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Did LIGO Detect Dark Matter? - New paper on arxiv.org



 
 
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  #11  
Old March 13th 16, 09:15 AM posted to sci.astro.research
Nicolaas Vroom
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Posts: 216
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

Op donderdag 3 maart 2016 08:46:37 UTC+1 schreef Robert L. Oldershaw:

http://arxiv.org/abs/1603.00464

Title: Did LIGO detect dark matter?


The interesting part about the article is that nowhere they mention
the words baryonic versus nonbaryonic. Instead what they use are the
concepts dark matter (7x) versus luminous matter (3x).
This are typical a human based concepts and IMO should not be used.
In a certain sense because we can not see BH's, by definition
we should call BH: dark-matter-hole's

The most important discovery with the Ligo experiment is the detection of
very small BH's in the order of 30 Sun masses.
The next question is what is the evolution path and what is their make up.

The most logical explanation is that they are normal stars which in some
way collapsed. That means they are baryonic.
Gas clouds which collapsed are a different option.
The next question how many of these BH's are there in an average galaxy.
If there are many, you can use them to explain the Galaxy Rotation curve
and you even do not need non-baryonic matter.
What makes this assumption, in this context, more acceptable is that these
pBH's easily can grow in size by merging with other small or large stars
(baryonic matter).

In the article they also mention the halo of a galaxy.
That means a galaxy consists of a bulge with radius r, a disc with a
radius "10r" (the disc is more or less flat) and an halo consisting
of everything outside the bulge and the disc with a radius of "10r".
In side that space you have the birthplace of these pBH's.

The question is what will happen with these pBH's?
IMO they will slowly travel towards the disc and the bulge.
That is IMO not so much of a problem when they are baryonic but
much more a problem when they are non-baryonic.

IMO to assume that pBH's are nonbaryonic creates more problems than
it solves except that if we assume that our sun is also for a large
part non-baryonic.

Nicolaas Vroom
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  #12  
Old March 13th 16, 09:25 AM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

In article , "Richard D. Saam"
writes:

This assumes neutral hydrogen in gas form.
What if the neutral hydrogen were in aggregate or clumped form?


One can argue that such neutral hydrogen aggregates
would have to be extremely cold (2.7K) to form
and the present BBN models "baryon budget" do not allow them
beyond the 4.9% ionized form
but the fact is that current analytical methods
(other than gravitational lensing methods)
cannot detect them if they exist.


This sounds to me like Russell's teapot or back issues of the ApJ as
dark matter. Unless you have a convincing reason why something should
exist (he how they can be so cold), saying "we can't (yet) rule it
out observationally" doesn't make a very strong case.
  #13  
Old March 13th 16, 12:42 PM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

In article , Nicolaas Vroom
writes:

http://arxiv.org/abs/1603.00464

Title: Did LIGO detect dark matter?


The interesting part about the article is that nowhere they mention
the words baryonic versus nonbaryonic. Instead what they use are the
concepts dark matter (7x) versus luminous matter (3x).
This are typical a human based concepts and IMO should not be used.
In a certain sense because we can not see BH's, by definition
we should call BH: dark-matter-hole's


These days, dark-matter almost universally (pun, as always, intended)
means non-baryonic matter. Due to the no-hair theorem, we cannot say
whether these black holes formed from baryonic or non-baryonic matter;
at best, one might be able to provide circumstantial evidence for one or
the other of the two ideas, especially after more events will have been
observed.
  #14  
Old March 26th 16, 07:16 PM posted to sci.astro.research
Nicolaas Vroom
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Posts: 216
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

Op zondag 13 maart 2016 13:42:22 UTC+1 schreef Phillip Helbig (undress to reply):
In article , Nicolaas Vroom
writes:

http://arxiv.org/abs/1603.00464

Title: Did LIGO detect dark matter?


The interesting part about the article is that nowhere they mention
the words baryonic versus nonbaryonic. Instead what they use are the
concepts dark matter (7x) versus luminous matter (3x).
This are typical a human based concepts and IMO should not be used.
In a certain sense because we can not see BH's, by definition
we should call BH: dark-matter-hole's


These days, dark-matter almost universally (pun, as always, intended)
means non-baryonic matter.

I fully agree. However this has nothing to do with BH's. The problem
is I find the name BH's rather misleading. The issue is that what
Ligo detect is that there are very small objects with relative large masses.

Due to the no-hair theorem, we cannot say
whether these black holes formed from baryonic or non-baryonic matter;

The no-hair theorem as far as I understand makes certain claims
about three parameters of BH's and nothing related to baryonic versus
non-baryonic matter.
See: https://en.wikipedia.org/wiki/No-hair_theorem
That means the no-hair theorem cannot be used in this context.
To find an answer the first step is to answer a related question:
Is our Sun baryonic or non-baryonic?
If the answer is baryonic than the most logical answer is
that BH's are also baryonic.
That does not mean that small BH's like discovered by LIGO could
not solely be made from non-baryonic matter. In fact in the disc of
a galaxy there could be millions of these small BH's which could
be used to explain the missing matter in a Galaxy based on its
Galaxy Rotation curve.

That being the case we should expect also BH mergers within our Galaxy.

Nicolaas Vroom
http://users.pandora.be/nicvroom/

[Mod. note: apologies for the delay in posting this and the next few
submissions due to technical issues with the news server. -- mjh]
  #15  
Old March 26th 16, 07:57 PM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

In article , Nicolaas Vroom
writes:

http://arxiv.org/abs/1603.00464

Title: Did LIGO detect dark matter?

The interesting part about the article is that nowhere they mention
the words baryonic versus nonbaryonic. Instead what they use are the
concepts dark matter (7x) versus luminous matter (3x).
This are typical a human based concepts and IMO should not be used.
In a certain sense because we can not see BH's, by definition
we should call BH: dark-matter-hole's


These days, dark-matter almost universally (pun, as always, intended)
means non-baryonic matter.

I fully agree. However this has nothing to do with BH's. The problem
is I find the name BH's rather misleading. The issue is that what
Ligo detect is that there are very small objects with relative large masses.


There is absolutely no doubt at all that the recent LIGO detection was
of two merging black holes.

Due to the no-hair theorem, we cannot say
whether these black holes formed from baryonic or non-baryonic matter;

The no-hair theorem as far as I understand makes certain claims
about three parameters of BH's and nothing related to baryonic versus
non-baryonic matter.
See: https://en.wikipedia.org/wiki/No-hair_theorem
That means the no-hair theorem cannot be used in this context.


Sure it can. It says that a black hole has three properties: mass,
spin, and charge. From that one can conclude that it is impossible to
say whether it was built from baryonic or non-baryonic matter.
  #16  
Old March 29th 16, 08:03 AM posted to sci.astro.research
Robert L. Oldershaw
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Posts: 617
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

On Saturday, March 26, 2016 at 3:57:35 PM UTC-4, Phillip Helbig (undress to reply) wrote:

There is absolutely no doubt at all that the recent LIGO detection was
of two merging black holes.


There is a brand new paper: http://arxiv.org/abs/1603.08338 on the
subjects of Primordial Black Holes as candidates for the merger that
led to LIGO's detection of gravitational waves, and of PBHs as dark
matter candidates.

Clearly not the last word on these subjects, but interesting.

RLO http://ww3.amherst.edu/~rloldershaw
  #17  
Old March 30th 16, 10:30 PM posted to sci.astro.research
Nicolaas Vroom
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Posts: 216
Default Did LIGO Detect Dark Matter? - New paper on arxiv.org

Op zaterdag 26 maart 2016 20:57:35 UTC+1 schreef Phillip Helbig:
In article , Nicolaas Vroom
writes:

I fully agree. However this has nothing to do with BH's. The problem
is I find the name BH's rather misleading. The issue is that what Ligo
detect is that there are very small objects with relative large masses.


There is absolutely no doubt at all that the recent LIGO detection was
of two merging black holes.


An iteresting document to read is: http://arxiv.org/abs/1602.02444
"Binary Black Hole Mergers from Globular Clusters: Masses, Merger Rates,
and the Impact of Stellar Evolution"
1)At page 4 we read: "These prescriptions, describe the amount of material
that falls back onto the newly-formed compact object for neutrino-driven
and convection-enhanced supernovae."
2)At page 6 we read: "The blue and black points show each binary ejected
after a strong encounter with a single star, with the blue points
indicating binaries that will merge within 12Gyr. "
3)At page 7 we read: " With a relationship between the cluster parameters
and the semi-major axes of the binaries it ejects, we can show how cluster
dynamics determines the inspiral times of BBHs once they are ejected from
the cluster."
4)At page 7 we read: "What is immediately striking is that the median
inspiral time appears to decrease with increasing binary mass, in contrast
to the scaling derived in equation (10).
This is primarily due to the in
uence of the cluster itself: "
5)At page 7 we read: "As the BHs are ejected, the cluster expands and loses
mass, increasing Rh=MGC and significantly increasing the inspiral time of
the lower-mass binaries ejected at late times. "
6) At page 12 we read: "These 25 BHs are the result of repeated stellar
mergers early in the evolutionary history of the cluster.
These collisions are primarily the mergers of massive giant and
main-sequence stars during binary-single and binary-binary encounters,
with a smaller number resulting from direct collisions of single stars."

My understanding from Globular Clusters is that the most common thing
that can happen "inside" such a GC is that single stars are ejected
from the GC. The next is a Binary etc. However as soon when they are
ejected they become lonely (sets of) objects in empty space.
Remark 5 is interesting considering the opposite:
When a binary collects mass, the binary contracts and inspiral time
increases.
The issue is what is the most probably physical phenomena that causes
such an inspiralling of a binary BH. IMO remark 6.
It is tricky to use the Peters equation(36) as an explanation(See page 7)

For readers interesting in my simulation of a BH merger read this;
http://users.telenet.be/nicvroom/VB%...0operation.htm

Nicolaas Vroom
 




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