Gravitational Scalar & Redshift Distortion

In article ,
Nicolaas Vroom writes:
In short you need more matter in order to calculate a flat rotation curve.
One solution is to add more matter in the disc.
A different one is to add more matter in the halo.

All correct. The two solutions cannot be distinguished by rotation
curves alone.

This extra matter is supposed to be nonbaryonic matter.

One candidate used to be very old (and therefore cool) white dwarf
stars. I'm not sure where that hypothesis stands today. I've also
seen neutral hydrogen mentioned for some galaxies but am not sure how
important it is overall. My impression is that nonbaryonic matter is
probably the leading candidate today, but I don't think anyone would
be terribly surprised if dark baryons are important.

As a result of the CMB radiation and WMAP 85% of all matter in the
universe should be nonbaryonic (15% baryonic).

The WMAP recipe was 4.6% baryons, 24% dark matter:
http://map.gsfc.nasa.gov/news/

Planck changed that a little but not much.

The problem is: if there is only baryonic matter in galaxies where
is all this nonbaryonic matter?

There is actually another problem: about half the baryons are
themselves unaccounted for, though there was a paper a year or so ago
suggesting that most or all of the missing baryons are in hot intra-
cluster gas.

The standard view of the nonbaryonic matter comes from simulations,
which find the matter clumped but not so clumpy as the visible
matter. No one thinks today's simulations are the final word, but
the overall picture seems reasonable. In particular, there are
several experiments looking for (nonbaryonic) WIMPs locally and near
the Galactic center. So far there is no clear success, but upper
limits are still above predictions of some popular models. (I think
some models are now ruled out, but I am not an expert.)

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Op dinsdag 4 februari 2014 13:15:23 UTC+1 schreef Steve Willner:
In article ,

Nicolaas Vroom writes:

This extra matter is supposed to be nonbaryonic matter.

One candidate used to be very old (and therefore cool) white dwarf
stars. I'm not sure where that hypothesis stands today. I've also
seen neutral hydrogen mentioned for some galaxies but am not sure how
important it is overall. My impression is that nonbaryonic matter is
probably the leading candidate today, but I don't think anyone would
be terribly surprised if dark baryons are important.

My impression is that almost none of the scientists who study our galaxy
and the local universe clearly indicate when they use the word
dark matter what they mean.

IMO mostly they silently mean dark baryons. Gas, White dwarfs, Brown
Dwarfs and recently also small black holes. See for example:
http://blackholes.stardate.org/objec...p?p=NG-300-X-1

As a result of the CMB radiation and WMAP 85% of all matter in the
universe should be nonbaryonic (15% baryonic).

The WMAP recipe was 4.6% baryons, 24% dark matter:
http://map.gsfc.nasa.gov/news/

This document does not indicate what dark matter is.

The problem is: if there is only baryonic matter in galaxies where
is all this nonbaryonic matter?

There is actually another problem: about half the baryons are
themselves unaccounted for, though there was a paper a year or so ago
suggesting that most or all of the missing baryons are in hot intra-
cluster gas.

See:
http://users.telenet.be/nicvroom/fri...20age.htm#Ref1
See document 6

The standard view of the nonbaryonic matter comes from simulations,
which find the matter clumped but not so clumpy as the visible
matter.
N body simulations are relatif simple.
To start from a type of fluid (gas) and include the chemical reactions
to transfer gas to objects is extremely difficult.
The biggests problem is in the details specific if certain internal
reactions are rather speculatif and difficult to observe and to test.

No one thinks today's simulations are the final word, but
the overall picture seems reasonable. In particular, there are
several experiments looking for (nonbaryonic) WIMPs locally and near
the Galactic center.
Within our solar system there is no missing matter problem, that means
when WMIPS are detected within our solar system it can not directly
be used for galaxies to explain flat rotation curves.

etc. but I am not an expert.)
Your comments are highly appreciated.

Nicolaas Vroom

Le 06/02/2014 18:48, Nicolaas Vroom a écrit :
No one thinks today's simulations are the final word, but
the overall picture seems reasonable. In particular, there are
several experiments looking for (nonbaryonic) WIMPs locally and near
the Galactic center.
Within our solar system there is no missing matter problem, that means
when WMIPS are detected within our solar system it can not directly
be used for galaxies to explain flat rotation curves.


http://www.newscientist.com/article/...l#.UvPy4nnEiIk

GPS satellites suggest Earth is heavy with dark matter

Dark matter is thought to make up about 80 per cent of the universe's
matter, but little else is known about it, including its distribution in
the solar system. Hints that the stuff might surround Earth come from
observations of space probes, several of which changed their speeds in
unexpected ways as they flew past Earth. In 2009, Steve Adler of the
Institute of Advanced Studies in Princeton, New Jersey, showed how dark
matter bound by Earth's gravity could explain these anomalies.

http://arxiv.org/pdf/0805.2895v4.pdf

jacob navia wrote:
http://arxiv.org/pdf/0805.2895v4.pdf

This paper suggests a dark-matter explanation for the "flyby anomoly",
the reported anomolous velocity change of various interplanetary
spacecraft during Earth flybys.

However, later analysis showed that the "anomoly" is probably explained
by a transverse Doppler shift which wasn't taken into account in the
original data analysis. See arXiv:0809.1888 for details.

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Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA
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In article ,
Nicolaas Vroom writes:
My impression is that almost none of the scientists who study our galaxy
and the local universe clearly indicate when they use the word
dark matter what they mean.

I haven't noticed that, but you are probably right. The concordance
model is well known, and meaning in a specific paper may have to be
derived from context.

IMO mostly they silently mean dark baryons.

I suspect they usually mean non-baryonic dark matter, which is, as
you write:
As a result of the CMB radiation and WMAP 85% of all matter in the
universe should be nonbaryonic (15% baryonic).

(and I see I misunderstood your statement. Baryons are indeed, as
you wrote, 15% of _matter_ but only about 5% of the total energy
content of the Universe.)

http://map.gsfc.nasa.gov/news/
This document does not indicate what dark matter is.

It indicates the baryonic and non-baryonic fractions. At least half
of the baryons are probably now identified. The non-baryonic matter
is still a mystery, though the most popular guess is WIMPs. There
are some constraints on what these could be but so far nothing
approaching an identification.

N body simulations are relatif simple.

In principle. Actually doing them is hard.

To start from a type of fluid (gas) and include the chemical reactions
to transfer gas to objects is extremely difficult.

True. And that's not even the kind of simulation I meant. The dark
matter simulations are far simpler, using only gravity (and I think
only Newtonian gravity) plus initial conditions and constraints
derived from cosmology. And they are still really hard. The problem
is that the relevant size scales range all the way from a few parsecs
(maybe less!) up to the size of the Universe, and that wide a range
is impossible to calculate in detail with existing computers.

Simulation of baryon physics is far harder still. That doesn't stop
people from trying, but they have to put in lots of simplifying
assumptions. In particular, there is no general theory of star
formation, so the simulations have to put in something like "when gas
gets to a certain density, it magically forms stars." That doesn't
mean the simulation results are useless, but no one thinks baryon
physics is understood.

Within our solar system there is no missing matter problem, that means
when WMIPS are detected within our solar system it can not directly
be used for galaxies to explain flat rotation curves.

The WIMPs don't contribute significant mass within our solar system,
but that doesn't mean they are absent entirely. Direct detection of
WIMPs would give particle masses, for example, and perhaps typical
energies. How exactly this might affect cosmology I don't know.

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Help keep our newsgroup healthy; please don't feed the trolls.
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Op zondag 9 februari 2014 10:17:01 UTC+1 schreef Jonathan Thornburg
jacob navia wrote:

http://arxiv.org/pdf/0805.2895v4.pdf

This paper suggests a dark-matter explanation for the "flyby anomoly",
the reported anomolous velocity change of various interplanetary
spacecraft during Earth flybys.

However, later analysis showed that the "anomoly" is probably explained
by a transverse Doppler shift which wasn't taken into account in the
original data analysis. See arXiv:0809.1888 for details.

For a more recent state of the art document read this:
http://arxiv.org/abs/1112.5426
"Modeling the flyby anomalies with dark matter scattering:
update with additional data and further predictions"
by Stephen L.Adler

My interpretation reading the documents is that the amounts
(density) of (nonbaryonic) dark matter involved is very small.
At least much smaller to explain flat galaxy rotation
curves based on dark baryonic matter.

There is also an other issue: when there is a "large" amount
of nonbaryonic matter around the sun this could also
be used to explain the precession of the perihelion of the
planet Mercury.

Nicolaas Vroom

In article , Nicolaas Vroom
writes:

There is also an other issue: when there is a "large" amount
of nonbaryonic matter around the sun this could also
be used to explain the precession of the perihelion of the
planet Mercury.

But since it is explained by GR, this would require one to abandon GR as
well. But where does evidence for nonbaryonic matter come from? Mostly
from cosmology, based on GR.

Op woensdag 12 februari 2014 08:09:11 UTC+1 schreef Phillip Helbig
In article , Nicolaas Vroom

writes:



There is also an other issue: when there is a "large" amount
of nonbaryonic matter around the sun this could also
be used to explain the precession of the perihelion of the
planet Mercury.

But since it is explained by GR, this would require one to abandon GR as
well.

I agree. This means that there is (almost) no nonbaryonic matter around the sun.
This could mean that there is no nonbaryonic matter around any star
and also not in the disc.

But where does evidence for nonbaryonic matter come from? Mostly
from cosmology, based on GR.

IMO the evidence only comes from WMAP data ie CMB radiation.
When you study the literature for our "local" universe almost no one
discusses the issue of non baryonic matter.

Nicolaas Vroom

In article , Nicolaas Vroom
writes:

IMO the evidence only comes from WMAP data ie CMB radiation.
When you study the literature for our "local" universe almost no one
discusses the issue of non baryonic matter.

Look up "baryon fraction in clusters". There is a regime between the
local environment (Local Group, say) and the observable universe. There
is evidence from galaxy clusters, for example, that there is
non-baryonic matter.

In article ,
Nicolaas Vroom writes:
when there is a "large" amount
of nonbaryonic matter around the sun this could also
be used to explain the precession of the perihelion of the
planet Mercury.

The perihelion of Mars should also precess. (These two planets have
the most eccentric orbits.) _Probably_ more significant, different
planets should give different values for "solar mass" (technically
the Gaussian gravitational constant) because larger orbits would
enclose more mass.

Perhaps the OP or someone else could calculate the magnitude of these
effects if the local nonbaryonic matter density is equal to the
Concordance Model cosmic value.

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