2000/06/30 by Mariano Méndez, Mariano Mendez, M. van der Klis +2 · 1 citation
Physics and Astronomy · #Accretion (finance) #Amplitude #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Diagram #Optics #Physics #Pulsars and Gravitational Waves Research #Quasi periodic #Statistics #X-ray #astro-ph
paper · pdf · doi:10.1086/323486
Submitted to ApJ.(7 pages; 9 figures)
arxiv created 2001/07/25 · openalex publication_date 2001/11/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the kilohertz quasi-periodic oscillations (kHz QPOs) in the low-mass X-ray binaries 4U 1728 [34, 4U 1608[52, and Aql X-1. Each source traces out a set of nearly parallel tracks in a frequency versus X-ray count rate diagram. We nd that between two of these tracks, for similar QPO frequency, the 260 keV source count rate can di er by up to a factor of D4, whereas at the same time the rms amplitude of the kHz QPOs is only a factor of D1.1 di erent. We also nd that, for 4U 1608[52 and Aql X-1, the rms spectrum of the kHz QPOs does not depend upon which track the source occupies in the frequency versus X-ray count rate diagram. Our results for 4U 1728[34, 4U 1608[52, and Aql X-1 are inconsistent with simple "" extra source of X-rays scenarios for the parallel tracks, such as those in which the properties of the kHz QPOs are determined only by the mass accretion rate through the disk, whereas X-ray count rate also depends upon other sources of energy that do not a ect the QPOs.