The rapid burster and its type II burst profiles.
Stella, L.; van Paradijs, J.; van der Klis, M.; Lewin, W. H. G.; Lubin, L. M.; Tan, J.; Penninx, W.; Damen, E.
United States, Netherlands
Abstract
Type-II bursts with durations ranging from about 2 to about 680 seconds are examined to study burst-peak fluxes, burst intervals, integrated energies, and luminosities associated with MXB 1730-335, the Rapid Burster. The data regarding the bursts are compared to develop general correlations between burst variables, and some general characteristics of the neutron star are theorized. As the bursts increase in duration, the flat top of the bursts increases and the number of oscillations during burst decay increase in a limited manner. Strong correlations are observed between bolometric peak fluxes, burst fluxes, and average persistent fluxes. The radiation during a type-II burst is considered to come from a photosphere with a larger radius for higher burst-accretion rates. The observational characteristics of the blackbody radii are employed to derive the magnetic dipole field-strength of the star and source zone of the bursts. Explanations are given for the spectrum of the persistent emission and the observational characteristics of the persistent emission in relation to the bursts.