Intensity and Source State Dependence of the Quasi-periodic Oscillations in Scorpius X-1
Abstract
Quasi-periodic oscillations (QPO) at 6 Hz were discovered from EXOSAT observations of Sco X-1 in its quiescent state by Middleditch and Priedhorsky. The authors report here on the properties of the QPO seen in earlier EXOSAT observations of Sco X-1. During these observations QPO were also detected when Sco X-1 was in an active state, in ≡20 minute dips between flares and prior to a transition to an extended quiescent state; in these cases QPO frequency varied between 10 and 20 Hz and was strongly correlated with source intensity. The transition between an active and a quiescent state was marked by variations in QPO frequency between 6 and 16 Hz which occurred on time scales of several minutes, with no intensity correlation. The authors present an oscillating thick disc obscuration model to explain the observed QPO and X-ray spectral behavior from Sco X-1.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1987
- DOI:
- 10.1086/165210
- Bibcode:
- 1987ApJ...316..411V
- Keywords:
-
- Satellite Observation;
- Stellar Oscillations;
- X Ray Binaries;
- Exosat Satellite;
- Power Spectra;
- Stellar Models;
- X Ray Spectra;
- Astrophysics;
- STARS: INDIVIDUAL CONSTELLATION NAME: SCORPIUS X-1;
- STARS: PULSATION;
- X-RAYS: BINARIES