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2003-11

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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/99391

Evidence of a decrease of kHz quasi-periodic oscillation peak separation towards low frequencies in 4U 1728-34 (GX 354-0)

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http://dx.doi.org/10.1046/j.1365-8711.2003.07186.x

Abstract

We have produced the colour-colour diagram of all the observations of 4U 1728-34 available in the Rossi X-ray Timing Explorer public archive (from 1996 to 2002) and found observations filling in a previously reported `gap' between the island and the banana X-ray states. We have made timing analysis of these gap observations and found, in one observation, two simultaneous kHz quasi-periodic oscillations (QPOs). The timing parameters of these kHz QPOs fit in the overall trend of the source. The `lower' kHz QPO has a centroid frequency of ~308 Hz. This is the lowest `lower' kHz QPO frequency ever observed in 4U 1728-34. The peak frequency separation between the `upper' and the `lower' kHz QPO is Δν= 274 +/- 11 Hz, significantly smaller than the constant value of Δν~ 350 Hz found when the `lower' kHz QPO frequency is between ~500 and 800 Hz. This is the first indication in this source for a significant decrease of kHz QPO peak separation towards low frequencies. We compare the result briefly to theoretical models for kHz QPO production.

Subject

Estels de neutrons, Estels, Astronomia de raigs X

Subject (English)

Neutron stars, Stars, X-ray astronomy

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Articles publicats en revistes (Física Quàntica i Astrofísica)

Citation

MIGLIARI, Simone, VAN DER KLIS, M. and FENDER, R. P. Evidence of a decrease of kHz quasi-periodic oscillation peak separation towards low frequencies in 4U 1728-34 (GX 354-0). Monthly Notices of the Royal Astronomical Society. 2003. Vol. 345, num. 3, pags. L35-L39. ISSN 0035-8711. [consulted: 9 of August of 2026]. Available at: https://hdl.handle.net/2445/99391

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