Radio-quiet neutron star Radio-quiet neutron star A radio-quiet neutron star is a neutron star that does not seem to emit radio emissions, but is still visible to Earth through electromagnetic radiation at other parts of the spectrum, particularly x-rays and gamma rays. Most detected neutron stars are pulsars, and emit radio-frequency electromagnetic radiation. About 700 radio pulsars are listed in the Princeton catalog, and all but one emit radio waves at the 400 MHz and 1400 MHz frequencies. That exception is Geminga, which is radio quiet at frequencies above 100 MHz, but is a strong emitter of X-rays and gamma rays. In all,
POlarization Emission of Millimeter Activity at the Sun of observing at 45 and 90 GHz comes from the necessity to determine the "upturn" frequency in the so-called "THz events": if the main radiation mechanism is synchrotron radiation from accelerated electrons emitting at chromospheric or coronal heights, it is expected a spectrum with a long and descending logarithmic tail towards millimeter wavelengths. In some cases this classical ("textbook") shape is broken and an "upturn" or "spectral reversion" is observed. Since the reversion or "upturn" frequency has been estimated around 50 to 100 GHz for the observed cases, the importance of POEMAS is justified. POlarization Emission of Millimeter Activity at