Analysis of a scorpius X-1 X-ray spectrum obtained with cooled silicon (Li) detectors

Journal Article · Thu Apr 15 00:00:00 EST 1976 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154310· OSTI ID:7347438

Laros, J G; Singer, S

An X-ray spectrum of Scorpius X-1 over the 0.5-20 keV range was obtained using cooled silicon (Li) detectors during a rocket flight in May of 1971. Thin windows, high efficiency, and approx.300 eV energy resolution resulted in a spectrum only slightly modified by the detector system above approx.1 keV. Statistics were also good, with over 5 x 10/sup 4/ source counts and a negligible background rate. An acceptable fit to the data could not be obtained using optically thin thermal models. However, a simple model which accounts for electron scattering and free-free absorption in an assumed uniform, fully ionized plasma was considerably more successful. In terms of this model the X-ray emission is from a plasma at 3 x 10/sup 7/ K surrounded by cooler and less dense plasma which scatters the X-ray photons an average of 320 times. The conceptual simplicity of the model notwithstanding, several interesting conclusions regarding previous interpretations of the Sco X-1 spectrum can be reached: (1) Prior estimates of the important source parameters: e.g., temperature, density, and physical extent: may be in error due to the usually unallowed-for scattering effects in the X-ray spectrum and the attempt to describe the entire Sco X-1 spectrum as due to a single emission region. (2) X-ray spectral variability may be caused by changes in source thickness rather than changes in temperature. (3) Since nearly every X-ray appears to have been scattered several hundred times before escaping the source, and since the energy change per scattering is approx.10 percent, any X-ray line flux should be practically unobservable. (AIP)

• Research Organization: University of California, Los Alamos Scientific Laboratory
• OSTI ID: 7347438
• Journal Information: Astrophys. J.; (United States), Vol. 205:2
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC X-RAY SOURCES
X-RAY SPECTRA
BREMSSTRAHLUNG
ELECTRONS
ENERGY RESOLUTION
PHOTONS
SCATTERING
COSMIC RAY SOURCES
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
MASSLESS PARTICLES
RADIATIONS
RESOLUTION
SPECTRA
640103* - Astrophysics & Cosmology- Quasi-Stellar
Radio
& X-Ray Sources- (-1987)