The Island state of the Atoll Source 4U 1820--30

Abstract

We study the rapid X-ray time variability in all public data available from the \textit{Rossi X-ray Timing Explorer's} Proportional Counter Array on the atoll source 4U 1820--30 in the low-luminosity island state. A total of $\sim 46$ ks of data were used. We compare the frequencies of the variability components of 4U 1820--30 with those in other atolls sources. These frequencies were previously found to follow a universal scheme of correlations. We find that 4U 1820--30 shows correlations that are shifted by factors of $1.13\pm 0.01$ and $1.21\pm 0.02$ with respect to those in other atoll sources. These shifts are similar to, but smaller than the shift factor $\sim 1.45$ previously reported for some accreting millisecond pulsars. Therefore, 4U 1820--30 is the first atoll source which shows no significant pulsations but has a significant shift in the frequency correlations compared with other 3 non-pulsating atoll sources.

arXiv comment21 pages, 8 Figures, submitted to ApJ

References in corpus (21)

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• A Unified Description of the Timing Features of Accreting X-ray Binaries
• Sonic-Point Model of Kilohertz Quasi-Periodic Brightness Oscillations in Low-Mass X-ray Binaries
• Photospheric radius expansion X-ray bursts as standard candles
• The broad-band power spectra of X-ray binaries
• A Remarkable Three Hour Thermonuclear Burst From 4U 1820-30
• Non-linear resonance in nearly geodesic motion in low-mass X-ray binaries
• Discovery of a Second Millisecond Accreting Pulsar: XTE J1751-305
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• Optical spectra of the carbon-oxygen accretion discs in the ultra-compact X-ray binaries 4U 0614+09, 4U 1543-624 and 2S 0918-549
• New class of low frequency QPOs: signature of nuclear burning or accretion disk instabilities?
• Relations Between Timing Features and Colors in Accreting Millisecond Pulsars
• Radio detections of the neutron star X-ray binaries 4U 1820-30 and Ser X-1 in soft X-ray states
• Low and high frequency variability as a function of spectral properties in the bright X-ray binary GX 5-1
• A Closer Look at the Soft X-ray Transient X1608-52: Long-term Optical/X-ray Observations
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• An accreting millisecond pulsar with black hole-like X-ray variability: IGR J00291+5934
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• The aperiodic X-ray variability of the accreting millisecond pulsar SAX J1808.4-3658
• Rapid X-ray variability properties during the unusual very hard state in neutron-star low-mass X-ray binaries
• Discovery of kilohertz quasi-periodic oscillations and state transitions in the low-mass X-ray binary 1E~1724-3045 (Terzan 2)
• A Comprehensive Study of Thermonuclear X-ray Bursts from 4U 1820-30 with NICER: Accretion Disk Interactions and a Candidate Burst Oscillation
• Discovery of a correlation between the frequency of the mHz quasi-periodic oscillations and the neutron-star temperature in the low-mass X-ray binary 4U 1636-53
• High-frequency variability in neutron-star low-mass X-ray binaries
• On the geometric nature of low-frequency quasi-periodic oscillations in neutron-star low-mass X-ray binaries
• The stochastic X-ray variability of the accreting millisecond pulsar MAXI J0911-655
• Broad iron emission line and kilohertz quasi-periodic oscillations in the neutron star system 4U 1636-53
• On the frequency correlations of low-frequency QPOs with kilohertz QPOs in accreting millisecond X-ray pulsars
• Spectral state transitions in Circinus ULX5
• Drifts of the marginally stable burning frequency in the X-ray binaries 4U 1608--52 and Aql X--1
• A new correlation with lower kilohertz quasi-periodic oscillation frequency in the ensemble of low-mass X-ray binaries
• Discovery of twin kHz quasi periodic oscillations in the low mass X-ray binary XTE J1701-407
• New Transient ULX Candidate in NGC 4254: Evidence of Circumbinary Disk?