Today I learned something more about sterile neutrinos, and the latest advancement to the quest of finding them.
I was searching for something extrordinary to learn to open the blog, and here it is, what can be the most important discovery since since Quantum Mechanics.
Sterile neutrinos are supposed particles (as once were the electron neutrinos) that we don't know yet. The neutrinos we know are the products of weak interaction decay, and thus are associated with a reference lepton, .
We can try to imagine that, if unknown particles exists, they are the product of the gravitational field and/or another force that we don't know, since the other forces we know of (strong, electromagnetic and weak) are strong enough that we have the confidence to be able to see their manifestations.
The unknown particles that are purely gravitational or, even more exciting, interact with another 5th force we don't yet know, have neutral charge (otherwise will interact electromagnetically and be easy to detect), and thus the lepton decay product associated to this field is a neutrino associated to the other neutrinos by the means of oscillations that would explain irregolarities in the neutrino oscillations spectrum.
Since this neutrino is not associated to any reaction we know of, except the eventual oscillation with the ordinary neutrinos, is called sterile. For this reason a direct detection would be impossible to perform since would require a huge amount of a material unbeknown to us.
But since we are damned smart (yes we are) we figured out a way to catch the uncatchable particle that interact with an unknown particles using an unknown interaction. We have that huge amount of material, we don't known what it is and if it is, but we have it. Plenty of it, in plenty of space: the universe.
So we look in the sky in the search for everything we don't understand, and we discovered that we don't understand a good deal of it, and we call it dark matter and dark energy. Than we think of what can it be that generate this dark "stuff", and we answer ourselves that the "stuff" is "stuff we don't know, but definetly stuff". And then, always watching in the sky, analyzing data from dozens of galaxies, we detect this 3.5 keV band that can be the answer to our call for help: the signature of a 7 keV sterile neutrino decaying into photon and ordinary neutrino.
Is not the first time such a claim has been made, due to the staggering complexity of the data under analysis the results are often rejected after revision, but in the meantime let me praise how clever we are.