How does the electromagnetic force influence a galaxy (if at all)?

[Blinked]

Like what are the chances that dark matter can be described with electromagnetism instead?

 

[Orodruin]

Like what are the chances that dark matter can be described with electromagnetism instead?

None.

 

[Vanadium 50]

Like what are the chances that dark matter can be described with electromagnetism instead?

Like none.

 

[lomidrevo]

Have you tried to read some basic available info about dark matter?

Immediately in the fist paragraph of the wiki article you can find the following sentence:

Dark matter is called dark because it does not appear to interact with observable electromagnetic radiation, such as light, and is thus invisible to the entire electromagnetic spectrum, making it extremely difficult to detect using usual astronomical equipment.

I confess that this statement might have it's own flaws, but it manages to answer your question. If not satisfied with this one, just the second resource found by google (search for "dark matter" naturally) says:

Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot. In fact, researchers have been able to infer the existence of dark matter only from the gravitational effect it seems to have on visible matter.

source: https://home.cern/science/physics/dark-matter

 

[alantheastronomer]

Like what are the chances that dark matter can be described with electromagnetism instead?

You seem to be asking, "can the effects attributable to "dark matter" be due to some sort of electromagnetic process instead?", am I right? A reasonable assumption, however very tricky observations of the splitting of spectral lines finds that the magnetic fields of galaxies are very, very weak, so unfortunately this idea doesn't seem to be supported by observations.

 

[stefan r]

Spiral galaxies usually have a magnetic field of around 1 nanoTesla. Compare to Earth with around 30 nanoTesla.

The magnetic field will effect a charged particle with the Lorentz force.

Like what are the chances that dark matter can be described with electromagnetism instead?

None. The motion described by dark matter is measured by the light from stars. Bulky objects like planets and stars do not hold much electric charge per unit of mass.
Consider what happens with electrostatic cling. You can see and feel this with films like plastic or with hair. The static with a low mass/high surface material is easily large enough to defy gravity. So your hair can stand on end when it is dry and the piece of plastic wrap does not appear to want to go into the trash. Your skin is also carrying the electric charge. You know this because you can get a shock anywhere. The force from the electrostatic is not enough to lift you in any noticeable way. [a very precise scale could measure it]

The effects of electricity and magnetism will be much stronger on pieces of dust than they are on asteroids or comets. The orbits of stars or planets will be mostly unaffected once they have formed. Dark matter is effecting the gas, dust, and stars in the same way. Variations in the concentration of dark matter do not correlate with variations in the strength of galactic or stellar magnetic fields.

Magnetic fields can change the orientation of interstellar dust grains. That causes some polarity effects. Magnetic fields play a significant role in star formation. They likely effect planet formation too. Magnetic fields play a major role the jets in active galactic nuclei. The formation of quasars and their jets may be a significant factor in galaxies becoming spirals.