Pulsar with a period of rotation of 44 minutes?
Pulsar's pulse comes from their spin contorting the magnetic field lines. When they slow down, they lose energy, and at some point they don't have enough to create XRays.
https://www.britannica.com/science/pulsar
https://en.m.wikipedia.org/wiki/Magnetar#Description
They are both forms of neutron stars, which average around 20km but are the densest objects known to man. Fun fact, one sugar cube of their material would weigh about as much as a mountain (https://imagine.gsfc.nasa.gov/science/objects/neutron_stars1...).
Only in the sense that black holes don't have finite densities.
Well, not quite, because that analogy misses ten orders of magnitude of density difference. That just hurts my brain.
Magnetars are a whole other level of eldritch madness. The energy density of their magnetic fields is ten thousand times the density of lead.
Let that sink in for a minute.
The vacuum around a magnetar contains so much energy in the magnetic field alone that thanks to the E=mc² conversion ratio between energy and mass it has a "mass density" that is the direct equivalent to every single atomic bomb on the planet blowing up all at once and the released energy of all of that getting packed into a cubic centimeter.
Perhaps ironically, what instills in me this sense of existential dread are supervoids, more than any massively destructive structure.
I can't really explain why, but something about the idea of a incomprehensibly vast nothingness really rubs me in the wrong way.
I mean, the radius of Boötes Void is 330M light years across. I can't fathom that amount of nothing. A photon enters the Boötes void, and if it travels through its center it will take more than half a billion years to reach the other side.
In a sense it's the same thing when I think of the end of the universe. There's a comfort in thinking of a great collapse. A sense of finality, like a board game being put back in the box. In the other hand, the possibility of a heat death is absolutely dreadful. Just a never ending lingering darkness with white dwarfs slowly fading into black. No ending, no great boom, no blaze of glory.