That's actually a profound question. The usual answer would be just 1, EM radiation of all wavelengths. That's what is relevant for the OP's question.

But do gravity waves, if they exist, constitute "radiation"? I tend to think the term "radiation" is reserved for EM and for radioactivity. A blast of neutrinos doesn't count, in my opinion.

 

I remember first reading about CMB in Scientific American in the 60’s. It was suppose to be an evenly distributed flux thru-out the universe. It has been the main “evidence” of the big bang theory. It has been classified as a remnant radiation......left over from an old action or process.
Over the years the resolution has really improved.......and of course......it’s not an even flux......far from it. If you look closely at the universe map, you will see.....like all IR radiation....it comes from matter. If you look closely...it is a band of frequencies. It peaks at the hydrogen molecule because that is the preponderance of matter. The CMB is just as dynamic as light is. All atomic matter emits IR. Play with an IR camera. The CMB is a map of matter in the universe.
The problem with the Thread Starter’s question.....is the definition of temperature. Why do we need more than one way to look at what temperature is? Is it the same for a astronomer, a chemist, bridge engineer or a quantum physicist? Is it that scale thing again? You know.....laws working differently at different scales? Is it really a measure of kinetic energy? If a particle has no kinetic energy....does it have no temp?
Does modern science know what temperature is?
I know......it’s a quantum effect.
Temperature is the average amplitude, phase and frequency of the electric and magnetic fields in the area.
This causes particles to change their flicker rate....not their vibration rate. Other forces can change the flicker rate. Light, nearby particles, position and other strong fields can exchange energy thru the flicker rate........it’s how it all related.

 

It can shoot up to thousands of degrees depending on the proximity to a star or a planet. But surprisingly, if you walk through the space, it wouldn't freeze you to death ever. Because of the constant electromagnetic energy freely flowing.

 

Just temperature is secondary, also how much energy the medium can deliver is important.

In high altitudes like the thermosphere, you have high temperature, but its close to vacuum.

 

Good point, takao.