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Title: Flares, broadening of the pulse-frequency peak and quasi-periodic oscillations in the transient X-ray pulsar 4U 1901+03
Authors: James, Marykutty
Paul, Biswajit
Devasia, Jincy
Indulekha, Kavila
Keywords: individual: 4U 1901+03
stars: neutron
pulsars: individual
4U 1901+03
X-rays binaries
X-rays stars
Issue Date: Jan-2011
Publisher: Wiley-Blackwell for the RAS
Citation: Monthly Notices of the Royal Astronomical Society, 2010, Vol.410, p1489
Abstract: After a long quiescence of three decades, the transient X-ray pulsar 4U 1901+03 became highly active in 2003 February. From the analysis of a large number of Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) observations of this source, we report here the detection of X-ray flares, a broadening of the pulse-frequency feature and quasi-periodic oscillations (QPOs). The X-ray flares showed spectral changes, had a duration of 100-300 s, and were more frequent and stronger during the peak of the outburst. In most of the observations during the outburst we also detected a broadening of the pulse-frequency peak. We have also found intensity-dependent changes in the pulse profile at very short time-scales. This reveals a coupling between the periodic and the low-frequency aperiodic variabilities. In addition, near the end of the outburst we have detected a strong QPO feature centred at ˜0.135 Hz. The QPO feature is broad with a quality factor of 3.3 and with an rms value of 18.5 ± 3.1 per cent. Using the QPO frequency and the X-ray luminosity during the QPO detection period we estimated the magnetic field strength of the neutron star as 0.31 × 1012 G which is consistent with the value inferred earlier under the assumption of spin equilibrium.
Description: Restricted Access. An open-access version is available at (one of the alternative locations)
ISSN: 0035-8711
1365-2966 (Online)
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Copyright: 2010 The authors & the Royal Astronomical Society
Appears in Collections:Research Papers (A&A)

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