Map reveals strange cosmos.

Op dinsdag 5 februari 2013 21:40:48 UTC+1 schreef Phillip Helbig---undress to reply het volgende:
In article , Nicolaas Vroom
writes:

What is worthwhile is to calculate the Power Spectrum from
the surface of the Sun and from the surface of our Earth.

Can you explain why? Consider also that the data were taken while the
satellite revolved (with the Earth) around the Sun.

For the Sun what I propose is the measurement of the radiation (temperatures)
of the surface of the Sun.
For the Earth it is the height above and below sea level.
(Of course you can also try Earth surface temperatures)
My prediction is that the three power spectra will look rather similar.

My understanding is, that the calculation Power Spectrum based on the data
in http://map.gsfc.nasa.gov/media/121238/index.html
is purely a mathematical operation. That means it does not matter
if the colors represent temperatures, pressures or flows the power spectrum
calculated will be the same using the same values.
In short the calculation should not take any physics into account.

Nicolaas Vroom.

In article , Nicolaas Vroom
writes:

No. The hot spot is simply some observable feature. One could just as
well consider a cold spot. This is not unique to the CMB; it applies to
all angular-size distances in cosmology.

This whole issue is discussed in more detail he
http://users.telenet.be/nicvroom/M.%...s.htm#hotspots

It should be mentioned that the observed sphere of photons is not a
physical object, it has no distance. The observed sphere is something
like the night sky. The same with observable Universe.

Not really. The CMB is not a hard surface, but one can speak of a
distance to an optical depth of 1 or whatever, just like with the "
surface" of the Sun.

This is an article from 2003 which uses both the words decoupled and
recombination. IMO we should use the word decoupling era, because that
was what, assumed, has happened. Recombination reflects going back in
time, which did not happen.

Two different concepts. "Decoupling" refers to matter becoming
transparent to radiation. "Recombination" is something different; it
refers to electrons and nuclei combining to form atoms. The two are
related but not simultaneous. (As you note, "recombination" is a
misnomer. Here, it should be "combination". Generally, in physics,
when this happens, it happens to something which was previously ionized,
hence REcombination.)

What I want to understand is how are those vertical lines calculated?
Why are they not evenly spaced?

This is probably due to the graph being presented with a different axis
to that which was used internally, i.e. angle and multipole moment.

When you test all the images in that same document this is the same:
Always one color is zero, always one value is 255.
When you consider this spherical image this is not true: Max Tegmark's
Home. The picture is blurred. One color that is added is black to make
it look round. That means the original data is modified. Why?

Just to give it the appearance of 3-dimensionality.

When you study the following you can see that the "equator" consists
of 4096 pixels. The question is what is measured.
I do not know the details but I expect that the number of photons
for each pixel is counted for a fixed time period. However that is not
enough you have to do that for each pixel for different frequencies
or wavelengths. The (raw) value for each pixel is than set
with the frequency with the highest count.
However I expect that that is not the end.
I expect that a certain smoothing is taken into account. That means
that the final frequency is calculated based on a couple of surrounding
pixels.
Based on the final frequency you can calculate a color and the temperature
for each picture.

CMB observations are made with radio-astronomy techniques, i.e. there is
no counting of photons. Several frequencies are measured.

In article , Nicolaas Vroom
writes:

In article , Nicolaas Vroom
writes:

What is worthwhile is to calculate the Power Spectrum from
the surface of the Sun and from the surface of our Earth.

Can you explain why? Consider also that the data were taken while the
satellite revolved (with the Earth) around the Sun.

For the Sun what I propose is the measurement of the radiation (temperatures)
of the surface of the Sun.
For the Earth it is the height above and below sea level.
(Of course you can also try Earth surface temperatures)
My prediction is that the three power spectra will look rather similar.

They don't.

My understanding is, that the calculation Power Spectrum based on the data
in http://map.gsfc.nasa.gov/media/121238/index.html
is purely a mathematical operation. That means it does not matter
if the colors represent temperatures, pressures or flows the power spectrum
calculated will be the same using the same values.

Yes, but the Sun looks different than the CMB, so the power spectrum
will look different.

In short the calculation should not take any physics into account.

Yes, but that doesn't mean that everything looks the same.

On 2/5/2013 3:28 PM, Nicolaas Vroom wrote:
...
And, for others who might want to play with it, is
there a link to the raw data? (The ASCII file with
the numbers that give rise to these images?)

For raw data goto: http://map.gsfc.nasa.gov/media/121238/index.html

There may be a misunderstanding here, but I don't
see any (link to) data on that page. Also if I surf
around over the links given, no data ever come within
reach..

Each value is a combination of 4 parameters:
alpha (=255), red, green and blue.
However for some reason NASA used tricky colors.
When you go to: http://space.mit.edu/home/tegmark/saskmap.html
they use for the color scheme from -100 mK to 100 mK the following scheme:
Red --- X 0 0 0 X X
Green - 0 0 X X X 0
Blue -- X X X 0 0 0

I get the impression that you are trying to obtain
data here by reverse-engineering some visualized
representation of the data.

That may be the only way if the original data set
is not publicly available.

X stands for the value 255.
The colors are from left to right: magenta, blue, cyan, green, yellow, and red.
In between magenta and blue there are 254 colors:
(255,0,255) next (254,0,255) next (253,0,255) finally (1,0,255) and (0,0,255)
In between all blue and cyan there are also 254 colors etc.
This scheme is simple and allows you to calculate the Temperature
in a straight forward manner.

You mean: backwards interpreting a color picture
that is created by someone else from the actual
data set. (As far as I can follow you. Correct me
if I'm wrong!)

The Nasa scheme is much more complicated:
The scheme is from -200 mK to 200 mK .
The color code starting with the coldest is:
(33,6 98) (32,7,96) (32,9,95) (32,9,91) (32,10,86) (32,11,77) (32,12,75) (27,20,65) etc
Maybe there are more intermediate values used.

Well, if they want to keep the data secret, they
should of course use a complicated color scheme.
If not, then my question is still: where are the
data? (Simple black-on-white ascii text will do!)

[Mod. note: of course the COBE and WMAP data are not secret. The first
hit on Googling for 'COBE data' should get you somewhere useful. The
WMAP data are at
http://lambda.gsfc.nasa.gov/product/...m_products.cfm . I am one
of many non-WMAP-affiliated scientists who has written papers using
the WMAP data --mjh]

--
Jos

In article ,
Phillip Helbig---undress to reply writes:
Two different concepts. "Decoupling" refers to matter becoming
transparent to radiation. "Recombination" is something different; it
refers to electrons and nuclei combining to form atoms. The two are
related but not simultaneous.

There's a nomenclature problem in that "decoupling" is sometimes used
to refer to moment when matter and radiation no longer have the same
energy density. That's some time in the first few minutes after the
Big Bang. I personally prefer to stick to that usage, but I'm
probably in the minority of astronomers in that view. The takeaway
point is that if you use 'decoupling', you better be sure context
makes clear which one you mean.

I don't see how recombination and decoupling (in the second sense)
can be other than simultaneous. The transformation from plasma to
normal atoms is what made the universe transparent.

(As you note, "recombination" is a
misnomer. Here, it should be "combination". Generally, in physics,
when this happens, it happens to something which was previously ionized,
hence REcombination.)

I think you meant "previously neutral." In normal physics, neutral
atoms are ionized, and then they recombine. The _process_ of going
from separate nuclei+electrons to neutral atoms is called
"recombination," and it's natural to use the same word (even though
it's a misnomer) for cosmic recombination, even though there were no
neutral atoms prior to then.

CMB observations are made with radio-astronomy techniques, i.e. there is
no counting of photons.

Some are made that way. Others, e.g., DIRBE, use photo-detectors,
and still others use bolometers. (DIRBE had two bolometer channels.)
None of this matters once the data are calibrated into physical
surface brightness units. Because the CMB spectrum is an exact
blackbody, the surface brightness units can be expressed as a
temperature. That last conversion may fail where the spectrum has
been affected by foregrounds, e.g., Sunyaev-Zeldovich clusters.

The really tricky part is subtracting non-cosmological foregrounds:
the Zodiacal light, Galactic sources, and bright local galaxies. I
believe that's the dominant uncertainty in the whole-sky data, though
not necessarily in smaller regions (higher multipoles).

There's a huge amount of information at
http://lambda.gsfc.nasa.gov/
I think all the raw and processed data from both COBE and WMAP are
there, but I haven't checked for certain.

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

Op donderdag 7 februari 2013 00:27:16 UTC+1 schreef Jos Bergervoet het volgende:
On 2/5/2013 3:28 PM, Nicolaas Vroom wrote:
...
And, for others who might want to play with it, is
there a link to the raw data? (The ASCII file with
the numbers that give rise to these images?)

For raw data goto: http://map.gsfc.nasa.gov/media/121238/index.html
There may be a misunderstanding here, but I don't
see any (link to) data on that page.

The information is on the right hand side:
The url for the largest display is at:
http://map.gsfc.nasa.gov/media/12123...r_moll4096.png
I use both Corel Photo Paint and Visual Studio 2010 to process the data
and to calculate the temperatures.

I get the impression that you are trying to obtain
data here by reverse-engineering some visualized
representation of the data.

That is correct. I calculate the temperatures based on the color
values red, green and blue. I wish there was an easier way.

Well, if they want to keep the data secret, they
should of course use a complicated color scheme.
If not, then my question is still: where are the
data? (Simple black-on-white ascii text will do!)

[Mod. note: of course the COBE and WMAP data are not secret. The first
hit on Googling for 'COBE data' should get you somewhere useful. The
WMAP data are at
http://lambda.gsfc.nasa.gov/product/...m_products.cfm . I am one
of many non-WMAP-affiliated scientists who has written papers using
the WMAP data --mjh]

In the file:
http://lambda.gsfc.nasa.gov/product/...t_spec_get.cfm
shows the calculated power spectrum using LCDM model
(To read the .tar.gz files I used 7 Zip)
In the text is written:
# Column 5 = portion of column3 error attributed to cosmic variance,
# assuming the best-fit LCDM model
My impression is that if you want to retrieve temperature data
you have to study FITS and HEALPIX.
For example:
http://lambda.gsfc.nasa.gov/common/f..._9yr_V_v5.fits

[Mod. note: correct. You will not get anything scientifically useful
by messing around with PNG files -- mjh]

Nicolaas Vroom

In article , Steve Willner
writes:

Phillip Helbig---undress to reply writes:
Two different concepts. "Decoupling" refers to matter becoming
transparent to radiation. "Recombination" is something different; it
refers to electrons and nuclei combining to form atoms. The two are
related but not simultaneous.

There's a nomenclature problem in that "decoupling" is sometimes used
to refer to moment when matter and radiation no longer have the same
energy density. That's some time in the first few minutes after the
Big Bang. I personally prefer to stick to that usage, but I'm
probably in the minority of astronomers in that view. The takeaway
point is that if you use 'decoupling', you better be sure context
makes clear which one you mean.

Right. There are three things which happen around the same time:
combination (usually called recombination), matter becoming transparent
to radiation, and the energy density of radiation dropping below that of
matter. The three are related, but distinct processes. As you say, the
nomenclature can be confusing here.

(As you note, "recombination" is a
misnomer. Here, it should be "combination". Generally, in physics,
when this happens, it happens to something which was previously ionized,
hence REcombination.)

I think you meant "previously neutral."

No, I meant "previously ionized". That is, a neutral sustance is
ionized then it recombines. So, for it to REcombine, it had to have
been ionized previously. However, in the scenario here, before (re)
combination there was the ionized state, but before the ionized state
there was no neutral state, hence it can combine, but not recombine.

In normal physics, neutral
atoms are ionized, and then they recombine. The _process_ of going
from separate nuclei+electrons to neutral atoms is called
"recombination," and it's natural to use the same word (even though
it's a misnomer) for cosmic recombination, even though there were no
neutral atoms prior to then.

Right.

CMB observations are made with radio-astronomy techniques, i.e. there is
no counting of photons.

Some are made that way. Others, e.g., DIRBE, use photo-detectors,
and still others use bolometers. (DIRBE had two bolometer channels.)

Right. IIRC, Planck has "traditional" receivers for the lower
frequencies and bolometers for the higher ones, but nothing like a CCD
such as those used for higher frequencies (e.g. optical).

In article ,
Phillip Helbig---undress to reply writes:
There are three things which happen around the same time:
combination (usually called recombination), matter becoming transparent
to radiation, and the energy density of radiation dropping below that of
matter. The three are related, but distinct processes. As you say, the
nomenclature can be confusing here.

I thought there was a time when nucleons decoupled from gamma rays,
but apparently "decoupling" is not used for that. There is "neutrino
decoupling," which occurs about 1 s after the Big Bang. Dark matter
decoupling should also occur, though when depends on the properties
of the dark matter.

About the best reference I could find quickly is
http://www.oxfordreference.com/view/...98608585-e-101

No, I meant "previously ionized". That is, a neutral sustance is
ionized then it recombines.

The second sentence is the point I was making about the terminology.
We don't disagree on the physics or even very much on the
terminology.

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

In article , Steve Willner
writes:

There are three things which happen around the same time:
combination (usually called recombination), matter becoming transparent
to radiation, and the energy density of radiation dropping below that of
matter. The three are related, but distinct processes. As you say, the
nomenclature can be confusing here.

I thought there was a time when nucleons decoupled from gamma rays,
but apparently "decoupling" is not used for that. There is "neutrino
decoupling," which occurs about 1 s after the Big Bang. Dark matter
decoupling should also occur, though when depends on the properties
of the dark matter.

In the wider sense, everything decouples at some point, associated with
some (postulated) symmetry breaking in some GUT.

Op maandag 11 februari 2013 22:34:02 UTC+1 schreef Steve Willner het volgende:
In article ,
Phillip Helbig---undress to reply writes:
There are three things which happen around the same time:
combination (usually called recombination), matter becoming transparent
to radiation, and the energy density of radiation dropping below that of
matter. The three are related, but distinct processes. As you say, the
nomenclature can be confusing here.

The most confusing part is a clear description of the processes that
took place where and when. (with an indication how sure we are)

About the best reference I could find quickly is
http://www.oxfordreference.com/view/...98608585-e-101
1) This document claims:
" Eventually, however, with the plasma at around 3000K, even these
photons become too feeble to prevent atoms forming.
With no free electrons left, photons have nothing to interact with and
travel freely through the Universe - they are said to have decoupled etc".
The question is what means freely? Does this imply undisturbed?

2) My understanding of radiation (photons) is that they are created when
electrons move from a higher band to a lower band.
3) At page 287 of the Book "Astronomy and Cosmology" by Fred Hoyle 1975
below Figure 6.21 is written:
"Because of absorption and reemission and because of scattering inside
a (proto) star, radiation leaks out of the interior only very slowly"
At page 288 below Figure 6.22 is written:
When the temperature near the surface of a newly forming star falls below
4000 K the gases are no longer able to block the escape of radiation
in an effective way"
4) From the document http://arxiv.org/abs/1212.5225 (9 Year Bennett)
At page 83 is written:
"5.3.7.3. ILC Considerations
The primary difficulty with any method of extracting the CMB from the data
is determining how much of the temperature in each pixel is foreground
and how much is CMB. The data only constrain the sum of these two, and
we must make other assumptions in order to separate them.
The ILC specifically assumes that the CMB has a black body spectrum"

IMO what they should have added in #4 is:
How much from foreground, how much from intermediate (proto stars) and
how much from CMB.

Op vrijdag 8 februari 2013 11:41:48 UTC+1 schreef Phillip Helbig---undress to reply het volgende:
In article ,

CMB observations are made with radio-astronomy techniques, i.e. there is
no counting of photons.

Some are made that way. Others, e.g., DIRBE, use photo-detectors,
and still others use bolometers. (DIRBE had two bolometer channels.)

Right. IIRC, Planck has "traditional" receivers for the lower
frequencies and bolometers for the higher ones, but nothing like a CCD
such as those used for higher frequencies (e.g. optical).

When you study page 14 of document in #4 above you will see that they use
the word intensity a lot. This indirectly IMO implies photon count.
The document also shows that (only?) 5 frequency bands are measured
(K, Ka, Q, V and W) which indirectly implies that not all
CMB photons are not taken into account

Nicolaas Vroom