A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Research
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Astronomers find most distant galaxy ever



 
 
Thread Tools Display Modes
  #1  
Old May 9th 15, 02:54 AM posted to sci.astro.research
Richard D. Saam
external usenet poster
 
Posts: 240
Default Astronomers find most distant galaxy ever

Interesting development

Astronomers find most distant galaxy ever

http://arxiv.org/abs/1502.05399

at z=7.730

only 650 Myr after the Big Bang

Richard D Saam
  #2  
Old May 11th 15, 02:40 AM posted to sci.astro.research
brad
external usenet poster
 
Posts: 102
Default Astronomers find most distant galaxy ever

On Friday, May 8, 2015 at 9:54:11 PM UTC-4, Richard D. Saam wrote:
Interesting development=20
Astronomers find most distant galaxy ever=20
http://arxiv.org/abs/1502.05399=20
at z=3D7.730
only 650 Myr after the Big Bang
Richard D Saam


IMO this is easily explained by revising the current cosmological
model whereby black holes grow with galaxies. If we remember that
the first stars were massive and that matter was unevenly distributed
in the early Universe; then we can accept that, in addition to
massive first generation stars there must also have been large
agglomerations of matter that spontaneously collapsed into massive
black holes. That means the seeds of galaxies can come first! The
gravitational energy from spinning black holes in the midst the
remaining un-collapsed matter would then cause star birth and
galactic structure. This doesn't mean black holes don't grow, only
that galactic nuclei can come earlier than the present model predicts

[[Mod. note -- The problem with this scenario is in the details:
* Large agglomerations of matter" at early-universe densities won't
actually collapse to form black holes: the matter's random motions
imply that it has some (small) amount of angular momentum, and
this blocks collapse.
* Precisely how does the "gravitational energy from spinning black
holes" cause star formation?
-- jt]]

Brad J.
  #3  
Old May 14th 15, 01:33 PM posted to sci.astro.research
Steve Willner
external usenet poster
 
Posts: 1,172
Default Astronomers find most distant galaxy ever

In article ,
"Richard D. Saam" writes:
Astronomers find most distant galaxy ever
http://arxiv.org/abs/1502.05399
at z=7.730


This is the most distant _spectroscopic confirmation_, based on a
line observed at 1062 nm and likely to be Lyman alpha.

There are _candidate galaxies_ at redshifts up to about 11. (I'm not
sure what the record is at the moment.) Spectroscopic confirmations
are difficult at high redshift not only because the candidate
galaxies are faint but also because the neutral intergalactic medium
is a strong absorber of Lyman alpha. There may soon be more
confirmations from ALMA based on the 158 micron [C II] line or
eventually from JWST based on [O II] or other UV or visible
lines. Probably most of the candidates will turn out to be at the
expected redshifts, but a few might be low-redshift objects with
peculiar (very red) spectral energy distributions.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
  #4  
Old May 14th 15, 01:39 PM posted to sci.astro.research
brad
external usenet poster
 
Posts: 102
Default Astronomers find most distant galaxy ever

[[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 Sunday, May 10, 2015 at 9:40:43 PM UTC-4, brad wrote:
=20
[[Mod. note -- The problem with this scenario is in the details:
* Large agglomerations of matter" at early-universe densities won't
actually collapse to form black holes: the matter's random motions
imply that it has some (small) amount of angular momentum, and
this blocks collapse.


So there is the formation of only stars? That same random motion
doesn't block collapse and star formation. It seems unreasonable
to not expect a range of objects; from molecular clouds right
through stars and black holes.

* Precisely how does the "gravitational energy from spinning black
holes" cause star formation?
-- jt]]


In the present Universe star formation is associated with cold
molecular clouds and the shock waves from novae. Another way to
look at this is as an energy difference before and after the
passing shock wave. If massive black holes formed in the early
Universe then there would be an energy differencebetween their
gravitational fields and the surrounding medium. The comparison
is an inverse relationship to be sure but the significance lies in
the energy differences.

Brad J.
  #5  
Old May 14th 15, 01:53 PM posted to sci.astro.research
brad
external usenet poster
 
Posts: 102
Default Astronomers find most distant galaxy ever

On Sunday, May 10, 2015 at 9:40:43 PM UTC-4, brad wrote:
=20

IMO this is easily explained by revising the current cosmological
model whereby black holes grow with galaxies. If we remember that
the first stars were massive and that matter was unevenly distributed
in the early Universe; then we can accept that, in addition to
massive first generation stars there must also have been large
agglomerations of matter that spontaneously collapsed into massive
black holes. =20


Let me flesh this out a little. For gravitational collapse to proceed
to the formation of some object the combined angular momentum of
infalling material cannot exceed a value that prohibits collapse.
This can be accomplished if there is material available to carry
away angular momentum. In the early Universe there was essentially
an unlimited amount of matter available to carry away angular momentum
allowing much more massive objects to result before the developing
object could clear a volume around itself.

[[Mod. note -- As well as low angular momentum, collapse also needs
low internal pressure.

It's instructive to consider the question of why the Sun *today*
doesn't collapse to form a black hole? The Sun currently has a radius
of about 700,000 km. To form a black hole, it (or a 1-solar-mass gas
cloud of the same size) would have to be compressed to a radius of
around 3 km, i.e., a compression by around a factor of
10,000,000,000,000,000 in volume. That would take HUGE compressive
forces... which don't seem to be available in star-forming regions.

By working out the collapse physics in detail, you can model a
protostar's collapse and estimate roughly the
radius/temperature/luminosity at which it will halt. See
http://en.wikipedia.org/wiki/Hayashi_track
for a nice introduction.
-- jt]]

That means the seeds of galaxies can come first! The
gravitational energy from spinning black holes in the midst the
remaining un-collapsed matter would then cause star birth and
galactic structure. This doesn't mean black holes don't grow, only
that galactic nuclei can come earlier than the present model predicts
=20
[[Mod. note -- The problem with this scenario is in the details:
* Large agglomerations of matter" at early-universe densities won't
actually collapse to form black holes: the matter's random motions
imply that it has some (small) amount of angular momentum, and
this blocks collapse.
* Precisely how does the "gravitational energy from spinning black
holes" cause star formation?
-- jt]]
=20
Brad J.

  #6  
Old May 15th 15, 02:52 AM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
external usenet poster
 
Posts: 273
Default Astronomers find most distant galaxy ever

In article , Steve Willner
writes:

This is the most distant _spectroscopic confirmation_, based on a
line observed at 1062 nm and likely to be Lyman alpha.

There are _candidate galaxies_ at redshifts up to about 11. (I'm not
sure what the record is at the moment.)


Note that the difference between a redshift of 7 and one of 11 is, in
most respects, less than between a redshift of 0 and one of 1. In
particular, in almost all cosmological models (and certainly in the one
which describes our universe), it corresponds to a much shorter
difference in time.
  #7  
Old May 16th 15, 03:34 AM posted to sci.astro.research
Richard D. Saam
external usenet poster
 
Posts: 240
Default Astronomers find most distant galaxy ever

On 5/14/15 7:53 AM, brad wrote:
In the early Universe there was essentially
an unlimited amount of matter available to carry away angular momentum
allowing much more massive objects to result before the developing
object could clear a volume around itself.

[[Mod. note -- As well as low angular momentum, collapse also needs
low internal pressure.


In these formation studies,
does vacuum viscosity come into play?

Ref1: http://arxiv.org/abs/0806.3165
Hydrodynamics of spacetime and vacuum viscosity

viscosity*entropy density = hbar/4pi

Richard D Saam
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Astronomers Claim to Find the Most Distant Known Galaxies (Forwarded) Robert Maas, see http://tinyurl.com/uh3t Policy 0 July 12th 07 12:26 AM
Astronomers Claim to Find the Most Distant Known Galaxies (Forwarded) Andrew Yee Astronomy Misc 0 July 10th 07 11:00 PM
Astronomers Claim to Find the Most Distant Known Galaxies (Forwarded) Andrew Yee[_1_] News 0 July 10th 07 10:12 PM
Astronomers find the most distant star clusters hidden behind anearby cluster (Forwarded) Andrew Yee Astronomy Misc 0 January 12th 07 01:04 AM
Astronomers find oldest, most distant planet: Only Bob Hope is Older VicXnews Amateur Astronomy 2 July 11th 03 09:29 PM


All times are GMT +1. The time now is 02:22 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.