies
after only 420 Myrs. But there is no reason not to expect to see massive
star formation.

In article ,
"Phillip Helbig (undress to reply)" writes:
one still doesn't have a theory
which can calculate the initial mass function of stars.

What astounds me is how much progress we've made in cosmology and how
little we've made in star formation in the last 30-40 years. I
expected the opposite and was wrong. When I sat on a time assignment
panel just over a year ago, we joked about every proposal starting
out with the sentence "Formation of massive stars is poorly
understood." I don't even see much hope for a breakthrough in the
next 30 years, but maybe I'm as wrong now as I was back then about
progress in cosmology.

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

On Thursday, September 24, 2015 at 3:40:51 PM UTC-4, Steve Willner wrote:

=20
What astounds me is how much progress we've made in cosmology and how
little we've made in star formation in the last 30-40 years. I
expected the opposite and was wrong. When I sat on a time assignment
panel just over a year ago, we joked about every proposal starting
out with the sentence "Formation of massive stars is poorly
understood." I don't even see much hope for a breakthrough in the
next 30 years, but maybe I'm as wrong now as I was back then about
progress in cosmology.
=20

today's report (Japanese group) of massive, dead ellipticals
with an age of 10 b.y. [For the search engine challenged: "The Ages,
Metallicities, and Element Abundance Ratios of Massive Quenched
Galaxies at z ~ 1.6," M. Onodera et al., 2015, Astrophysical Journal,
DOI: 10.1088/0004-637X/808/2/161]=20


So, in 3.7 billion years, these galaxies were born from a "soup of
subatomic particles", grew to immense masses of stars surrounding
a supermassive black hole, went through lengthy stellar evolution
and then entered the long decline to decrepitude?

In 3.7 billion years? I think we are going to see a lot of arm-waving
to explain this. More likely is growing evidence that we are quite
clueless when it comes to the "early universe" and galactic physics.

RLO
http://www3.amherst.edu/~rloldershaw
Fractal Cosmology=20
Help keep our newsgroup healthy; question the prevailing dogma.

On 9/26/2015 4:40 PM, Robert L. Oldershaw wrote:
On Thursday, September 24, 2015 at 3:40:51 PM UTC-4, Steve Willner wrote:
...
today's report (Japanese group) of massive, dead ellipticals
with an age of 10 b.y. [For the search engine challenged: "The Ages,
Metallicities, and Element Abundance Ratios of Massive Quenched
Galaxies at z ~ 1.6," M. Onodera et al., 2015, Astrophysical Journal,
DOI: 10.1088/0004-637X/808/2/161]=20

So, in 3.7 billion years, these galaxies were born from a "soup of
subatomic particles", grew to immense masses of stars surrounding
a supermassive black hole, went through lengthy stellar evolution
and then entered the long decline to decrepitude?

Well, at least the "soup of subatomic particles" phase did not
take too much of the total time in this process, I would expect.

In 3.7 billion years? I think we are going to see a lot of arm-waving
to explain this.

Why would that be the case? 3.9Gy does not exceed most supported
estimates for the age of the universe (although admittedly the
range starts at roughly 4,000 years..)

More likely is growing evidence that we are quite
clueless when it comes to the "early universe" and galactic physics.

My understanding was this: (may someone correct me if I'm wrong)
1) Population III stars evolved fast due to low metalicity
2) A smaller universe had more collisions between galaxies,
stirring them up, so in the early Gys galactic shape
evolution and central black hole formation was also faster.

--
Jos

On Saturday, September 26, 2015 at 10:40:27 AM UTC-4, Robert L. Oldershaw wrote:


today's report (Japanese group) of massive, dead ellipticals
with an age of 10 b.y.

"Dead" here simply means that the galaxy is not forming new stars.
In a starburst system, the galaxy can be "dead" a few million years
after the starburst. Of course, the lower mass stars in the galaxy
can continue to shine for many billions of years after new star
formation has ceased.

In our local neighborhood, there are massive dead ellipticals with
an age of 13 Gyr (e.g. M87). The Japanese group show that their
galaxies at z=1.6 are consistent with being the progenitors of the
ellipticals at z = 0. (Note that we do *not* find 13 Gyr old galaxies
at z = 1.6, which just as expected). These observations
strongly support the standard evolutionary history of the universe.

The authors also add to the considerable evidence for a strong
quenching of star formation around z = 2.2. *Why* this occurs
is still a topic of active debate (e.g. http://arxiv.org/abs/1504.04021 )

More likely is growing evidence that we are quite
clueless when it comes to the "early universe" and galactic physics.

Well, somebody is clueless...

RLO
http://www3.amherst.edu/~rloldershaw
Fractal Cosmology

On Sunday, September 27, 2015 at 11:11:05 PM UTC-4, wlandsman wrote:

Well, somebody is clueless...

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

Full agreement here.

I have an important scientific question for all readers of SAR.

Are you comfortable with idea of the entire cosmos, including
all matter and all space-time, suddenly popping out of, what, "the
vacuum", nothing, no when?


RLO
http://www3.amherst.edu/~rloldershaw
Fractal Cosmology
Help keep our newsgroup healthy; question the prevailing dogma.

[[Mod. note -- I'm accepting this posting for the newsgroup on the
grounds that the origins of the universe (big bang) is reasonably
within the scope of this newsgroup. However, discussion needs to
address the *science* (e.g., is there a theoretical model? What other
predictions follow from it?) -- in the absence of some scientific
reasoning, simple statements of opinion (including one's level of
comfort with various ideas) are probably not appropriate for the
newsgroup.
-- jt]]

On Tuesday, September 29, 2015 at 2:03:53 PM UTC-4, Robert L. Oldershaw
wrote:

Are you comfortable with idea of the entire cosmos, including
all matter and all space-time, suddenly popping out of, what, "the
vacuum", nothing, no when?

To be honest, my puny human mind is not comfortable with either
the concept of a universe that exists forever, or with the alternative
concept that at some point the universe was created from nothing.
So I have no preference between cyclic models where the current big
bang expansion is part of an infinite series of expansions and
contractions, and models where the current big bang is a singular
event. But we are not yet talking science, because there are no
observations (yet) that can distinguish the two possibilities.

Of course, the Lambda CDM model provides an excellent description
(with only 6 free parameters) of the past 13.7 billion years of the
universe. This is established science with thousands of
supporting observations, including some that Rob Oldershaw has
kindly posted to this group. In the present thread he posted the
abstract of a paper showing that the ~3Gyr old progenitors of present
day 13 Gyr old giant elliptical galaxies can be seen at z=1.6
(consistent with the timescale established with e.g. Planck/WMAP).

--Wayne

On Tuesday, September 29, 2015 at 11:02:02 PM UTC-4, wlandsman wrote:
=20
To be honest, my puny human mind is not comfortable with either
the concept of a universe that exists forever, or with the alternative
concept that at some point the universe was created from nothing.
So I have no preference between cyclic models where the current big
bang expansion is part of an infinite series of expansions and
contractions, and models where the current big bang is a singular
event. But we are not yet talking science, because there are no
observations (yet) that can distinguish the two possibilities.
=20
Ok. When theorists tell us what happened within the first 10^-30
sec after the Big Bang, are they talking science, or are they talking
something else. Does any modeling of what went on before recombination
qualify as science? If so, where exactly is the line between
untestable speculation and testable science?

So far we have one person (me) unwilling to throw out conservation
of mass/energy, conservation of angular momentum and the principle
of causality in favor of a completely speculative something-from-nothing
beginning of the cosmos.

And we have one person (WL) who says he is uncomfortable with any
version of what was going on at the exact moment of the BB.

Well.... don't other readers have thoughts on this question? I would
really like to hear from people who accept the something-from-nothing
beginning of the whole shebang. Surely these people are out there
because it is the prevailing story one reads in Nature, Sci Amer.,
NYT, ..., and from all the luminaries who are dutifully quoted in
the media.

RLO
http://www3.amherst.edu/~rloldershaw

In article ,
"Robert L. Oldershaw" writes:

Ok. When theorists tell us what happened within the first 10^-30
sec after the Big Bang, are they talking science, or are they talking
something else. Does any modeling of what went on before recombination
qualify as science? If so, where exactly is the line between
untestable speculation and testable science?

How about testability? Big-bang nucleosynthesis happened before
combination (no "re" since there was no combination before) and is a
good example of a scientific theory.