Dark Matter Cross-Section

Ref: http://arxiv.org/abs/1503.07675

This reference indicates dark matter cross-section
and resultant drag characteristics
for 72 studied galactic collisions
....47 cm^2/g
The Pioneer 10 and 11 cross-sections are
....24 cm^2/g

Is the near proximity of these two values
an indication of a common drag mechanism?

In article ,
"Richard D. Saam" writes:
Ref: http://arxiv.org/abs/1503.07675
This reference indicates dark matter cross-section
and resultant drag characteristics
for 72 studied galactic collisions
...47 cm^2/g

The reference places an _upper limit_ on the cross section of
0.47 cm^2/g. As far as these data are concerned, the actual cross
section could be orders of magnitude smaller or even strictly zero.

Note also the significance with which dark matter is detected.

The Pioneer 10 and 11 cross-sections are
...24 cm^2/g

Reference? Is this also an upper limit or a claimed detection? And
where is the decimal point in the value?

Is the near proximity of these two values
an indication of a common drag mechanism?

More likely it just indicates widely different techniques end up with
similar sensitivities.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On Wednesday, April 1, 2015 at 12:46:32 PM UTC-4, Richard D. Saam wrote:
Ref: http://arxiv.org/abs/1503.07675

This reference indicates dark matter cross-section
and resultant drag characteristics
for 72 studied galactic collisions
...47 cm^2/g
The Pioneer 10 and 11 cross-sections are
...24 cm^2/g

There is no need to invoke dark matter for the Pioneer trajectory.
Indeed, the trajectory can be explained by spacecraft thermal effects,
within the measurement range.

CM

On 4/9/15 6:34 AM, Craig Markwardt wrote:
On Wednesday, April 1, 2015 at 12:46:32 PM UTC-4, Richard D. Saam wrote:
Ref: http://arxiv.org/abs/1503.07675

This reference indicates dark matter cross-section
and resultant drag characteristics
for 72 studied galactic collisions
.47 cm^2/g
The Pioneer 10 and 11 cross-sections are
.24 cm^2/g

There is no need to invoke dark matter for the Pioneer trajectory.
Indeed, the trajectory can be explained by spacecraft thermal effects,
within the measurement range.

CM

The JPL statement in regards to Pioneer spacecraft thermal effects
"no statistically significant acceleration anomaly exists."
http://arxiv.org/abs/1204.2507
is based on incomplete analysis of the data.

This JPL paper
assumes the decay for Pioneer acceleration aP

daP/dt = -k*aP model one

This fits the assumption that all aP components
are tied to the RTG half life with aP decay approaching zero with time.

A better fit to trajectory data is:

daP/dt = -k*(aP - aPinfinity) model two

Initially, the thermal emission overwhelms
the anomalous acceleration (aPinfinity)
but diminishes with time(model one)
with aP decay approaching aPinfinity with time (model two).

In as much as aPinfinity is a measure of
interstellar intergalactic space viscosity
as Pioneers exit the solar system,
then all transiting object motion
in interstellar intergalactic space would be affected
including dark matter candidates with similar cross-section to Pioneers
as per http://arxiv.org/abs/1503.07675.

Richard D Saam

[Mod. note: This post arrived at my moderation mailbox with some garbled
character encodings (various occurences of "=3D0") and line wrappings.
I have fixed these up by hand based on educated guesses as to the authors'
meanings, and rewrapped over-long lines. I hope I haven't distorted
anyone's meaning!
-- jt]

On Thursday, April 9, 2015 at 3:57:22 PM UTC-4, Richard D. Saam wrote:
On 4/9/15 6:34 AM, Craig Markwardt wrote:
On Wednesday, April 1, 2015 at 12:46:32 PM UTC-4, Richard D. Saam wrote:

....
The Pioneer 10 and 11 cross-sections are
.24 cm^2/g

There is no need to invoke dark matter for the Pioneer trajectory.
Indeed, the trajectory can be explained by spacecraft thermal effects,
within the measurement range.
....
The JPL statement in regards to Pioneer spacecraft thermal effects
"no statistically significant acceleration anomaly exists."
http://arxiv.org/abs/1204.2507
is based on incomplete analysis of the data.

This JPL paper
assumes the decay for Pioneer acceleration aP

daP/dt = -k*aP model one

This fits the assumption that all aP components
are tied to the RTG half life with aP decay approaching zero with time.

And this model is statistically consistent with the data.

A better fit to trajectory data is:

daP/dt = -k*(aP - aPinfinity) model two

Since you didn't show how it is a "better fit" it's hard to comment
in detail, but since model one is statistically consistent with the
data, aPinfinity=0 is also statistically consistent with the data.
I.e. there is no need to invoke dark matter to explain the Pioneer
trajectory.

CM

On 4/11/15 1:19 PM, Craig Markwardt wrote:

On Thursday, April 9, 2015 at 3:57:22 PM UTC-4, Richard D. Saam wrote:
On 4/9/15 6:34 AM, Craig Markwardt wrote:
On Wednesday, April 1, 2015 at 12:46:32 PM UTC-4, Richard D. Saam wrote:

The Pioneer 10 and 11 cross-sections are
.24 cm^2/g

The Pioneer 10 and 11 cross-section = (pi/4)*274^2/241,000 = .24 cm^2/g
Pioneer antenna diameter 274 cm
Pioneer mass 241,000 g
There is no need to invoke dark matter for the Pioneer trajectory.
Indeed, the trajectory can be explained by spacecraft thermal effects,
within the measurement range.
...
The JPL statement in regards to Pioneer spacecraft thermal effects
"no statistically significant acceleration anomaly exists."
http://arxiv.org/abs/1204.2507
is based on incomplete analysis of the data.

This JPL paper
assumes the decay for Pioneer acceleration aP

daP/dt = -k*aP model one

This fits the assumption that all aP components
are tied to the RTG half life with aP decay approaching zero with time.

And this model is statistically consistent with the data.

A better fit to trajectory data is:

daP/dt = -k*(aP - aPinfinity) model two

Since you didn't show how it is a "better fit" it's hard to comment
in detail, but since model one is statistically consistent with the
data, aPinfinity=0 is also statistically consistent with the data.
I.e. there is no need to invoke dark matter to explain the Pioneer
trajectory.

CM

I did post on sci.astro.research the aPinfinity analysis
9/3/13, 11:14 PM under a discussion on WIMPS.

the methodology is there with subsequent analysis indicating
for Pioneer 10
aPinfinity = 6.1 x 10^-10 m/sec^2 vs 5.9 x 10^-10 m/sec^2

For Pioneer 11 subsequent analysis to posting

aPinfinity = 7.1 x 10^-10 m/sec^2

Model two Data analysis with aPinfinity
provide a better statistical correlation
than aPinfinity = 0.

Question 1: Why wasn't model two ever discussed or used by JPL?
Why did I have to do the analysis,
piecing together available published data?
The logical need for Model two analysis seems so obvious
and its simplicity is so compelling.
Billions of dollars are being spent at CERN,
satellites such as FERMI and multi underground facilities
around the world to obtain some indication of Dark Matter.
A comparatively simple model two analysis provides a hint
or at least results that may fit some other phenomenon.
Why is JPL so closed minded about this opportunity
for scientific discovery?

Question 2: Where is the original Pioneer trajectory data?
NASA generally publishes its data. Why not in this case?

Richard D Saam

On 4/3/15 2:32 AM, Steve Willner wrote:
In article ,
"Richard D. Saam" writes:
Ref: http://arxiv.org/abs/1503.07675
This reference indicates dark matter cross-section
and resultant drag characteristics
for 72 studied galactic collisions
.47 cm^2/g

The reference places an _upper limit_ on the cross section of
0.47 cm^2/g. As far as these data are concerned, the actual cross
section could be orders of magnitude smaller or even strictly zero.

Note also the significance with which dark matter is detected.

The Pioneer 10 and 11 cross-sections are
.24 cm^2/g

Reference?
Based on published NASA Pioneer dimensional data.
The Pioneer 10 and 11 cross-section = (pi/4)*274^2/241,000 = .24 cm^2/g
Pioneer antenna diameter 274 cm
Pioneer mass 241,000 g

Is the near proximity of these two values
an indication of a common drag mechanism?

More likely it just indicates widely different techniques end up with
similar sensitivities.

Further and more likely:
If dark matter objects had similar dimensions to Pioneers
as common cross-sections would imply,
then the dark matter galactic density on the order of 10^-24 g
composed of these Pioneer sized objects
would have a mean free path or optical density
such that they would not be optically visible
under current methods.
(An accepted dark matter characteristic)

Also, the dark matter objects
cannot be in thermal equilibrium with CMBR at 2.7K
as they would radiate to a measurable level.
(Another accepted dark matter characteristic)

Since CMBR mass density
CMBR density = Stefan_constant*2.7^4*(4/c^3) ~ 1E-34 g/cc
is low relative to universe density
Universe density ~ H^2/G ~ 1E-29 g/cc
there is a possibility that dark objects are in thermal equilibrium
with the much higher universe density at
a much colder non measurably radiating temperature
defining an extremely cold hydrogen state
with Big Bang nucleosynthetic origin.

Hydrogen Dark matter nucleosynthetic origin
requires consideration of nuclear reaction rates
modified by nucleosynthetic plasma colligative properties
implied by Brookhaven National Laboratory high Z collision studies.

These ideas are contrary to the WIMP dark matter hypothesis
but since WIMPS have not been found
in any of the underground scintillation projects,
these ideas are open for further analysis.

Richard D Saam


[[Mod. note -- It has long been suggested (tongue-in-cheek) that dark
matter might be composed of back issues of The Astrophysical Journal.
[Yes, I know, I'm showing my age -- I'm using the phrase
"back issues" to refer to actual black-marks-on-paper
physical objects rather than just bits in a database
somewhere...]
However, I'm not sure if ApJ-sized lumps of baryons would be allowed
by other observational constraints.
-- jt]]