Observations of Type I Bursts from Neutron Stars

Abstract

Observations of Type I X-ray bursts have long been taken as evidence that the sources are neutron stars. Black body models approximate the spectral data and imply a suddenly heated neutron star cooling over characteristic times of seconds to minutes. The phenomena are convincingly explained in terms of nuclear burning of accreted gas on neutron stars with low mass companion stars. Prospects are promising that detailed theory and data from RXTE and future missions will lead to better determinations of important physical parameters (neutron star mass and radius, composition of the accreting gas, distance of the source). Among the variety of bursts observed, there are probably representatives of different kinds of explosive burning. RXTE's discovery of a 2.5 ms persistent coherent period from one Type I burster has now linked bursters indisputably to the epitome of a neutron star, a fast spinning magnetic compact object. Oscillations in some bursts had already been thought to arise from the neutron stars' rotations. Detailed observations of these oscillations are touchstones of how the explosive bursts originate and progress, as well as independent measures of the neutron star parameters.Comment: 10 pages, 4 figures, to appear in "Cosmic Explosions, Proceedings of the 10th October Astrophysics in Maryland, AIP Conf. Proceedings 522, ed. S. S. Holt & W. W. Zhang, (AIP: Woodbury, N. Y.), 200