[[Mod. note -- I have rewrapped overly-long lines. -- jt]]
On Wednesday, December 28, 2016 at 5:14:16 PM UTC-5, jacobnavia wrote:
Most of the original snipped ...
I worked a few hours for this post, and I think it contain physics
arguments that I calculated by hand. I think my calculations are right,
and I posted them to you.
Steve Willner has already asked you about several of these calculations of =
yours; I too am interested in reading more about why you think they are "ri=
ght".
Well, ULAS J1120_0641 is the most dstant quasar yet discovered. GN-z11
is the most distant galaxy ever seen... until tomorrow, of course.
First, thanks for this post. It gave me an excuse to read up on an active p=
art of contemporary astrophysics that I don't follow. I haven't yet had a l=
ook at papers on the history of formation of SMBH; maybe later.
And we have also GN-z11, a one billion solar masses galaxy at just...
400 Million years after that bang. I couldn't understand how people
could explain how that fits into our cosmological models and went to the=
original science article.
{snip}
But wait a minute here. We are just a few hundred million years after a
big "bang"... Can we apply any models based on data MUCH later in the
history of the universe?
{snip}
That is completely impossible. And we aren't done yet. I am sure in the
next time astronomers will discover EVEN FURTHER OUT galaxies since the
Hubble team says 90% of the galaxies are further out and are invisible
to us.
Just wondering...
There are quite a few papers which report the results of simulations
of galaxy formation (etc) in the early universe (z~5). One in
particular directly addresses GN-z11 (preprint:
https://arxiv.org/abs/1605.08054). I recommend that you use ADS to
find papers this references, and others which cite it (and the
references) to dig into this topic in some detail. Figure 1 is, I
think, particularly impressive.
Myself, I was struck by just how conservative the models are! For
example, there's nothing about what effects CDM self-interaction
might have.
A suggestion or two: redshifts are more-or-less directly observed;
"Myr" (e.g. "million years after a big "bang"") is not. And so
actual values will depend on the (values of the) parameters used
in the models, such as the Hubble constant. In comparing "Myr"
values, don't you think it would be sensible to check what models
were used to estimate them, if only to see if they are compatible?
One more, out of order:
Stars form in VERY cold environments in galaxies, protected from
radiation by dust and cool gas.
A great many galaxies have intense star-formation in or near their
nuclei, and even our own MW has some very impressive star clusters
within a kpc or so of SgrA*. How do you explain the formation of
the stars in such clusters/environments?