Spin-up/spin-down of neutron star in Be-X-ray binary system GX 304-1

Постнов, К. А.; Mironov, Aleksej; Lutovinov, A.; Шакура, Н. И.; Kochetkova, A.; Tsygankov, Sergey S.

doi:10.1093/mnras/stu2155

Cited by 36 publications

(43 citation statements)

References 43 publications

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“…1). To our knowledge, this "triple-peaked" outburst behavior had not been seen in any other source, although some sources, such as A 0535+262 (see, e.g., Caballero et al 2013, and references therein) or GX 304−1 (Nakajima et al 2012;Postnov et al 2015b), feature rare "doublepeaked" outbursts. What causes the source to undergo outbursts Article number, page 1 of 13 arXiv:1708.04473v1 [astro-ph.HE] 15 Aug 2017 A&A proofs: manuscript no.…”

Section: Introductionmentioning

confidence: 62%

“…This is in very good agreement with the expected value for the hardness ratio in case of a filled accretion column, whereas a hardness in the range of 10-16 is expected for a hollow accretion column (see Figs. 6 and 7 of Postnov et al 2015b). Furthermore, the derived hardness saturates above a (one-column) accretion rate of 1 × 10 17 g s −1 , while the evolution of the hardness shown in Fig.…”

Section: Accretion Regimes In Gro J1008−57mentioning

confidence: 74%

“…Furthermore, the derived hardness saturates above a (one-column) accretion rate of 1 × 10 17 g s −1 , while the evolution of the hardness shown in Fig. 6 of Postnov et al (2015b) suggests a saturation above 5-7×10 17 g s −1 . This value scales with the height of the filled accretion column, which itself anti-correlates with the magnetic field strength at a given mass accretion rate (K. Postnov, priv.…”

Section: Accretion Regimes In Gro J1008−57mentioning

confidence: 84%

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Evidence for different accretion regimes in GRO J1008−57

Kühnel

Fürst

Pottschmidt

et al. 2017

A&A

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We present a comprehensive spectral analysis of the BeXRB GRO J1008−57 over a luminosity range of three orders of magnitude using NuSTAR , Suzaku and RXTE data. We find significant evolution of the spectral parameters with luminosity. In particular the photon index hardens with increasing luminosity at intermediate luminosities between 10 36 -10 37 erg s −1 . This evolution is stable and repeatedly observed over different outbursts. However, at the extreme ends of the observed luminosity range, we find that the correlation breaks down, with a significance level of at least 3.7σ. We conclude that these changes indicate transitions to different accretion regimes, which are characterized by different deceleration processes, such as Coulomb or radiation breaking. We compare our observed luminosity levels of these transitions to theoretical predications and discuss the variation of those theoretical luminosity values with fundamental neutron star parameters. Finally, we present detailed spectroscopy of the unique "triple peaked" outburst in 2014/15 which does not fit in the general parameter evolution with luminosity. The pulse profile on the other hand is consistent with what is expected at this luminosity level, arguing against a change in accretion geometry. In summary, GRO J1008−57 is an ideal target to study different accretion regimes due to the well constrained evolution of its broad-band spectral continuum over several orders of magnitude in luminosity.

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Section: Introductionmentioning

confidence: 62%

Section: Accretion Regimes In Gro J1008−57mentioning

confidence: 74%

Section: Accretion Regimes In Gro J1008−57mentioning

confidence: 84%

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Evidence for different accretion regimes in GRO J1008−57

Kühnel

Fürst

Pottschmidt

et al. 2017

A&A

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“…Observations with the Fermi/GBM instruments showed, that a strong outburst activity of the source is accompanied by significant changes in the source pulse period. The latter can be explained in the frame of the quasi-spherical settling accretion onto the neutron star (Postnov et al, 2015). 2RXP J130159.6-635806 is a faint X-ray source, discovered by the ROSAT observatory during all sky survey (sometimes this source is named IGR 13020-6359 as well, due to its first detection in hard X-ray with INTEGRAL).…”

Section: Discussionmentioning

confidence: 99%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

234

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High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

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“…The value of Π su is independent of the system and is in the range of ∼4.6 to 10 (Shakura et al 2012;Postnov et al 2015). In the present case, Π su was ] for the luminosity of 10 38 erg s −1 was estimated to beṀ 16 =100 during Suzaku observations.…”

Section: Spin-period and Magnetic Field Of The Pulsarmentioning

confidence: 55%

Broad-band spectroscopy of the transient X-ray binary pulsar KS 1947+300 during 2013 giant outburst: Detection of pulsating soft X-ray excess component

Epili

Naik

Jaisawal

2016

Res. Astron. Astrophys.

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We present the results obtained from detailed timing and spectral studies of the Be/X-ray binary pulsar KS 1947+300 during its 2013 giant outburst. We used data from Suzaku observations of the pulsar at two epochs i.e. on 2013 October 22 (close to the peak of the outburst) and 2013 November 22. X-ray pulsations at ∼18.81 s were clearly detected in the light curves obtained from both observations. Pulse periods estimated during the outburst showed that the pulsar was spinning up. The pulse profile was found to be single-peaked up to ∼10 keV beyond which a sharp peak followed by a dip-like feature appeared at hard X-rays. The dip-like feature has been observed up to ∼70 keV. The 1-110 keV broad-band spectroscopy of both observations revealed that the best-fit model comprised of a partially absorbed Negative and Positive power law with EXponential cutoff (NPEX) continuum model along with a blackbody component for the soft X-ray excess and two Gaussian functions at 6.4 and 6.7 keV for emission lines. Both the lines were identified as emission from neutral and He-like iron atom. To fit the spectra, we included the previously reported cyclotron absorption line at 12.2 keV. From the spin-up rate, the magnetic field of the pulsar was estimated to be ∼1.2×1012 G and found to be comparable to that obtained from the detection of the cyclotron absorption feature. Pulse-phase resolved spectroscopy revealed the pulsating nature of the soft X-ray excess component in phase with the continuum flux. This confirms that the accretion column and/or accretion stream are the most probable regions of pulsar's soft X-ray excess emission. The presence of the pulsating soft X-ray excess in phase with continuum emission may be the possible reason for not observing the dip at soft X-rays.

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Spin-up/spin-down of neutron star in Be-X-ray binary system GX 304-1

Cited by 36 publications

References 43 publications

Evidence for different accretion regimes in GRO J1008−57

Evidence for different accretion regimes in GRO J1008−57

High-mass X-ray binaries in the Milky Way

Broad-band spectroscopy of the transient X-ray binary pulsar KS 1947+300 during 2013 giant outburst: Detection of pulsating soft X-ray excess component

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