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Galaxy cluster at 1100 million years after BB



 
 
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  #1  
Old January 12th 11, 11:39 PM posted to sci.astro.research
jacob navia[_5_]
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Default Galaxy cluster at 1100 million years after BB

NASA publishes the discovery of a galaxy cluster at 12.6 billion light
years:

http://www.jpl.nasa.gov/news/news.cf...y&auid=7616512

It has a central black hole of approx 30 million suns. Our own
galaxy has a central BH with only 2.6 million sun masses.
(from http://www.eso.org/public/news/eso0226/)

Now, 1.1 billion years is a VERY short time for a cluster.
Our own galaxy does 4 revolutions in that time only, imagine
building a CLUSTER of galaxies in that time.

Bsides, supposing that the black hole started growing immediately
after the big bang, it should have been eating 0.2727 sun masses a
year to achieve that mass... without interruption.

I remember when people told everyone that no cluster of galaxies
would be discovered beyond 7 billion years. Then it was 9, later
was 10.

Now we are at 12.6.
  #2  
Old January 13th 11, 07:18 PM posted to sci.astro.research
jacob navia[_5_]
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Default Galaxy cluster at 1100 million years after BB

Le 12/01/11 23:39, jacob navia a écrit :

Bsides, supposing that the black hole started growing immediately
after the big bang, it should have been eating 0.2727 sun masses a
year to achieve that mass... without interruption.


I forgot that this figure is the effective mass incorporated into
the black hole. Since the accretion efficiency is around 10%, the
black hole would need 2.7 stars like the sun each year to arrive
at that gargantuan mass only 1100 million years after the supposed Big
Bang.

A continuous line of stars, falling into the BH each 5 months
would be needed. Since the efficency is 10%, 90% of the mass of those
stars would be re-radiated, i.e. around 2.5 Mo would be left at the
accretion disk.

That enormous mass being "left over" would disturb the falling of the
following stars into the BH. I do not see how such a growth rate can
be sustained for 1100 million years.

[Mod. note: I think you may have your efficiency factors the wrong way
round. Accretion efficiency factors of 10% -- which are an order of
magnitude estimate, not a number fixed by physics -- usually mean that
10% of the mass-energy is radiated, not that only 10% of the mass
makes it in. There are real problems in understanding black hole
growth, but it's not necessary to exaggerate the problem by an order
of magnitude -- mjh]
  #3  
Old January 13th 11, 09:08 PM posted to sci.astro.research
Phillip Helbig---undress to reply
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Default Galaxy cluster at 1100 million years after BB

In article , "Robert L.
Oldershaw" writes:

Don't you just love those "adjustable" theories that never take a
scientific stand, as in a definitive prediction, but rather stretch to
fit the new data in a most plastic manner. Very postmodern.


Like those which predicted one-solar-mass objects as the dark matter,
then stopped predicting them when observations said otherwise?

It reminds me of the endless search for the "transition to rigorous
(as opposed to statistical) cosmological homogeneity" which has
undergone a similar sequence of multiple crossings of "lines drawn in
the sand", followed each time by new "lines drawn in the sand".

Did fundamentally inhomogeneous models ever get the attention and
respect they have always deserved?


Yes they did. It was not much attention since they didn't deserve much.

Not a chance. They are still sent
to the back of the bus. One can publish papers on this subject, but
one can also expect flak and ignore-ance. Just ask Pietronero and
Labini

Same as it ever was.


Indeed---a good summary of their numerous papers, which have been saying
the same thing for decades despite tremendous observational advances
during that time.
  #4  
Old January 14th 11, 12:28 PM posted to sci.astro.research
jacob navia[_5_]
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Default Galaxy cluster at 1100 million years after BB

Le 13/01/11 19:18, jacob navia a écrit :
Le 12/01/11 23:39, jacob navia a écrit :

[Mod. note: I think you may have your efficiency factors the wrong way
round. Accretion efficiency factors of 10% -- which are an order of
magnitude estimate, not a number fixed by physics -- usually mean that
10% of the mass-energy is radiated, not that only 10% of the mass
makes it in. There are real problems in understanding black hole
growth, but it's not necessary to exaggerate the problem by an order
of magnitude -- mjh]


You are right. I misunderstood
Accretion, black holes, AGN and all that.....
Andrew King Theoretical Astrophysics Group, University of Leicester, UK
http://www.exp-astro.phys.ethz.ch/se...tures_King.pdf

I was mislead by page 62 of that document where he speaks about 10%
efficiency.

Question then:

What is the maximal black hole accretion rate?
There is a super massive black hole already at 13 billion years, i.e.
only 700 million years after that "bang"...
  #5  
Old January 14th 11, 02:59 PM posted to sci.astro.research
Martin Hardcastle
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Default Galaxy cluster at 1100 million years after BB

In article ,
jacob navia wrote:
Question then:

What is the maximal black hole accretion rate?


Answer: it depends.

For example, suppose I collect a bunch of stars, extract all their
angular momentum, and drop them one by one on radial trajectories into
a non-rotating black hole which already has a mass large enough that
the event horizon is the typical stellar radius. The accretion rate
is very high (limited only by how fast I can shove the stars in
without them colliding), the radiation generated is zero -- all the
kinetic energy generated as the star falls in is carried in with it
over the event horizon (advected). Obviously nobody is out there doing
this, but it illustrates that you have to understand what sort of
material is accreting and in what way before you can answer questions
about black hole growth rate.

Standard calculations such as the Eddington limit implicitly assume
radiatively efficient flows with an efficiency ~ 10%. They also assume
quasi-spherical symmetry. It is certainly possible (& observed) for
systems to exceed the Eddington 'limit'.

If you go to ADS and search abstracts for 'black hole growth early
universe' or something along those lines you will find a bunch of
people discussing different scenarios for black hole growth, including
some where the black holes do indeed grow rapidly without producing
much radiation in the early universe. Everybody working in this area
is aware (and has been for some time given the existence of high-z
quasars) that this needs to be understood.

Martin
--
Martin Hardcastle
School of Physics, Astronomy and Mathematics, University of Hertfordshire, UK
Please replace the xxx.xxx.xxx in the header with herts.ac.uk to mail me
  #6  
Old January 18th 11, 06:26 AM posted to sci.astro.research
Thomas Smid
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Default Galaxy cluster at 1100 million years after BB

On Jan 12, 10:39 pm, jacob navia wrote:


Bsides, supposing that the black hole started growing immediately
after the big bang, it should have been eating 0.2727 sun masses a
year to achieve that mass... without interruption.


What leads you to assume that the central black hole has acquired its
mass by means of accretion? In the process of the formation of our
solar system about 99.9% of the total mass have directly collapsed
into the central object (our sun). So it is not a big deal if 0.03% of
the mass of a typical galaxy (10^11 solar masses) have directly
collapsed into the central object. Besides, black hole or not, such an
object would anyway only be visible in the X-ray region of the
electromagnetic spectrum due to the high temperature associated with
its gravitational energy.


I remember when people told everyone that no cluster of galaxies
would be discovered beyond 7 billion years. Then it was 9, later
was 10.

Now we are at 12.6.


It hardly matters. Big-Bang cosmologists can practically accommodate
any observations by adjusting the free parameters in their equations
accordingly.

Thomas
  #7  
Old January 18th 11, 06:27 AM posted to sci.astro.research
Dan Birchall[_3_]
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Default Galaxy cluster at 1100 million years after BB

(jacob navia) wrote:
NASA publishes the discovery of a galaxy cluster at 12.6 billion light
years:

http://www.jpl.nasa.gov/news/news.cfm?release=2011-013
&cid=release_2011-013&msource=11013&tr=y&auid=7616512


I noticed this release (and several copies of it on science news
web sites) but have been unable to find the actual paper(s) behind
it all.

The articles mention that the telescope I operate was used for part
of the research, so I'm of course curious about which of our
instruments was used.

I know the Subaru/XMM-Newton Deep Survey uses our prime-focus camera
(SuprimeCam), but I think their field is in Cetus, while this one
is in Sextans.

Anybody got a link to the paper(s)?

--
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naoj | Views I express are my own, certainly not those of my employer.
...org | Oh wicked, bad, naughty, _evil_ Dan! He is a _naughty_ person.
  #8  
Old January 19th 11, 06:50 PM posted to sci.astro.research
jacob navia[_5_]
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Default Galaxy cluster at 1100 million years after BB

Le 18/01/11 06:26, Thomas Smid a ?crit :
On Jan 12, 10:39 pm, jacob wrote:


Bsides, supposing that the black hole started growing immediately
after the big bang, it should have been eating 0.2727 sun masses a
year to achieve that mass... without interruption.


What leads you to assume that the central black hole has acquired its
mass by means of accretion?


Nothing. If you read what I wrote I just said that it must have
increased its mass by 0.27 solar masses per year. Then I tried to figure
out how much REAL mass would be needed to inject 0.27 M0 into the
black hole since the injection process is not 100% efficient.
THERE I made a mistake. It is more than 10% of the mass of a star
that can be accretted, but probably not more than 50%. Even at 50%,
we would need a star of the mass of the sun each 2 years.

Assuming:

(1) At the start of the big bang there were no atoms, just some
"particle soup"
(2) 1100 million years later we find a blackhole that has 30 million
solar masses, made by atoms falling down into it.

This means that somehow that black hole went from 2 solar masses
(a stellar black hole) to 30 million in that time, i.e. 0.27 M0
per year in average.

In the same period, a CLUSTER of galaxies is created. Not only
galaxies but a CLUSTER.

Now, coming back to our huge hole, it could grow by swallowing whole
galaxies of course. The only problem is that the process is quite long
and takes MUCH more than a billion years for a single galaxy.

How then?

In the process of the formation of our
solar system about 99.9% of the total mass have directly collapsed
into the central object (our sun). So it is not a big deal if 0.03% of
the mass of a typical galaxy (10^11 solar masses) have directly
collapsed into the central object.



Yes, it is surely not a big deal, as you say,
but that is not the point. The point is that it is a BIG
deal to do it in 1100 million years only!

To collapse that mass directly in the form of gas, etc, the
ring around the BH gets very hot, and keeps further infalling
gas AWAY. Then, the ring must cool, lose angular momentum and
get incorporated into the BH. That takes TIME.

Besides, black hole or not, such an
object would anyway only be visible in the X-ray region of the
electromagnetic spectrum due to the high temperature associated with
its gravitational energy.


Yes, but since light gets red shifted, we should be able to see
it now since the X rays are no longer X rays.

[[Mod. note -- That does depend on the redshift. For example, a
soft X-ray source at a redshift z=10 could well wind up in the
millimeter-wave range, where (alas) not many astronomical
observations have yet been made.
-- jt]]


I remember when people told everyone that no cluster of galaxies
would be discovered beyond 7 billion years. Then it was 9, later
was 10.

Now we are at 12.6.


It hardly matters. Big-Bang cosmologists can practically accommodate
any observations by adjusting the free parameters in their equations
accordingly.

Thomas


But that is precisely the point. We have a theory that can always be
"shifted" to please any new observations.
  #9  
Old January 21st 11, 03:41 AM posted to sci.astro.research
Phillip Helbig---undress to reply
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Default Galaxy cluster at 1100 million years after BB

In article
,
"Robert L. Oldershaw" writes:

False. There is ongoing debate over what % of the dark matter is
observed to be in the form of stellar-mass black holes.


First, no one has OBSERVED any sort of black hole in observations
designed to detect dark matter; at best, black holes are inferred.

A microlensing
signature has been observed by several microlensing groups.


No one denies that microlensing has been observed. The question is how
much microlensing would one expect if an appreciable fraction of the
dark matter were in compact objects, and the answer is that one would
expect much more than is observed.

The
interpretation of what they have observed and the statistics of the
population are not decided scientifically.


Then how are they decided?
  #10  
Old January 21st 11, 03:42 AM posted to sci.astro.research
Dr J R Stockton[_97_]
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Default Galaxy cluster at 1100 million years after BB

In sci.astro.research message ,
Tue, 18 Jan 2011 00:27:42, Dan Birchall
posted:

(jacob navia) wrote:
NASA publishes the discovery of a galaxy cluster at 12.6 billion light
years:

http://www.jpl.nasa.gov/news/news.cfm?release=2011-013
&cid=release_2011-013&msource=11013&tr=y&auid=7616512


Anybody got a link to the paper(s)?


Ask Whitney Clavin.

--
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Web http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms and links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.
 




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