Co-location of normal matter and dark matter

The non-neutrino component of dark matter, interacting only
gravitationally with normal matter, should occupy the same locations as
normal matter on large scales (clusters of galaxies, unless it is
extremely hot). Down to what distance scale might this correlation
hold? (Putting it another way, how close are dark and normal matter to
thermal equilbrium with each other?) For example, if one could shove
the Sun aside would it leave behind a dark matter counterpart, perhaps
of roughly similar mass? How about an asteroid?

If dark matter had much lower density than normal matter, the
counterpart dark body might extend far beyond that of the normal matter
body, in which case it could be detected by an abrupt change in the
motion of a test mass (a departing spacecraft, say).

Dear Richard Schumacher:

"Richard Schumacher" wrote in message
...
The non-neutrino component of dark matter, interacting only
gravitationally with normal matter, should occupy the same locations as
normal matter on large scales (clusters of galaxies, unless it is
extremely hot).

But not necessarily with the same distribution. Dark Matter is proposed to
not even interfere with itself... namely friction.

Down to what distance scale might this correlation
hold? (Putting it another way, how close are dark and normal matter to
thermal equilbrium with each other?)

For your parenthetic question, they of need have no correlation with each
other thermally. The two types of matter cannot transmit heat via
radiation (requiring photons, hence the name Dark), nor via conduction
(also requiring photons).

For example, if one could shove
the Sun aside would it leave behind a dark matter counterpart, perhaps
of roughly similar mass? How about an asteroid?

Better still, if Shoemaker-Levy were shadowed by Dark Matter, the Dark
Matter would have proceeded on through Jupiter... since atmospheric and
lithospheric friction would not apply.

The distribution of Dark Matter appears to not have it be *here*. It
appears to be near the rims of spiral galaxies, and some scattered
distribution across intercluster space (I think).

If dark matter had much lower density than normal matter, the
counterpart dark body might extend far beyond that of the normal matter
body, in which case it could be detected by an abrupt change in the
motion of a test mass (a departing spacecraft, say).

No such anomalous motion has been seen with Cassini, and was seen at
different "r" with three (four?) earlier probes.

If Dark Matter actually shadowed each bit of matter, then it could not fit
the requirements for Dark Matter. Additionally, if it did shadow normal
matter perfectly, then we would simply have attributed too much
contribution to normal matter, requiring a further Dark^2 Matter (TM). ;)

David A. Smith

Richard Schumacher wrote:

The non-neutrino component of dark matter, interacting only
gravitationally with normal matter, should occupy the same locations as
normal matter on large scales (clusters of galaxies, unless it is
extremely hot). Down to what distance scale might this correlation
hold? (Putting it another way, how close are dark and normal matter to
thermal equilbrium with each other?) For example, if one could shove
the Sun aside would it leave behind a dark matter counterpart, perhaps
of roughly similar mass? How about an asteroid?

If dark matter had much lower density than normal matter, the
counterpart dark body might extend far beyond that of the normal matter
body, in which case it could be detected by an abrupt change in the
motion of a test mass (a departing spacecraft, say).

Particle Dark Matter: Evidence, Candidates and Constraints
http://arxiv.org/abs/hep-ph/0404175

"Richard Schumacher" wrote in message
...
| The non-neutrino component of dark matter, interacting only
| gravitationally with normal matter, should occupy the same locations as
| normal matter on large scales (clusters of galaxies, unless it is
| extremely hot). Down to what distance scale might this correlation
| hold? (Putting it another way, how close are dark and normal matter to
| thermal equilbrium with each other?) For example, if one could shove
| the Sun aside would it leave behind a dark matter counterpart, perhaps
| of roughly similar mass? How about an asteroid?

Does the Sun have unaccounted mass? I don't think so.

| If dark matter had much lower density than normal matter, the
| counterpart dark body might extend far beyond that of the normal matter
| body, in which case it could be detected by an abrupt change in the
| motion of a test mass (a departing spacecraft, say).

I would think the presence of matter definitely alters the vacuum
equilibrium extending quite far away from it. But that would make any
effects very diluted as far as dark matter being a Sarfatti-like exotic
vacuum object. However, I have a suspicion that dark matter is probably
more like "partially-created" real matter.

FrediFizzx

Richard Schumacher wrote:

The non-neutrino component of dark matter, interacting only
gravitationally with normal matter, should occupy the same locations as
normal matter on large scales (clusters of galaxies, unless it is
extremely hot).

Hey git, with no EM interactions it cannot cool from the Big Bang. It
can only be gravitationally loosely bound, re SUSY neutralinos.

Down to what distance scale might this correlation
hold? (Putting it another way, how close are dark and normal matter to
thermal equilbrium with each other?) For example, if one could shove
the Sun aside would it leave behind a dark matter counterpart, perhaps
of roughly similar mass? How about an asteroid?

If dark matter had much lower density than normal matter, the
counterpart dark body might extend far beyond that of the normal matter
body, in which case it could be detected by an abrupt change in the
motion of a test mass (a departing spacecraft, say).

Ddi you transcribe the aural output of whoopie cushion?

--
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http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!

"RS" == Richard Schumacher writes:

RS The non-neutrino component of dark matter, interacting only
RS gravitationally with normal matter, should occupy the same
RS locations as normal matter on large scales (clusters of galaxies,
RS unless it is extremely hot). Down to what distance scale might
RS this correlation hold? (Putting it another way, how close are
RS dark and normal matter to thermal equilbrium with each other?)
RS For example, if one could shove the Sun aside would it leave
RS behind a dark matter counterpart, perhaps of roughly similar mass?
RS How about an asteroid?

I've posted a couple of times about the distribution of dark matter
within the solar system. You'd have to check Google, but IIRC the
total amount of dark matter in the solar system is less than the mass
of Uranus.

More recently, I've seen a couple of papers on astro-ph that indicate
the need for dark matter in the disk of the Galaxy in the solar
neighborhood is essentially going away. In other words, one can
account for the gravitational potential of the disk in the solar
neighborhood with the observed matter. This would suggest that the
size scale on which dark matter becomes important is somewhere between
a Galactic disk and a cluster of galaxies.

Also, there have been some estimates of the amount of dark matter in
the Sun and Earth. Various dark matter candidates (specifically
WIMPs) can accumulate in the core of either the Sun or the Earth. In
the case of the Earth, I believe they might be detectable by an excess
of neutrino emission. In the case of the Sun, they would affect
nucleosynthesis. I don't remember the limits off the top of my head,
but I believe that they are fairly stringent.

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In article ,
Richard Schumacher writes:
The non-neutrino component of dark matter, interacting only
gravitationally with normal matter, should occupy the same locations as
normal matter on large scales (clusters of galaxies, unless it is
extremely hot). Down to what distance scale might this correlation
hold?

I think the conventional view for the Milky Way, for example, is that
the dark matter is distributed approximately as the halo, whereas the
luminous matter is distributed in the familiar bulge and disk. (Bart
Bok used to speak of "the bigger and better Galaxy," referring to the
inferred massive halo.) This view ought to be checkable by velocity
dispersions of different populations, but I'm not familiar with this
area.

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Cambridge, MA 02138 USA
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