INTEGRAL observation of the accreting pulsar GX 1+4
Ferrigno, C., Segreto, A., Santangelo, A., Wilms, J. (Joern), Kreykenbohm, I., Denis, M. and Staubert, R.. (2007) INTEGRAL observation of the accreting pulsar GX 1+4. Astronomy & Astrophysics, Vol.462 (No.3). 995-U71. ISSN 0004-6361Full text not available from this repository.
Official URL: http://dx.doi.org/10.1051/0004-6361:20053878
Aims: We present the results of the INTEGRAL monitoring campaign on the accreting low mass X-ray binary pulsar GX1+4 performed during the Galactic plane scan of the INTEGRAL Core Programme. Methods. The source was observed in different luminosity states ranging from L20-40 keV = 1.7 x 10(-10) erg cm(-2) s(-1), to L20-40 keV = 10.5 x 10(-10) erg cm(-2) s(-1) for about 779 ks from March 2003 until October 2004. Results. Our observations confirm the secular spin down of GX 1+4 with the spin period (P-s) varying from 139.63 s to 141.56 s. In the highest luminosity state, a spin-up phase is observed. The phase-averaged spectrum of the source was modelled either with an absorbed cut-off power law or with a Comptonization model with significantly different parameters in the two brightest luminosity states. No evidence of any absorption-like feature is observed in the phase averaged spectrum up to 110 keV. At highest luminosity, the source is found to pulsate up to 130 keV. Phase resolved spectroscopy reveals a phase-dependent continuum and marginal evidence for an absorption feature at 34 +/- 2 keV in the descending part of the pulse. If interpreted as due to electron resonant cyclotron scattering, the magnetic field in the emitting region would be (2.9 +/- 0.2) x 10(12) (1+z) G where z is the gravitational red shift of the emitting region. We also observed a very low luminosity state, typical of this source, which lasted for about two days during which the source spectrum was modelled by a simple power law, and a pulsed signal was still detectable in the 15-100 keV energy range.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Divisions:||Faculty of Science > Physics|
|Journal or Publication Title:||Astronomy & Astrophysics|
|Number of Pages:||14|
|Access rights to Published version:||Restricted or Subscription Access|
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