1999ApJ...512L..35Y -
Astrophys. J., 512, L35-L38 (1999/February-2)
The kilohertz QPO frequency and flux decrease in Aquila X-1 and the effect of soft X-ray spectral components.
YU W., LI T.P., ZHANG W. and ZHANG S.N.
Abstract (from CDS):
We report on a Rossi X-Ray Timing Explorer observation of Aquila X-1 during its outburst in 1997 March in which, immediately following a type I burst, the broadband 2-10 keV flux decreased by about 10% and the kilohertz quasi-periodic oscillation (kHz QPO) frequency decreased from 813±3 to 776±4 Hz. This change in kHz QPO frequency is much larger than expected from a simple extrapolation of a frequency-flux correlation that was established in data before the burst. Meanwhile, a very low frequency noise component in the broadband fast Fourier transform power spectra, with a fractional rms amplitude of 1.2% before the burst, ceased to exist after the burst. All these changes were accompanied by a change in the energy spectral shape. If we characterize the energy spectra with a model composed of two blackbody (BB) components and a power-law component, almost all the decrease in flux was in the two BB components. We attribute the two BB components to the contributions from a region very near the neutron star, or even from the neutron star itself, and from the accretion disk, respectively.
Abstract Copyright:
∼
Journal keyword(s):
Stars: Individual: Constellation Name: Aquila X-1 - Stars: Neutron - X-Rays: Stars
Simbad objects:
3
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:1999ApJ...512L..35Y and select 'bookmark this link' or equivalent in the popup menu