A Third X-Ray Spectral Mode in Scorpius X-1: Similarities to the Other Bright Bulge Sources
Abstract
Sco X-1 normally shows two spectral/quasi-periodic oscillation (QPO) modes. In this paper, new observations of Sco X-1 are reported which show it in a third mode which is similar to the 'horizontal branch' displayed by Cyg X-2 and suggests that the Galactic bulge sources follow a common, Z-shaped spectral pattern. In this mode, the spectral hardness remains constant, the intensity decreases, and the power spectrum shows a broad noise component at about 2 Hz. In all branches, Sco X-1 shows a previously unreported noise continuum which cuts off at about 60 Hz.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1989
- DOI:
- 10.1086/167154
- Bibcode:
- 1989ApJ...337..843H
- Keywords:
-
- Galactic Bulge;
- Neutron Stars;
- Stellar Mass Accretion;
- X Ray Binaries;
- Color-Color Diagram;
- Exosat Satellite;
- Optical Thickness;
- Power Spectra;
- Spectral Bands;
- Stellar Oscillations;
- Astrophysics;
- STARS: INDIVIDUAL CONSTELLATION NAME: SCORPIUS X-1;
- X-RAYS: BINARIES