Polarization and coherence properties of stellar radiation.

[carlosbelcech]

Hello, I opening this post for to debate the properties of stellar radiation. I interested to know if there are measurements of the coherence degree of stellar sources and if exits some as "a polarization degree". I was studying the ponderomotive effect as a possible cause of redshift. I understand this effect such as is explained in the attachment. Two cuasi-colinear beams of coherent and plane polarized light (laser) with nearing frequencies can produces a interference pattern with a certain group velocity. This velocity can be arbitrarily slow, until to reach the thermal velocity of electrons of a hipotetic intergalactic plasma. If one pattern to coincide in velocity and direction with one electron, there are certain probability of produces the energy transference from higher energetic photon to the lowest one, as is explained in the attachment. Until now, I can get a redshift in base to this phenomenon, with a "number of events of transference" independent of the wavelength and this do not like me.
I guess that this phenomenon could explain the z dependent time dilation.
But, the question that I want to dilucide is if the stellar radiation could produce this patterns, still in a randomic way. I understand that it is necessary a certain degree of polarization and coherence.
Astronomical redshift from ponderomotive effect.docx (1).pdf
kozak2018.pdf

[RedshiftDrift]

Stellar radiation is slightly polarized. However, radiation emitted by matter in magnetic fields has a higher degree of polarization e.g. sun spots via Zeeman effect, cyclotron radiation via magnetic field, the CMB via "gravitational waves" (according to LCDM) or magnetic fields (according to a non-cosmological origin of the CMB). Scattering off dust particles also polarizes radiation. Longer coherence lengths are seen in specific objects like astronomical masers (methane, hydrogen, synchrotron) and Fast Radio Bursts, but other sources have a very short coherent length comparable to about a wavelength (as for any blackbody source).

Reading your notes and comments in the attached paper, you are about at the stage I was when I wrote "Optical forces as a redshift mechanism: the “Spectral Transfer Redshift”" I believe you are on the right track!

[carlosbelcech]

"The ponderomotive potential must be described without the "time-average" approximation"
R: ok, I understand that this is a future task. You don't did it yet.

"The energy transfer heating the IGM is very low. However, the energy transfer cooling the IGM can only result from electron-electron collisions via bremsstrahlung, which is even lower. The electrons must collide frequently and at high velocity (i.e. be hot) to lose the energy acquired by the photon-redshift"
R: Ok, I understand that electrons don't has a way for to dissipate the heat. Or, its cooling is very poor. I agree. There are estimations of the magnetic field in the IGM. I do not remember the paper. But, I think that is possible to start of these estimations to calculate the thermal velocity of electrons. Faster electron velocities implies higher differences between $\omega_1$ and $\omega_2$, nothing else.

"Then all these interactions can be summed up to describe any coherence of the light waves"
R: Sorry, but either I do not understand this affirmation or I do not agree. For me, there must be short-live patterns with which the electrons interact. You say that wave trains of one-wavelenght coherence longitude coincide spontaneous and randomicly to form longer patterns. Ok, I can agree.

"The probability that a coincidence of velocity and direction occurs is small, but when the electric fields of the waves are intergated over all directions and over the entire distribution of electron velocities, the result is sufficiently large to account for the cosmological redshift."
R: Yes, as there are a velocity distribution of electrons, the range of $\delta \omega= \omega_1 - \omega_2$ is wider. In my stone-age attempt I wanted to use average values. But, the range of angles must be restricted to the angular diameter of the sources. I think that the mixture of spectra of different profiles from different sources must be a secondary and almost negligible effect, on the contrary, this mixture could to alterate the profiles, the specific "signatures"of the sources.

By another hand, the transfer delay from $\omega_1$ to $\omega_2$ can explain the z dependent time dilation.

One question: Do you have a best proposal for the group velocity equation?. I want to confirm this.

[RedshiftDrift]

"...ponderomotive potential described without the "time-average"" R: ok, I understand that this is a future task. You don't did it yet.

I am working on it right now!

"all these interactions can be summed up " R: Sorry, but either I do not understand this affirmation or I do not agree. For me, there must be short-live patterns with which the electrons interact. You say that wave trains of one-wavelenght coherence longitude coincide spontaneous and randomicly to form longer patterns.

Said differently:

• wave trains of one-wavelength (short) coherence are decomposed as a sum of waves with long-coherence (>100 meters),
• each long-coherence waves $\omega_i$ and $\omega_j$ interact to produce the redshift,
• all these interactions can be summed up to get redshift with short coherence light.

One question: Do you have a best proposal for the group velocity equation?. I want to confirm this.

The group velocity is the same equation as the usual wave propagation in an electron plasma.

[carlosbelcech]

Ok, at this point I tell you that I was thinking at the moment of write the post in "Redshift models".

1. In relation to coherence degree of stellar radiation. I had searched some papers and had readed about the coherence properties of blackbody radiation, with a coherence length assigned of one wavelength. The generation of this radiation is attributed to independent oscillators that emit spontaneously with a quantified energy, where the stimulated emission is discarded. What happen if the stimulated emission is subvaluated?. We has speculated that in semiconductors the stimulated emission is present and can to produce appreciable effects in the optic properties. In the surface or in the atmosphere of Sun (chromosphere?), where are produced the photons that leave the star. There not stimulated emission?, Inclusive at high scale? In the stellar atmosphere (and surface), surely the atoms are highly ionized with its "electron populations" totally inverted, like in a Laser. The knock of a photon on an excited atom, Would not to produce a chain reaction of stimulated de-excitations in the surrounding gas?. These chain reactions, Would not generate something like swarms of coherent photons?. Is this a non-sense? Something like coherent wave fronts or coherent wave clusterings with determinate sizes, with its coherence length and coherence duration. The sunlight would is made with these flocks of coherent photons embedded and hidden in the whole of radiation. If this is so, the ponderomotive effect would conservate the coherence properties of radiation along its travel and I believe that would very difficult to detect these. The fraction "spontaneous" of radiation would be no significant. After all, we know that until free electrons can produce laser radiation. Perhaps, these hidden or non-discover properties of stellar radiation would be the unique initial assumption of the proposal that we discuss. If is verified later, would be a golazo.

2. In relation to ponderomotive effect equations, I was thinking in to approximate the excited state of free electrons in the electromagnetic field of the bichromatic pattern like a harmonic oscillator. Is to say, to consider to free electron as a confined particle in a potential well, the ground state is the free electron, when the electron to absorb a photon $h \nu$ and is excited, the oscillator step to an excited state, and later, when is knocked by the second photon $h (\nu +\delta \nu)$, return to the ground state with an energy plus $h (\delta \nu)$.

3. In relation to "coherence idea", the size of bichromatic patterns, as function of the coherence length of beams can be a (wavelength dependent) free parameter of future fits. Starting from Hubble's law or the value of H, would be possible to determine the coherence properties of radiation.
   Sorry, I have that to tell you.

[RedshiftDrift]

Thanks for sharing this, I think I understand your idea. A comment on what you write about the surface of the Sun (chromosphere).

You say "surely the atoms are highly ionized with its "electron populations" totally inverted" but inversion is not possible for the principal quantum levels of hydrogen or helium. At best hydrogen masers emit coherent radio waves and helium can lase in the infrared. But there is no laser levels in pure hydrogen or helium for visible light. Sunlight is mostly blackbody radiation and its coherence length is very short (see this paper)

[carlosbelcech]

Yes. This paper is one of the firsts that the web shown when someone searches. Is one of that I saw.
I send you other.
Do you want to say that great part of the sunlight is from accelerated ions in the plasma?. bremsstrahlung? or accelerated charge radiation of isolated ions or electrons?
It's true, as you say, either helium nor hydrogen can lase in visible light, point for you. Must be another stuff.
But, don't matter, I hope that you can to advance.
PD: I go to study photoconductivity for now, before that they throw me out. I will back if I have something interesting.

Carlos
kastner95.pdf

[RedshiftDrift]

Do you want to say that great part of the sunlight is from accelerated ions in the plasma?. bremsstrahlung? or accelerated charge radiation of isolated ions or electrons?

Yes, most of the light from the sun is produced by this incoherent process and appears as a blackbody spectrum. The spectral lines listed in the kastner95.pdf paper are emitted/absorbed by elements present in very small quantity on the sun.

[carlosbelcech]

Ok, two point for you. Do you know about the Van Cittert-Zernike theorem? I'm exploring it, it could be the salvation. I think that if you reach a solid result you should try to publish it, for example, in "Galaxies". If I can outline a paper I'll keep you informed, although my chances are close to zero.

[RedshiftDrift]

See under "Assumptions of the theorem"

Quasi-monochromatic waves
The van Cittert–Zernike theorem assumes that the source is quasi-monochromatic. ... This requirement implies that a radio astronomer must restrict signals through a bandpass filter. Because radio telescopes almost always pass the signal through a relatively narrow bandpass filter, this assumption is typically satisfied in practice.

That's why earlier, I discussed filtering

"... the electron "selects" pairs of waves that have the same phase, so effectively the electron does some filtering that increases the coherence."

I'll post the news here when my paper is published.