<i>INTEGRAL</i> observations of the variability of OAO 1657-415

Barnstedt, J.; Staubert, R.; Santangelo, A.; Ferrigno, C.; Horns, D.; Klochkov, D.; Kretschmar, P.; Kreykenbohm, I.; Segreto, A.; Wilms, J.

doi:10.1051/0004-6361:20078707

Cited by 34 publications

(61 citation statements)

References 37 publications

(82 reference statements)

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“…The pulse fraction increase with the energy was also found for several other X-ray pulsars (see, e.g. [7,8]). Using INTEGRAL data, Tsygankov & Lutovinov [9] studied in detail the pulse fraction dependence on the energy and luminosity for ten bright X-ray pulsars in hard X-rays.…”

Section: Introductionsupporting

confidence: 74%

X-ray pulsars through the eyes of INTEGRAL

Lutovinov

Tsygankov

2008

AIP Conference Proceedings

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Abstract.Recent results of the spectral and timing analysis of X-ray pulsars in hard X-rays with the INTEGRAL observatory are reviewed. The evolution of the cyclotron line energy with the source luminosity was studied in detail for the first time for several sources. It was shown that for V0332+53 this dependence is linear, but for 4U0115+63 and A0535+262 it is more complicated. There are some evidences of the "reverse" evolution for GX301-2 and Her X-1, and no evolution was found for Vela X-1, Cen X-3, etc. A strong dependence of the pulse fraction on the energy and source luminosity was revealed and studied in detail. A prominent feature in the pulse fraction dependence on the energy was discovered near the cyclotron frequency for several bright sources. The obtained results are compared with results of observations in standard X-rays and briefly discussed in terms of current models; some preliminary explanations are proposed.

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Section: Introductionsupporting

confidence: 74%

X-ray pulsars through the eyes of INTEGRAL

Lutovinov

Tsygankov

2008

AIP Conference Proceedings

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“…Despite the fairly long INTE-GRAL exposure time for this pulsar and the hard spectrum of this object, as yet no cyclotron absorption line has been reliably detected in its spectrum (Filippova et al 2005;Barnstedt et al 2008). This may be indicative of a fairly strong magnetic field near the neutron star surface, just as is observed with INTEGRAL in other pulsars (see, e.g., Lutovinov 2005a, 2005b).…”

Section: Resultsmentioning

confidence: 94%

Timing characteristics of the hard X-ray emission from bright X-ray pulsars based on INTEGRAL data

2009

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Abstract-We review the results of a timing analysis of the observations for ten bright X-ray pulsars (with fluxes >100 mCrab in the 20-100 keV energy band) that fell within the INTEGRAL field of view from 2003 to 2007. The dependence of the pulse profile on the energy and intrinsic source luminosity has been investigated; particular attention has been paid to searching for changes in the pulse profile near the cyclotron frequency. The dependence of the pulsed fraction for X-ray pulsars on their luminosity and energy band has been studied in detail for the first time.PACS numbers : 97.80. Ip; 97.60.Id; 95.75.Wx

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“…The timescale t ∞ between two torque reversals varies from source to source. Some pulsars show numerous torque reversals with moderate spin period derivative (e.g., Vela X−1, Her X−1; Bildsten et al 1997), others show quasi-periodic torque reversals superimposed on a longterm spin-up trend (e.g., OAO 1657−415, Barnstedt et al 2008; EXO 2030+375, Fermi/GBM 6 ; SAX J2103.5+4545, Camero et al 2014), while others show steady spin-up or spin-down sporadically interrupted by a torque reversal (e.g., GX 1+4, González-Galán et al 2012;4U 16264U −67, Beri et al 20144U 1907+09, Inam et al 2009. It is interesting to compare, for each pulsar, t ∞ with Δt gl , the time needed to reach the critical rotational lag for depinning.…”

Section: Observabilitymentioning

confidence: 99%

Properties and observability of glitches and anti-glitches in accreting pulsars

Ducci¹,

Pizzochero²,

Doroshenko³

et al. 2015

A&A

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Several glitches have been observed in young, isolated radio pulsars, while a clear detection in accretion-powered X-ray pulsars is still lacking. We use the Pizzochero snowplow model for pulsar glitches as well as starquake models to determine for the first time the expected properties of glitches in accreting pulsars and their observability. Since some accreting pulsars show accretion-induced long-term spin-up, we also investigate the possibility that anti-glitches occur in these stars. We find that glitches caused by quakes in a slow accreting neutron star are very rare and their detection extremely unlikely. On the contrary, glitches and anti-glitches caused by a transfer of angular momentum between the superfluid neutron vortices and the non-superfluid component may take place in accreting pulsars more often. We calculate the maximum jump in angular velocity of an anti-glitch and we find that it is expected to be ΔΩ a−gl ≈ 10 −5 −10 −4 rad s −1 . We also note that since accreting pulsars usually have rotational angular velocities lower than those of isolated glitching pulsars, both glitches and anti-glitches are expected to have long rise and recovery timescales compared to isolated glitching pulsars, with glitches and anti-glitches appearing as a simple step in angular velocity. Among accreting pulsars, we find that GX 1+4 is the best candidate for the detection of glitches with currently operating X-ray instruments and future missions such as the proposed Large Observatory for X-ray Timing (LOFT).

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INTEGRAL observations of the variability of OAO 1657-415

Cited by 34 publications

References 37 publications

X-ray pulsars through the eyes of INTEGRAL

X-ray pulsars through the eyes of INTEGRAL

Timing characteristics of the hard X-ray emission from bright X-ray pulsars based on INTEGRAL data

Properties and observability of glitches and anti-glitches in accreting pulsars

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