star pdf file

marginally more sensitive than BATSE for E(sub p) greater than 100 keV, but significantly more sensitive for E(sub p) less
than 100 keV. Because of its small field-of-view and low energy sensitivity, the FREGATE on HETE-2 is surprisingly
sensitive. Both the WFC on BeppoSAX and the WXM on HETE-2 are/were sensitive for low E(sub p). As expected, the GBM
on GLAST will be less sensitive than BATSE, while EXIST will be significantly more sensitive than Swift. The BeppoSAX
GRBM was less sensitive that the WFC, particularly at low E(sub p).
Author
Gamma Ray Bursts; Sensitivity; Detectors; Astrophysics; Spaceborne Telescopes
20030022796 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Effects of Resonance in Quasi-Periodic Oscillators of Neutron Star Binaries
Titarchuk, Lev; White, Nicholas E., Technical Monitor; Astrophysical Journal; October 10, 2002; Volume 578, pp. L71-L74;
In English; Copyright; Avail: Other Sources
Using a large quantity of Rossi X-Ray Timing Explorer data presented in the literature, I offer a detailed investigation into
the accuracy of the quasi-periodic oscillation (QPO) frequency determination. The QPO phenomenon seen in X-ray binaries
is possibly a result of the resonance of the intrinsic (eigen) oscillations and harmonic driving forces of the system. I show that
the resonances, in the presence of the damping of oscillations, occur at frequencies that are systematically and randomly
shifted with respect to the eigenfrequencies of the system. The shift value strongly depends on the damping rate that is
measured by the half-width of the QPO feature. Taking into account this effect, I analyze the QPO data for four Z sources,
Scorpius X-I, GX 340+0, GX 5-1, and GX 17+2, and two atoll sources, 4U 1728-34 and 4U 0614+09. The transition-layer
model (TLM) predicts the existence of the invariant quantity delta, an inclination angle of the magnetospheric axis with
respect to the normal to the disk. I calculate delta and the error bars of delta using the resonance shift, and I find that the
inferred delta-values are consistent with constants for these four Z sources, in which horizontal-branch oscillation and
kilohertz frequencies have been detected and correctly identified. It is shown that the inferred delta are in the range between
5.5 deg and 6.5 deg. I conclude that the TLM seems to be compatible with the data.
Author
Resonance; Oscillations; Neutron Stars; X Ray Binaries; Accretion Disks
20030022797 NASA Goddard Space Flight Center, Greenbelt, MD, USA
The Long-term Light Curves of X-ray Binaries Contain Simultaneous Periodic and Random Components
White, Nicholas E., Technical Monitor; Boyd, Patricia T.; Smale, Alan P.; [2002]; 19 pp.; In English; Copyright; Avail: CASI;
A03, Hardcopy
LMC X-3 and Cyg X-2 show large amplitude X-ray fluctuations that have been attributed to a warped accretion disk. Cyg
X-3 displays high amplitude, apparently non-periodic oscillations. We reanalyze these systems using RXTE ASM data and
time-frequency decomposition techniques. We find that the long-term variations in Cyg X-2 can be completely characterized
by excursions whose durations are integer multiples of the orbital period, including one essentially identical to the reported
’period‘ of 78 days. Cyg X-3 can be characterized in terms of integer multiples of a 71-day fundamental period unrelated to
the 4.8 day orbital period, but suggestively close to the approximately equal to greater than 60 day reported precession period
of the relativistic jet inferred from recent radio observations. The long-term excursions of LMC X-3 are related to each other
by rational fractions, suggesting the characteristic time scale is 10.594 days, shorter than any observed excursion to date. We
explore the phase space evolution of the light curves using a natural embedding and find that all three systems possess two
rotation centers that organize the phase space trajectories, one of low luminosity and the other of high luminosity. The
implications of this repeatable behavior on generic models of accretion disk dynamics and mass transfer variability are
explored.
Author
X Ray Binaries; Astrophysics; Light Curve; Random Processes; X Ray Astronomy; Variations
20030023598 Liege Univ., Belgium
An X-ray Investigation of the NGC 346 Field in the SMC (2): The Field Population
Naze, Y.; Hartwell, J. M.; Stevens, I. R.; Manfroid, J.; Marchenko, S.; Corcoran, M. F.; Moffat, A. F. J.; Skalkowski, G.;
[2003]; 28 pp.; In English; Original contains black and white illustrations
Contract(s)/Grant(s): SSTC-P4/05; SSTC-P5/36; Copyright; Avail: CASI; A03, Hardcopy
We present results from a Chandra observation of the NGC 346 cluster, which is the ionizing source of N66, the most
luminous HII region and the largest star formation region in the SMC. In the first part of this investigation, we have analysed
124