Some Early Results from the Rossi X-ray Timing Explorer (RXTE)

Abstract

The Rossi X-ray Timing Explorer (RXTE) was successfully launched on 1995 December 30 and has been operational since that time. Its three instruments are probing regions close to compact objects, degenerate dwarfs, neutron stars, stellar black holes and the central engines of AGN. Temporal studies with the ASM and PCA have already yielded rich results which pertain to the environs, evolution, and nature of the compact objects in galactic systems. Here I review some selected results from these instruments, as obtained by various RXTE observers. The ASM is providing detailed light curves of about 60 detected sources and has uncovered new temporal/spectral states of galactic binary systems. The bizarre behavior of the possibly very young binary system, Cir X-1, is being revealed in detail by both the ASM and the PCA. A rare high/soft state of the black-hole candidate, Cyg X-1 provides new insight into the nature of the low/high transitions in black-hole binaries. The PCA has made possible the discovery of oscillations near 1 kHz in ten low-mass X-ray binary systems. These are most probably direct indicators of the neutron-star spin in some cases and probably indirect indicators in others. Studies of microquasars have unveiled a host of new temporal phenomena which may provide links between accretion processes and the radio jets in these systems.