Neutrino Pulsar

A new hypothesis suggests that we should be able to see beams of TeV (trillion electron volt) neutrinos coming from certain pulsars in the sky. A pulsar is a rotating neutron star possessing high magnetic fields and spewing energy in a searchlight pattern, usually observed at radio wavelengths.

According to Bennett Link of Montana State University, the potent nature of a young, rapidly spinning neutron star---emitting the energy of our sun but from a surface 5 billion times smaller, and in the form of x rays---creates electric fields of fantastic strength, some 10¹⁵ volts. These fields will whip protons in the vicinity up to PeV (10¹⁵ eV) energies. When such protons collide with the x rays emanating from the star, delta particles (essentially heavy protons) can be created. When these subsequently decay energetic neutrinos are formed.

This whole production mechanism---proton acceleration, delta creation, daughter neutrino cascades---sweeps around like the radio waves normally seen from a pulsar. With the right detector, the pulsar would reveal itself through neutrinos. If such a neutron star were as far away as our sun, the Earth would receive about a million 50-TeV neutrinos per square cm per second. Actual pulsars are, of course, much further away from us.

Nevertheless, Link (link@physics.montana.edu) estimates that there are about 10 neutrino pulsars within a distance of 15,000 light years from Earth. He believes that these energetic sources might result in about 10 neutrino detections per year in a square-kilometer detector, which is about the effective size of the so-called IceCube facility being built now.

Neutrino pulsars could be the brightest continuous high-energy neutrino sources in the universe and their detection would help to bolster the idea of neutrino astronomy. (Link and Burgio, Physical Review Letters, 13 May 2005)