Hard X-Ray Observation of Scorpius X-1
Abstract
Results are presented of a study of the region containing the galactic source Scorpius X - 1 performed on May 17, 1989, in the energy range 15-160 keV. The search for high-energy quasi-periodic oscillations (QPOs) and LF noise, even though affected by limited statistics due to the weakness of the source in the hard X-ray range, was negative at a level of not more than 18.8 percent on a bin of 1 Hz in the range 3-10 Hz for QPOs, and at a level of not more than 11.7 percent for LFN in the bin 0-1 Hz. The present data set the first upper limit above 20 keV on the fraction of photons showing QPOs and LFN at high energy. This observation also establishes an upper limit 10 times lower than the previously reported hard tail for energies greater than 60 keV. The search for fast pulsations yielded a negative result, setting an upper limit to the pulsed fraction between 4.4 and 12.3 percent, depending on the assumed duty cycle, which confirms the nonmagnetized nature of the compact object in the binary system.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1992
- DOI:
- 10.1086/171051
- Bibcode:
- 1992ApJ...386..710U
- Keywords:
-
- Stellar Oscillations;
- Stellar Spectra;
- X Ray Stars;
- Balloon-Borne Instruments;
- Power Spectra;
- Proportional Counters;
- Spectrum Analysis;
- Astrophysics;
- STARS: INDIVIDUAL CONSTELLATION NAME: SCORPIUS X-1;
- STARS: OSCILLATIONS;
- X-RAYS: STARS