Cosmology Views

Explaining the Intergalactic Medium - Part 1 - Hydrogen

This is a conjecture about behaviors of hydrogen in the Intergalactic Medium (IGM).
This Part 1 is about hydrogen in the IGM. Part 2 is about calcium in the IGM.

Despite the lack of public galaxy spectra, a  few descriptions provide enough clues for  explaining the behavior of hydrogen in the IGM.

This conjecture is worthwhile, until more galaxy spectra are revealed. 

This explanation must be tentative when lacking important data.

The IGM topic is long but hopefully discussing only hydrogen is productive.

My paper titled "Clarifying Redshifts" is has the background for the significance of the IGM.

That paper concluded a red shift outside a galaxy must originate in the IGM which is in the line of sight. That papert did not attempt to explain it because the IGM was beyond the scope for that topic which focused on the Doppler effect.

The hydrogen atoms in the IGM behave differently than hydrogen outside the IGM based on observational data.

1 )
First, high red shifts are explained.

excerpt from the study of the highest red shift galaxy ( z=11.1):

Spectroscopic confirmations of very high-redshift candidates remain limited, however. The primary spectral feature accessible from the ground for these sources, the Ly-alpha line, is likely attenuated by the surrounding neutral hydrogen for all z > 6 galaxies. Therefore, despite the large number of candidates from HST imaging, only a handful of galaxies in the epoch of reionization have confirmed redshifts to date.
Given the low success rate of Ly-alpha searches, a viable alternative approach is to search for a spectroscopic confirmation of the UV continuum spectral break. This break is expected owing to the near-complete absorption of UV photons shortward of Ly-alpha by neutral hydrogen in the early universe.
(excerpt end)


The red shift z=11.1 measurement is explicitly from the Ly-alpha line because that is the emphasis here. The reference to this red shift being affected by much neutral hydrogen in the early universe clearly recognizes the redshift is caused by neutral hydrogen atoms in the IGM,  not caused by a velocity.

excerpt from a paper about galaxies with z from 9 to 10:

The identification of LBGs in the epoch of reionization makes use of the almost complete absorption of UV photons shortward of the redshifted Ly-alpha line due to a high neutral hydrogen fraction in the inter-galactic medium.
(excerpt end)

These galaxies with z from 9 to 10 have their redshift from ’hydrogen in the inter-galactic medium’ as explicitly mentioned in this paper. The redshift is known to be from the IGM, not from a velocity.

LBG is a Lyman Break galaxy

The conclusion from the consistent explanation for galaxy red shifts of z from  9 to 11.1 is:

The measured high red shift is from neutral hydrogen atoms in the IGM.


lower red shifts are explained.

many might recall this without a reference, but this is also in my "clarifying redshifts" document :

Initially by the 1930's, astronomers observed the proportional relationship between red shift and distance. This initial version of Hubble's Law was a distance metric.
This metric's validity depended on the uniformity of hydrogen in the IGM.

This observed behavior is a red shift which accumulates by hydrogen atoms in the IGM so the red shift increases by distance to the light source.

This initial observation for red shifts in the IGM matches the behavior observed with high red shifts.

The following is a possible mechanism for this observed behavior. It is impossible to duplicate the conditions of the IGM when they are unknown by being out of reach of current technology to obtain a sample or a direct measurement.

As described in my "clarifying redshifts" document,  the Doppler effect involves an energy transfer.

An absorption line is the removal of some specific amount of energy emitted by the source; this energy is transferred to the atom executing a change to a higher energy state, as defined by the element's electron configuration (which defines the required energy to absorb).

 In the case of an atom in motion, the absorption line is shifted by the proportion of the kinetic energy from the ratio of the atom's velocity to the speed of light. The energy, proportional by velocity in the direction of travel, is added to the energy being absorbed resulting in a blue shift in the line.

The energy, proportional by velocity in the direction opposite of travel, is subtracted from the energy being absorbed resulting in a red shift in the line.

From the observational history, the hydrogen atoms in the IGM perform a cumulative red shift. This means each atom executes an incremental red shift or removal of energy in the passing light.
This increment has not been determined because the red shift has been mistakenly assumed to occur in the galaxy not the IGM. Analysis of actual spectra is required to explain this incremental behavior.

This analysis also requires the measurement of the contents in the IGM which has yet to occur.

Without  the other components  in the IGM, a complete explanation of the absorption line red shift in the IGM is not possible.

An absorption line  with a blue shift means the IGM would be  adding energy to the passing light  and there is no observation of such a blue shift (in the IGM) which has been noted.

Only a small number of galaxies have a blue shift absorption line which is apparently from an atom in motion, not the IGM; all those are explained in part 2 for calcium absorption line shifts.

The conclusion of Part 1 for hydrogen absorption line red shifts:

Absorption lines for a galaxy must be ignored because they originate outside the galaxy and are not a velocity for the galaxy.

last changed 04/14/2020