In my cosmic and atomic model (TOE) the cosmos is made up of equivalent levels across the fourth dimension of space, such that smaller units (for example, atoms) can come together and add up to constitute another higher unit (the stars) that are similar and equivalent in their structure, forces, physical laws and elements.
The stars can also add up and form other superior units, such as the supra-stars, one of which had to explode and produce our Big-bang.
But in this case, what interests us are the luminous particles, that is, those that, being very small in relation to the explosion of a unit of the higher level, get to acquire great speed, (speed of light c,) constituting themselves at sometimes disc-shaped as in galaxies, also high-energy cosmic rays, and likewise, photons.
Well, a photon is a very small disk-shaped particle made up of a large number of lower-level units, or sub-atoms.
A cosmic ray of high energy UHECR will be a particle that will be constituted by a disk of smaller units (the atoms) that circulates at the speed of light.
And a galaxy is another particle made up of smaller units, such as stars in this case.
Thus, all of them are particles that are expelled in a big explosion and acquire the speed of light c.
In the drawing you can see an indicative setting of the UHECR energy.
Of course these cosmic rays are not all the same, but of a wide range of dimensions and energies.

UHECR high-energy cosmic rays (and their component atoms), and due to their high speed, are destroyed by our atmosphere logically producing large amounts of smaller particles, mainly leptons, neutrinos, protons, and of course light.

As indicated in the drawing, pulsars and quasars could be produced as a consequence of "stellar reactions", that is, when stars unite to form stellar groups (binary-double star 2, 3, 4 5. ..), and to maintain the entropy of energy of the new group, they emit a large amount of energy in the form of all kinds of particles.