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  4. Kilohertz quasi-periodic oscillation and atoll source states in 4U 0614+09
 
research article

Kilohertz quasi-periodic oscillation and atoll source states in 4U 0614+09

vanderKlis, M.
•
vanParadijs, J.
•
Lewin, W.H.G.
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1997
The Astrophysical Journal

We report three RXTE/PCA observations of the low-mass X-ray binary 4U 0614+09. They show strong (similar to 30% rms) band-limited noise with a cutoff frequency varying between 0.7 and 15 Hz in correlation with the X-ray flux, f(x). We observe two nonsimultaneous 11%-15% (rms) kHz peaks near 728 and 629 Hz in the power spectra of two of our observations when f(x) similar to 10(-9) ergs cm(-2) s(-1) (2-10 keV) but find no quasi-periodic oscillations (QPOs; <6% rms) when f(x) is half that. We suggest that count rate may not be a good measure for II;P even in sources as intrinsically weak as 4U 0614+09 and that QPO frequency and noise cutoff frequency track M over dot more closely than count rate. The QPO increases in rms amplitude from 11% +/- 1.3% at 3 keV to 37% +/- 12% at 23 keV; the fractional amplitude of the band-limited noise is energy independent. This suggests different sites of origin for these two phenomena. The spectrum of the oscillating flux roughly corresponds to a black body with temperature 1.56 +/- 0.2 keV and radius 500 +/- 200 m (other models fit as well), which might indicate that the oscillations originate at a small region on the neutron star surface.

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Type
research article
DOI
10.1086/310803
Web of Science ID

WOS:A1997XR07900010

Author(s)
vanderKlis, M.
vanParadijs, J.
Lewin, W.H.G.
Lamb, F.K.
Vaughan, B.A.
Kuulkers, E.
Psaltis, D.  
Mendez, M.
Date Issued

1997

Published in
The Astrophysical Journal
Volume

485

Start page

L37

End page

L40

Subjects

accretion, accretion disks

•

stars, individual (4U 0614+091)

•

stars, neutron

•

X-rays, stars

•

Power Spectra

•

Ray

Editorial or Peer reviewed

REVIEWED

Written at

OTHER

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Available on Infoscience
November 25, 2010
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/58879
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