The phase of the radio and X-ray pulses of PSR B1937+21

Abstract

We present timing and spectral results of PSR B1937+21, the fastest known millisecond pulsar ( ms), observed with RXTE. The pulse profile, detected up to ~20 keV, shows a double peak with the main component much stronger than the other. The peak phase separation is and the pulsed spectrum over the energy range 2–25 keV is well described by a power law with a photon index equal to . We find that the X-ray pulses are closely aligned in phase with the giant pulses observed in the radio band. This results suggest that giant radio pulses and X-ray pulses originate in the same region of the magnetosphere due to a high and fluctuating electron density that occasionally emits coherently in the radio band. The X-ray events, however, do not show any clustering in time indicating that no X-ray flares are produced.