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Thomson opacity (split from I finally found an accurate article on the speed of universal expansion)

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6 hours ago, Mordred said:

This is nothing like redshift and nothing like the cosmological constant.

Now you might think 1 % is miniscule at z=1 however that becomes a major factor if you extend the curve you graphed to z=1100.

You wouldn't even be able to measure the CMB at that range.

That's what I've tried to say several times now

Thomson opacity is not a substitute for "dark energy", just a (slight) correction to the best-fit benchmark cosmology parameters

and, no, you cannot extend Thomson opacity beyond the beginning of reionization 6<z<11

Prior to that epoch, there were no free electrons and no Thomson opacity

CMB polarization measurements have placed an upper bound on the maximum Thomson opacity at 0.06 or so, perfectly consistent with these calculations:

 

image.png.629ef8989848d173e6b003d08524b659.png

Given that the neutral fraction becomes increasingly appreciable beyond z>6, one might expect that actual optical depth to increase more or less like follows, again completely consistent with maximums from measured CMB polarization:

image.png.95c00e4df17229c7e16c9ab55560313a.png

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Posted (edited)

Good so you agree on the requirement for free electrons. You also agree that from here to Z=6 approximately there are insufficient free electrons for Thompson scatterrings.

 However I should note that any point between electroweak symmetry breaking and the surface of last scatterrings there will be.

Hence the cosmological dark age. The mean free path of photons are less that 10^{-32} metres. 

Now you know Thompson scatterrings only really applies to low wavelengths of light x-rays and gamma rays will involve Compton scattering. (The breakdown of the nonrelativistic limit).

So why would you feel a correction is required for z=1 and z=2 when you also know Thompson scatterrings doesn't apply to all spectrums of light ? And you know we use spectronomy to determine luminosity ? (Luminosity being one of the more common tools used) Tully Fisher, Faber Jackson relations both use it)

Ie the luminosity distance relationship as mentioned before we do rely on redshift alone. Also have angular diameter distance and various forms of parralax.

Lastly given polarity aspects of scatterring we are able to determine when scatterrings are occuring. The graphs in those links demonstrate that.

Please don't take anything I state in offense. I present challenges to consider. A good robust model must overcome challenges. That is the truth behind the scientific methodology. You must weigh every piece of evidence.

Edited by Mordred

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On 3/8/2020 at 9:27 PM, Mordred said:

from here to Z=6 approximately there are insufficient free electrons for Thompson scatterrings

Please read ISM & IGM by Ryden & Pogge, I'm sure their accessible style will clarify these concepts for you

Again, that's completely backwards

The IGM is fully ionized = all electrons free from both H,He from z=0 to z=6-11

Remember your cosmic history

  1. Big Bang (fully ionized)
  2. expansion & cooling
  3. Recombination (neutralization at z~1100)
  4. dark ages (fully neutral)
  5. Reionization (z~11)
  6. fully ionized IGM
  7. present epoch (z=0)

A basic lowest order linearization scheme reveals that accounting for Thomson opacity in the "benchmark cosmology" (0.27,0.73) results in slight adjustments to:

Omega (Dark-)Matter / Omega Lambda / Omega Radiation -- very slight effects, reducing radiation in favor of matter would be consistent with neutrinos have rest-masses m>1e-4 eV and so not being relativistic at T~2-3K (they would drop out of the radiation term & be reinserted into the (Dark-)Matter term)

+0.0044 +0.0001 -0.0005

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4 hours ago, TEFLing said:

 

The IGM is fully ionized = all electrons free from both H,He from z=0 to z=6-11

 

How have we detected atomic and molecular signals from a fully ionized medium?

"THE first clear positive evidence for the existence of inter-galactic atomic neutral hydrogen was advanced in 1966 by Koehler and Robinson"

https://www.nature.com/articles/220147a0

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Posted (edited)
6 hours ago, TEFLing said:

Please read ISM & IGM by Ryden & Pogge, I'm sure their accessible style will clarify these concepts for you

Again, that's completely backwards

The IGM is fully ionized = all electrons free from both H,He from z=0 to z=6-11

Remember your cosmic history

  1. Big Bang (fully ionized)
  2. expansion & cooling
  3. Recombination (neutralization at z~1100)
  4. dark ages (fully neutral)
  5. Reionization (z~11)
  6. fully ionized IGM
  7. present epoch (z=0)

A basic lowest order linearization scheme reveals that accounting for Thomson opacity in the "benchmark cosmology" (0.27,0.73) results in slight adjustments to:

Omega (Dark-)Matter / Omega Lambda / Omega Radiation -- very slight effects, reducing radiation in favor of matter would be consistent with neutrinos have rest-masses m>1e-4 eV and so not being relativistic at T~2-3K (they would drop out of the radiation term & be reinserted into the (Dark-)Matter term)

+0.0044 +0.0001 -0.0005

I suggest you look into big bang nucleosynthesis starting from electroweak  symmetry breaking as the above isn't accurate. Atoms for one could not form until the temperature dropped sufficiently low enough. That occurs during the epoch of recombination. Any period before then has sufficient free electrons. If you like later on when I get a chance I will show how the Saha equations show when the loss  of free electrons will occur.

 

Edited by Mordred

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6 hours ago, TEFLing said:

reducing radiation in favor of matter would be consistent with neutrinos have rest-masses m>1e-4 eV and so not being relativistic at T~2-3K (they would drop out of the radiation term & be reinserted into the (Dark-)Matter term)

Not clear what the cosmic neutrino background has to do with anything in this context. In particular matter even at relativistic speed is very different from the massless CMBR.

The CNB dropped out of equilibrium at about BB +1sec; it has been largely undetectable since then. Its temperature is about 1.95K, another important difference from the CMBR at 2.72K.

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Posted (edited)

Just before recombination, the

baryonic matter in the universe was at a temperature where it formed a hot ionized plasma. Most of the photons in the universe interacted with electrons and protons, and could not travel significant distances without interacting with ionized particles. As a result, the universe was opaque or "foggy". Although there was light, it was not possible to see, nor can we observe that light through telescopes.

At around 370,000 years, the universe has cooled to a point where free electrons can combine with the hydrogen and helium nuclei to form neutral atoms.[43] This process is relatively fast (and faster for the helium than for the hydrogen), and is known as recombination.[44] The name is slightly inaccurate and is given for historical reasons: in fact the electrons and atomic nuclei were combining for the first time.

https://en.m.wikipedia.org/wiki/Chronology_of_the_universe

Consider the above.I would recommend you read through the chronology though the exact times are model specific so you will get numerous variations on the sequence in that link. I usually avoid wiki, however I haven't the time atm to get you a decent article. I will later on.

Consider the above.I would recommend you read through the chronology though the exact times are model specific so you will get numerous variations on the sequence in that link. I usually avoid wiki, however I haven't the time atm to get you a decent article. I will later on.

Edited by Mordred

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Posted (edited)

So as you mentioned Ryden let's use Barbera Rydens benchmark model. Introductory to Cosmology 2006 page 189. Recombination and Decoupling.

By the Way Barbera Rydens textbook was one of my favourites.

Now She starts with stating that in order to understand the CMB one must understand the transition of when ionized plasma to a gas of neutral atoms.

The first stage mentioned is the epock of recombination. Numerically the time when the number density of ions equals the number density of neutral atoms.

She then described the epoch of photon decoupling. (The time of which the photons that scatter from electrons becomes smaller than the Hubble parameter) be careful here the Hubble parameter evolves over time is much much higher in this time period. When photons decouple they cease to interact with electrons and the universe BECOMES transparent.

The surface of last scatterring being the time when the CMB photons underwent it's last scattering from an electron.

Before we go into the math she presents I would like to see if you agree with the above.

(Though to use the Saha equation it's often better to start with matter radiation equality).

We will also add the redshift values later in accordance to Rydens benchmark model methodology.

Edited by Mordred

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