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timmdeeg

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- Is there an upper limit for the temperature of recombination (last scattering)?

The commonly called value of the temperature at recombination is 3000 K.

According to this reference the process of recombination can be described by the Saha equation:

3.1. Recombination and the formation of the CMB

Whereby 0.3 eV equals 3480 K.

Another reference:

It is mainly determined by the ionization potential of hydrogen and the baryon-to-photon ratio. ne ~ 500 cm-3 (roughly same as Galactic HII regions) Te = Tr = 2970 K = 0.26 eV

Tr = 3000 K fits well to the redshift z ~ 1100 of the CMB (according to the L-CDM model) with respect to the 2.725 K we measure it today. I wonder if there is an upper limit for Tr.

The cosmological model of Alexandre Deur claims Such fit yields H0 = 72.99 ± 0.06 km/s/Mpc, zL = 1728 ± 1

Redshift z = 1728 of the CMB would suggest that Tr is around 4700 K however. Considering plasma physics would you say that's still reasonable?

According to this reference the process of recombination can be described by the Saha equation:

3.1. Recombination and the formation of the CMB

*Recombination happens quickly (i.e., in much less than a Hubble time t ~ H-1), but is not instantaneous. The universe goes from a completely ionized state to a neutral state over a range of redshifts
z ~ 200. If we define recombination as an ionization fraction Xe = 0.1, we have that the temperature at recombination TR = 0.3 eV.*

Whereby 0.3 eV equals 3480 K.

Another reference:

It is mainly determined by the ionization potential of hydrogen and the baryon-to-photon ratio. ne ~ 500 cm-3 (roughly same as Galactic HII regions) Te = Tr = 2970 K = 0.26 eV

Tr = 3000 K fits well to the redshift z ~ 1100 of the CMB (according to the L-CDM model) with respect to the 2.725 K we measure it today. I wonder if there is an upper limit for Tr.

The cosmological model of Alexandre Deur claims Such fit yields H0 = 72.99 ± 0.06 km/s/Mpc, zL = 1728 ± 1

Redshift z = 1728 of the CMB would suggest that Tr is around 4700 K however. Considering plasma physics would you say that's still reasonable?

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