Engineering topics
Publications and source records attributed to vanParadijs, J. A..
The support provided under this grant covered several projects, based on observations made with the Compton Gamma Ray Observatory, particularly with the Burst And Transient Source Experiment BATSE. The results of our work were published in 23 papers, 18 Circulars of the International Astronomical Union, and one popular article. I report on these projects separately.
SGR 1806-20 turned active late 1996, and in response to this reactivation we triggered our target-of-opportunity observations. The results were extremely rewarding. We found a periodic modulation of the persistent X-ray signal, at a period of 7.47 seconds. We combined our data with similar data obtained by Dr T. Strohmayer, which confirmed the presence of the pulsations, and gave evidence for a spin down on a time scale of some 1000 years. We retrieved the pulsations in archival ASCA data, obtained in 1993 and 1995, and confirmed the long-term spin down of the neutron star in this system. The properties of SGR 1806-20 lead to the conclusion that it is a mgnetar, i.e., a neutron star with a magnetic field some 2 to 3 orders of magnitude higher than those of young radio pulsars and binary X-ray pulsars.