Related papers: Statistical Analysis for the Q-factor of twin kHz …
We have carried out a systematic study of the properties of the kilo-Hertz quasi-periodic oscillations (QPO) observed in the X-ray emission of the neutron star low-mass X-ray binary 4U1608-52, using archival data obtained with the Rossi…
We report on a comprehensive analysis of the kilohertz (above 300 Hz) quasi-periodic oscillations (kHz QPOs) detected from the neutron star low-mass X-ray binary 4U0614+09 with the Rossi X-ray Timing Explorer (RXTE). With a much larger data…
We report the discovery of a kilohertz quasi-periodic oscillation (kHz QPO) in the low-mass X-ray binary (LMXB) 2S 0918-549. The kHz QPO has a frequency of 1156+-9 Hz, a FWHM of 70+-20 Hz, and a fractional rms amplitude of 18%+-2%. We also…
I summarize the available RXTE data of the 4 low-mass X-ray binaries (LMXBs) and Atoll sources Aql X-1, 4U 1728-34, 4U 1608-52, and 4U 1636-53. I concentrate on the relation between the frequencies of the quasi-periodic oscillations at…
We discovered two simultaneous kHz quasi-periodic oscillations (QPOs) in the bright low-mass X-ray binary and Z source GX 5-1 with the Rossi X-ray Timing Explorer. In the X-ray color-color and hardness-intensity diagram a clear Z track is…
In this paper, we improve the previous work on the MHD Alfven wave oscillation model for the neutron star (NS) kHz quasi-periodic oscillations (QPOs), and compare the model with the updated twin kHz QPO data. For the 17 NS X-ray sources…
We report the discovery of kHz quasi periodic oscillations (QPOs) in three Rossi X-ray Timing Explorer observations of the low mass X-ray binary (LMXB) XTE J1701-407. In one of the observations we detect a kHz QPO with a characteristic…
It is known that the Z and atoll sources are two typical types of neutron-star sources in low mass X-ray binaries (LMXBs), which present very different Q-$\nu$ relations of lower kHz QPOs. We propose that the Z and atoll sources are two…
Strong, coherent, quasi-periodic brightness oscillations (QPOs) with frequencies ranging from about 300 Hz to 1200 Hz have been discovered with the Rossi X-ray Timing Explorer in the X-ray emission from some fifteen neutron stars in…
A long discussion has been devoted to the issue of clustering of the kHz QPO frequency ratios in the neutron star sources. While the distribution of ratios inferred from an occurrence of a single QPO seems to be consistent with a random…
A kilohertz quasi-periodic oscillation (kHz QPO) is an observationally robust high-frequency timing feature detected from neutron star low-mass X-ray binaries (LMXBs). This feature can be very useful to probe the superdense core matter of…
We report the discovery of twin kHz quasi-periodic oscillations (QPOs) in the persistent X-ray flux of the new X-ray transient XTE J2123-058. We detected the QPOs in data taken with the proportional counter array on board the Rossi X-ray…
We report on a comprehensive analysis of the kilo-Hz (>~600 Hz) quasi-periodic oscillations (kHz QPOs) detected from the neutron star X-ray transient Aquila X-1 (Aql X-1) with the Rossi X-ray Timing Explorer, between 1997 and 2007. Among…
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 lines in a frequency vs. X-ray count rate diagram. We find…
In observations with the Rossi X-ray Timing Explorer we have discovered quasi-periodic oscillations (QPOs) near 1 kHz from 4U 1705-44, a low--mass X-ray binary with a neutron star classified as an atoll source. In six separate observations,…
We discovered kHz QPOs in 80 archived RXTE observations from the peculiar low-mass X-ray binary (LMXB) Circinus X-1. In 11 cases these appear in pairs in the frequency range of ~230 Hz to ~500 Hz for the upper kHz QPO and ~56 Hz to ~225 Hz…
We report the discovery with the RXTE/PCA of twin kHz QPOs in Cir X-1. Eleven cases of simultaneous double QPOs occurred, with significances of up to 6.3 and 5.5 sigma and centroid frequencies ranging between approximately 56-225 and…
Based on the interpretation of the twin kilohertz Quasi Periodic Oscillations (kHz QPOs) of X-ray spectra of Low Mass X-Ray Binaries (LMXBs) to the Keplerian and the periastron precession frequencies at the magnetosphere-disk of X-ray…
The origin of quasi periodic modulations of flux in the kilohertz range (kHz QPOs), observed in low-mass X-ray binaries, is usually assumed to be physically distinct from that of the ``normal branch oscillations'' (NBOs) in the Z-sources.…
We have studied the rapid X-ray time variability in 99 pointed observations with the Rossi X-ray Timing Explorer (RXTE)'s Proportional Counter Array of the low-mass X-ray binary 1E~1724--3045 which includes, for the first time, observations…